Dissertation Final PDF

Effects of Chronic Zinc Magnesium Aspartate
(ZMA) Supplementation on Strength & Acute
Recovery In Recreational Male Resistance
Athletes
by
Arsalan Javaid
13843290

A dissertation
submitted in partial fulfillment of the requirements for the
degree of:
BACHELOR OF SCIENCE (HONOURS) SPORT AND EXERCISE
SCIENCE (WITH NUTRITION)
2016

Abstract
Background: Resistance or Strength training is a modality of exercise with anabolic foundations
and implications (Fleck and Kraemer, 2014). Athletes are constantly striving to break plateaus and
optimise performances using nutritional interventions and ergogenic aids. Doping and the use of
anabolic steroids is a trend amongst competitive bodybuilders and power lifters (Haff and Travis,
2015), although there are competitors who seek ergogenic aids through natural and legal means.
ZMA is a supplement marketed as having anabolic properties, primarily, boosting testosterone and
recovery combining the synergistic effects of Zinc Monomethionine Aspartate, Magnesium Aspartate
and Vitamin B6 (Villepigue and Rivera, 2012).
Aims: To investigate the effects of 4 weeks of ZMA supplementation on 1RM strength and acute
recovery in recreational resistance athletes,
Methods: 14 healthy recreational resistance athletes (mean ± SD), age 22.9 ± 2.9 years, height 180
± 4.7 cm and body mass 83.6 kg ± 9.4 kg , participated in a study approved by the University of
Brighton’s Ethics committee. Participants completed familiarisation protocols prior to preliminary
testing using a Concept2 Dyno Dynamometer to perform the following exercises: chest press,
diverging row, and leg press. 14 participants were randomly assigned to one of two conditions:
ZMA (n = 7) or Placebo (n = 7). Participants performed 3 reps at a minimal-maximal exertion effort:
25% (minimal), 50% (medial) 100% (maximal – 1RM). There was a static-recovery period of 5
minutes in between exercises. Data analysis consisted of a separated two-way mixed design ANOVA
[2x3; Time (pre vs. post) x Condition (placebo vs. ZMA)] to determine significant changes between
conditions (P<0.05).
Results: A significant interaction effect was not found between time (pre & post) and supplement
(PL & ZMA) in strength on the chest press with ZMA: F (1, 12) = 1.96, P = 0.187 and diverging row: F
(1,12) = 0.02, P = 0.884; A significant interaction effect was found for 1RM strength on the leg pr ess:

F (1,12) = 1.96, P = 0.000. Average hours slept (HS) for the ZMA group increased by 5.8%, average
awakenings decreased by -31.3%, and Quality of Sleep (QoS) increased by 22.1%.
Conclusions: It remains equivocal as to whether ZMA supplementation has anabolic properties as
the findings of this study would suggest otherwise. An improvement in solely 1RM leg press
strength is not sufficient and there are no clear explanations as to why no changes were observed
in the chest press or diverging row. The increases in recovery values are open to interpretation and
further research, although it would be suggested that these improvements are a synergistic effect of
Magnesium (Mn). Further research is required analysing a broader range of variables and possibly
comparing the effects of the synergist components of ZMA against the supplement as a complete
formula.
Keywords: Zinc, Magnesium, Vitamin B6, Resistance, Training, Strength, Recovery,
Hypertrophy, Testosterone
I

Acknowledgements
I would first and foremost like to thank Dr Alan Richardson for
giving me the opportunity to enter this course. A huge thank
you to my dissertation supervisor Dr Gary Brickley for giving me
guidance as well as patience during the completion of my
dissertation, and a further thank you and appreciation to all the
other staff at The University of Brighton who guided me along
the way. Thank you and eternal gratitude to Rabia Alam, who
gave me the encouragement to persist and the belief to reach
the stage that I am at. Furthermore, I would like to thank my
supportive family, my personal and university friends (Oliver
Wise, Zarthast Bajwa, Marcel Illés & Shuaib Dalvi) for their
continual and moral support. Last but not least, my grandfather
who is no longer with me but gives me strength spiritually and
faithfully. My weakness is sometimes my self belief, but the
patience that you show gives me new found strengths and
eliminates all of my weaknesses and doubts, every time. Thank
you all, once again. ‫ا‬‫ل‬‫ح‬َ‫دْم‬ ‫هلل‬ .

TABLE OF CONTENTS
ABSTRACT ......................................................................................................................I
ACKNOWLEDGEMENTS ..............................................................................................II
TABLE OF CONTENTS ................................................................................................III
LIST OF TABLES ............................................................................................................ VI
LIST OF FIGURES ...................................................................................................... VII
LIST OF ABBREVIATIONS ....................................................................................... VIII
Chapter
I INTRODUCTION ............................................................................................ 1
1.1 Purpose and significance of the study................................................... 2
Chapter
II LITERATURE REVIEW .................................................................................... 3
2.1 The Physical Nature And Demands of Resistance Training .......... 3
II

2.1.1 The Correlation Between Muscle CSA and Strength......... 9
2.1.2 Effects of Resistance Training on Recovery....................... 13
2.2 The Endocrine System ...................................................................... 15
2.2.1 Hormonal Response to Resistance Training...................... 16
2.3 Limitations Of Strength & Recovery– Peripheral Factors....... 17
2.3.1 Physiological Response To Specific Exercise
Movements Intensity & Duration........................................................................ 17
2.3.2 Recovery & Restoration....................................................... 20
2.4 Ergogenic Aids – Nutritional Intervention Strategies.................... 21
2.4.1 Zinc Aspartate........................................................................ 22
2.4.2 Magnesium Aspartate.......................................................... 22
2.4.3 Vitamin B6.............................................................................. 22
2.4.4 Role Of ZMA & Effect on Strength & Recovery............ 23
2.5 Dosage, Administration & Timing...................................................... 26
2.5 Dosage, Administration & Timing................................................... 26
2.5.1 Dosage & Safety For Human Consumption..................... 27
2.5.2 Timing...................................................................................... 27
2.5.3 Performance Measures & Test Reliability........................ 29
2.6 Summary of Literature....................................................................... 30
2.7 Specific Research Aims...................................................................... 31
2.8 Research Hypothesis.......................................................................... 32
2.9 Assumptions ........................................................................................ 32
2.10 Delimitations...................................................................................... 33
2.11 Limitations.......................................................................................... 34
Chapter
III METHODS ..................................................................................................... 34
3.1 Experimental Approach To The Problem ..................................... 34
3.2 Participants ......................................................................................... 36
3.3 Experimental Procedure...................................................................... 38
III

3.3.1 3-Day Sleep Diary................................................................... 38
3.4 Supplementation............................................................................... 39
3.5 Statistical Analysis................................................................................ 39
Chapter
IV RESULTS ........................................................................................................39
4.1 1RM Performance ................................................................................40
4.2 Recovery.................................................................................................42
Chapter
V DISCUSSION .................................................................................................43
5.1 Summary of Findings .....................................................................44
5.2 Differences In Hormonal Response...............................................45
5.3 Mechanisms of Hypertrophy ........................................................46
5.4 Critical Analysis................................................................................48
5.5 Limitations........................................................................................50
Chapter
VI CONCLUSION ...........................................................................................50
APPENDICES..................................................................................................................52
APPENDIX A- Participation Information Sheet .....................................52
APPENDIX B- Informed Consent Form...................................................57
APPENDIX C- Medical Questionnaire.....................................................58
APPENDIX D- Sessional Medical Form...................................................59
APPENDIX E- Risk Assessment Form......................................................60
APPENDIX F- COSSH Form.......................................................................62
APPENDIX G- Sleep Diary.........................................................................70
APPENDIX E- Pilot Testing........................................................................71
REFERENCES..................................................................................................................73
IV

LIST OF TABLES
Table 1 Summary of Long-Term Studies Evaluating the Effects
of Training Intensity on Muscle Hypertrophy (Schoenfeld, 2013)
PAGE
3
28
28
40
V

Table 2 Descriptive statistics (mean ± SD) for the seated bench
press, seated bench pull, and seated leg press from the 3 trials
for both the whole sample and the subsample.*†
(Bampouras et al., 2014)
Table 3 Reliability and sensitivity statistics for all exercises between trials,
for both the whole sample and the subsample.*‡
Table 4 Changes in strength pre & post supplementation.
Compared means are represented as SD

LIST OF FIGURES
Figure 1 Significance in both HL & LL groups for muscle thickness
increase in the elbow flexors from baseline to post via ultrasound
imaging (HL=5.3 vs. LL=8.6%,) (p < 0.01) (Schoenfeld et al., 2015)
Figure 1.1 Significance in both HL & LL groups for muscle thickness
increase in the elbow extensors from baseline to post via ultrasound
imaging (HL=6.0% vs. LL=5.2%,) (p <0.05). (Schoenfeld et al., 2015)
Figure 1.2 Significance in both HL & LL groups for muscle thickness
increase in the quadriceps femoris from baseline to post via ultrasound
imaging (HL=9.3% vs. LL=9.5%,) (p <0.05) (Schoenfeld et al., 2015)
Figure 1.3 Significant difference in 1RM back squat from baseline to
post (HL=19.6%=sig. vs. LL=8.8%=non-sig.) (Schoenfeld et al., 2015)
Figure 1.4 Significant different in 1RM bench press from baseline to
post (HL=6.5%=sig. vs. LL=2.0%=non-sig. )(Schoenfeld et al., 2015)
Figure 1.5 Significant difference in muscular endurance from baseline
to post (HL=0%=non-sig. vs. LL=2.0%=16.6%=sig.). (Schoenfeld et al.,
2015)
PAGE
10
11
11
12
12
13
19
21
VI

Figure 2 Diagram showing major divisions of the nervous system
(Plowman and Smith, 2011)
Figure 3 Mean GH concentrations at each time point between SLEEP and
SLD sessions during exercise and recovery. (Ritsche, Nindl and Wideman,
2014)
Figure 4 Schematic of Experimental Procedure from Baseline to Post
Figure 5 Schematic of Exercise & Testing protocol
Figure 6 Mean percentage change (%) pre and post supplementation on
1RM strength. SD (±) represented by error bars.
Figure 7 Mean percentage change (%) pre and post supplementation on
sleep (average hours slept, average awakenings, average quality of sleep)
across 3 days. SD (±) represented by error bars.
Definition of Abbreviations (Terms)
LIST OF ABBREVIATIONS
1RM 1 Repetition Maximum
CM Centimeters
CNS Central Nervous System
CSA Cross Sectional Area
CT Computerised Tomography
DHEA Dehydroepiandrosterone
VII

EIGR Exercise-induced Growth Hormone Response
EMG Electromyography
FAD Filament Area Density
GH Growth Hormone
HG Hand Grip
HGH Human Growth Hormone
HL High Load
HMB Beta-Hydroxy Beta-Methylbutyric Acid
HR Heart Rate
kg Kilograms
LL Low Load
Mcg Microgram
Mg Milligram
MFP Muscular Force Production
MIT Minimum Intensity Threshold
Mn Magnesium
MP Mean Power
MRI Magnetic Resonance Imaging
PP Peak Power
RPE Rate of Perceived Exertion
SLD Sleep Deprivation
V O2 max Maximal Oxygen Uptake
Zn Zi
VIII

1
1.0 Introduction
1.1 Purpose and significance of the study
ZMA (Zinc Monomethionine Aspartate, Magnesium Aspartate and Vitamin
B6) is a synergistic supplement, which is said to possess ergogenic benefits
such as increasing anabolic hormone levels, improving recovery time and
increasing strength and muscle (Brilla and Conte, 2000). Zinc (Zn) &
Magnesium (Mg) are said to increase levels of Insulin-like Growth Factor-I
(IGF-I). Zn, as a single chemical element, could contribute towards the
elevation of serum testosterone (Maggio et al., 2014; Shafiei et al., 2011).
The increase in IGF-I and testosterone would mean an improvement in
muscle function and physical performance as both hormones have
anabolic properties (Maggio et al., 2011). Vitamin B-6 completes the
formulation of the ZMA supplement. It is needed to aid the body’s
metabolism; it is especially essential in protein metabolism and the
production of more proteins such as hormones, neurotransmitters and
enzymes (Manore, 2000; Stover and Field, 2015). Early research has
suggested that exercises decreases Mn & Zn, thus, resulting in
testosterone and strength reductions, emphasising the role ZMA is
suggested to play (Greenwood et al., 2015)

2
Strength in sport and exercise is defined as the ability to produce force to
overcome the most resistance in a single effort; strength is used in short
periods and is one of the key foundations in resistance-based training and
also contributes to muscular endurance and power (Brown, 2001; McArdle
et al., 2001). Strength is vastly important within sport & exercise as it can
make a huge difference in athletic performance; the greater the level to
overcome or resist in a sport or physical activity demands a greater
requirement of strength (Joyce and Lewingdon, 2014). Beattie et al. (2014)
investigated the effect of strength training on performance in trained
endurance athletes using 26 previously published journals that fit a specific
criteria (athletes had to be trained endurance athletes with ≥6 months
endurance training, training ≥6 h per week OR V˙O2max≥50 mL/min/kg,
the strength interventions had to be ≥5 weeks in duration, and control
groups used); suggesting that the inclusion of strength training within an
endurance athletes training protocol would improve economy, muscle
power and performance (Beattie et al., 2014).
Kellmann & Kallus, (2001) define recovery as an inter- and intra-individual
multilevel (e.g. psychological, physiological, social) process over time for
the re-establishment of performance abilities (Kellmann & Kallus, 2001).
Recovery is a very important aspect of any sport or exercise modality in

3
order to achieve maximal results from performance (Beckmann and Elbe,
2015). As well as possessing anabolic properties, it is suggested that ZMA
improves recovery. However, there is clear equivocality on the recovery
properties of the supplement, as there appears to be limited or non-
existing evidence to support this claim.
The demand for ergogenic supplements is at a constant increase, as
athletes and the general population are using these as a means to improve
athletic performance, particularly in hypertrophy and recovery (Fink and
Mikesky, 2013). The International Society of Sports Nutrition has declared
ZMA’s anabolic effect as unknown, and the Australian Institute of Sport,
which advises athletes about ergogenic aids, has concluded that ZMA lacks
clear evidence of benefits (Burke, 2007; Wilborn et al., 2004). The aim of
the study was to investigate whether 28-days of chronic ZMA
supplementation would improve 1RM strength performance and acute
recovery in recreational male resistance-exercise athletes.
2.0 Literature Review

4
2.1 The Physical Nature and Demands of Resistance Training
Resistance training improves muscular strength and power, as well as
decreasing muscular fatigue and resulting in many other health and
physiological benefits (Ehrman et al., 2013). The intensity of resistance-
based exercise increases the activation of fast-twitch muscle fibers resulting
in a greater importance on mechanical stress (Sherwood, 2012; Trappe et
al., 2000). In order to fully stimulate muscle activation for programs that
target metabolic stress (Resistance exercise), a minimum intensity threshold
(MIT) is required (Ratamess et al. 2009).
Table 1 Summary of Long-Term Studies Evaluating the Effects of Training Intensity on
Muscle Hypertrophy (Schoenfeld, 2013)
Study Subjects Design Volume
Equated
?
Train
to
Failure
?
Measuremen
t
Findings
Campos
et al. (44)
32
untrained
young men
(5 served
as non-
Random
assignment to
either low
intensity (3-5
RM),
Yes Yes Muscle biopsy
Significant
increases
in CSA for
high-
intensity

5
exercising
controls)
intermediate
intensity (9-11
RM) for 3 sets
with 2 minute
rest intervals, or;
high intensity
(20-28 RM)
exercise.
Exercise
consisted of 2-4
sets of squat,
leg press and
leg extension,
performed 3
days a week for
8 weeks.
exercise;
no
significant
increase in
CSA for
low-
intensity
exercise
Leger et
al. (45)
24
untrained
middle-
aged men
Random
assignment to
either low
intensity (3-5
RM) or a high
intensity (20-28
RM) exercise.
Exercise
Yes Yes CT
No
differences
in CSA
between
low- and
high-
intensity
exercise

6
consisted of 2-4
sets of squat,
leg press and
leg extension,
performed 3
days a week for
8 weeks..
Lamon et
al. (46)
25
untrained
middle-
aged men
Random
assignment to
either low
intensity (3-5
RM) or a high
intensity (20-28
RM) exercise.
Exercise
consisted of 2-4
sets of squat,
leg press and
leg extension,
performed 3
days a week for
8 weeks.
Yes Yes CT
No
differences
in CSA
between
low- and
high-
intensity
exercise
Tanimoto
and Ishii
24
untrained
Random
assignment to
No Yes MRI

7
(40) young men either 50% RM
with a 6 second
tempo and no
relaxing phase
between
repetitions, 80%
RM with a 2
second tempo
and 1 second
relaxation
between
repetitions, or
50% RM with a
2 second tempo
and 1 second
relaxation
between
repetitions.
Exercise
consisted of 3
sets of knee
extensions,
performed 3
days a week for

8
12 weeks.
Tanimoto
et al. (47)
36
untrained
young men
(12 served
as non-
exercising
controls)
Random
assignment to
either 55-60%
RM with a 6
second tempo
and no relaxing
phase between
repetitions or
80-90% RM
with a 2 second
tempo and 1
second
relaxation
between
repetitions.
Exercise
consisted of 3
sets of squat,
chest press, lat
pulldown,
abdominal
bend, and back
extension,
No Yes
B-mode
ultrasound
No
differences
in CSA
between
low- and
high-
intensity
exercise

9
performed 2
days a week for
13 weeks.
Holm et
al. (48)
11untraine
d young
men
Random,
counterbalance
d performance
of 10 sets of
unilateral leg
extensions,
training one leg
at 70% 1RM
and the
contralateral leg
at 15.5% 1RM,
performed 3
days a week for
12 weeks.
Yes No MRI
Significantl
y greater
increases in
CSA in high
intensity
versus low
intensity
exercise
Mitchell
et al.
(50).
18
untrained
young men
Randomly
assignment to
perform 2 of 3
unilateral leg
extension
protocols: 3 sets
at 30% RM; 3 at
No Yes
MRI, muscle
biopsy
No
differences
in CSA
between
low- and
high-
intensity

10
80% RM; 1 set
at 80% RM.
Training was
carried out 3
days per week
for 10 weeks.
exercise
Schuenk
e et al.
(51)
34
untrained
young
women
Randomized
assignment to
either moderate
intensity (80-
85% RM) at a
tempo of 1-2
seconds, a low
intensity (~40-
60% RM) at a
tempo of 1-2
seconds, or
slow-speed
(~40-60% RM)
at a tempo of10
seconds
concentric and
4 seconds
eccentric.
No Yes Muscle biopsy
Significant
increases in
CSA for
high-
intensity
exercise; no
significant
increase in
CSA for
low-
intensity
exercise

11
Exercise
consisted of 3
sets of squat,
leg press, and
leg extension,
performed 2-3
days a week for
6 weeks
Ogasaw
ara et al.
(52)
9 untrained
young men
Non-
randomized
crossover
design to
perform 4 sets
of bench press
exercise at 75%
1RM. Training
was carried out
3 days a week
for 6 weeks.
After a 12
month washout
period, the
same protocol
was performed
No Yes MRI
No
differences
in CSA
between
low- and
high-
intensity
exercise

12
at 30% 1RM.
Schoenfeld (2013) collected and compared long-term studies that
evaluated the effects of training intensity on muscle hypertrophy (see table
1); intensities above 30% are needed for complete muscle fiber recruitment
during resistance training to achieve the MIT. The literature compared in
table 1 shows equivocality as to what, if any, hypertrophic effects are
discovered with low-intensity exercise in well-trained subjects, as
experimental studies on the topic in this population are insufficient
(Schoenfeld, 2013).
2.1.1 The Correlation Between Muscle CSA & Strength
There is a positive relationship between muscle CSA and strength (Baechle
and Earle, 2008). Recovery results in myofibrillar hypertrophy (leading to
an increase in muscle CSA) and strength gains increase when the muscles
grow and become stronger; these three factors are relative to one another
and are required to work in tandem for optimal results (Schoenfield, 2016).

13
Sarcoplasmic hypertrophy (which is very common amongst resistance
athletes) stimulates muscle growth but does not have an incremental effect
on muscular force production (MFP); the filament area density (FAD)
decreases and the CSA increases (Whipple and Eckhardt, 2012). When the
numbers of myosin and actin filaments/sarcomeres expand inside the cell
an increase in myofibrillar hypertrophy commences; resulting in greater
strength and size of the contractile unit of muscle, which subsequently
develops the ability to produce a greater force. Myofibrillar hypertrophy is
usually achieved by using heavier loads and lower repetitions and the
opposite for sarcoplasmic hypertrophy (Hoeger and Hoeger, 2016).
Jenkins et al. (2015) looked at how forearm flexion resistance exercises
differed amongst subjects individually (15 male subjects); comparing
electromyographic (EMG) amplitude, the number of repetitions completed,
and exercise volume during three sets to failure of high- (80% 1RM) versus
low-load (30% 1RM). The results of the study showed that the numbers of
repetitions completed were greater for the 30% 1RM group, while the
volume of exercise were similar in both 1RM groups (Jenkins et al., 2015).
Similarly, Schoenfeld (2015) studied the effects of Low Load (LL) Versus
High Load (HL) Resistance Training in 18 young trained males. The results
of the study found that both HL & LL conditions produced significant
increases in thickness of the elbow flexors (HL=5.3 vs. LL=8.6%,), elbow

14
extensors (HL=6.0 vs. LL=5.2%,), and quadriceps femoris (HL=9.3 vs.
LL=9.5%,) there were no significant differences between groups. Strength
for the back squat was considerably greater for HL (HL=19.6 vs. LL=8.8%,)
and significance was also prevalent for the 1RM bench press (HL=6.5 vs.
LL=2.0%). Upper body muscle endurance was assessed via the bench press
at 50% 1RM to failure and LL was vastly significant in comparison to HL
(LL=16.6% vs. –HL=1.2%) (See figures 1,2,3,4) (Schoenfeld et al., 2015). The
literature supports the hypothesis of Hoeger & Hoeger (2016) as both HL
& LL groups achieve the same amount of volume, but instigate either
types of hypertrophy; HL and lower repetitions results in sarcoplasmic
hypertrophy and LL and higher repetitions in myofibrillar.
Figure 1 Significance in both HL & LL groups for muscle thickness increase in the elbow

15
flexors from baseline to post via ultrasound imaging (HL=5.3 vs. LL=8.6%,) (p < 0.01)
(Schoenfeld et al., 2015)
Figure 1.1 Significance in both HL & LL groups for muscle thickness increase in the elbow
extensors from baseline to post via ultrasound imaging (HL=6.0% vs. LL=5.2%,) (p <0.05).
(Schoenfeld et al., 2015)

16
Figure 1.2 Significance in both HL & LL groups for muscle thickness increase in the
quadriceps femoris from baseline to post via ultrasound imaging (HL=9.3% vs. LL=9.5%,)
(p <0.05) (Schoenfeld et al., 2015)
Figure 1.4 Significant differences in 1RM bench press from baseline to post
(HL=6.5%=sig. vs. LL=2.0%=non-sig. )(Schoenfeld et al., 2015)

17
Figure 1.3 Significant differences in 1RM back squat from baseline to post
(HL=19.6%=sig. vs. LL=8.8%=non-sig.) (Schoenfeld et al., 2015)

18
Figure 1.5 Significant differences in muscular endurance from baseline to post
(HL=0%=non-sig. vs. LL=2.0%=16.6%=sig.). (Schoenfeld et al., 2015)
Muscle fibers are the cells of which make up muscle and are of three
different types (Type I, Type IIA, Type IIB), each type plays is responsible
for different muscle functions. Invidividual muscles are made up of
individual muscle fibers that are formed into motor units within each
muscle (Katch et al., 2010). Type II fibers (fast-twitch), grow at a faster rate
than type I fibers (slow twitch) (Aagaard et al., 2001). The rate of muscle
contraction in Type II fibers is also of a greater rate, which means that they
possess a higher strength and power potential than type I fibers (Harber
and Trappe, 2008). Evidence suggests, that no significant differences are
observed in the proportions of muscle fiber types between untrained and
resistance trained individuals (Fry et al., 2003; Ogborn and Schoenfeld,
2014).
2.1.2 Effects of Resistance Training on Recovery
Resistance training is a modality of exercise that is vastly beneficial but
heavily taxing on the body requiring adequate nutrition and a minimum of
48 hours of rest before training the particular muscle group(s) again,
although a full muscle recovery could take up to several weeks (Hausswirth
and Mujika, 2013; Hoeger and Hoeger, 2016). After a resistance based

19
training session there is minuscule damage or tears to the muscle cells and
a break down of the muscle fiber, which is known as catabolism (Bean,
2015; Stone et al., 2007). After the catabolism occurs, the body works
through a cellular process where the muscles fibers conjoin to produce
new muscle protein strands or myofibrils that increase in thickness and
quantity – resulting in myofibrillar hypertrophy (muscular enlargement) and
an increase in the cross-sectional area (CSA) of the existing fibers (Baechle
and Earle, 2008).
Post-exercise recovery and hypertrophy are only effective through
adequate rest and nutrition (Lanham-New, 2011). Insufficient rest can lead
to overtraining which can trigger an increase in cortisol levels and decrease
in dehydroepiandrosterone (DHEA); the body’s long-acting stress
hormones (Constantini and Hackney, 2013; Jenkins, 2005). DHEA and
cortisol are to some extent antagonists to one another; DHEA has anabolic
properties whereas cortisol has a catabolic influence on the body; these
hormones should remain balanced. The sudden imbalance (due to lack of
rest) of these hormones may lead to the following effects: Reduction of
protein synthesis, reduced growth hormone (GH) release, vitamin
depletion, compromised immune function and disrupted sleep patterns –
all of which will have a further adverse impact on recovery and anabolism
(Hausenblas and Rhodes, 2016; Kitaeff, 2011; Seifter et al. , 2005).

20
Fallon and Gerrard (2007) reported that athletes and coaches expressed
that the number one factor for fatigue or tiredness was sleep (Fallon and
Gerrard, 2007). Most athletes suffer from sleep deprivation prior to an
event for numerous reasons, including noise, light, anxiety, and
nervousness (Fullagar et al., 2015). Sleep deprivation can cause downward
changes in glucose metabolism and neuroendocrine function. Furthermore,
lack of sleep or partial sleep may result in alterations in carbohydrate
metabolism, appetite/food intake and protein synthesis harnessing a
detrimental effect on recovery and performance, especially for resistance
athletes who seek anabolic responses (Chittora et al., 2015; Knutson et al.,
2007). These factors could be detrimental to an athlete’s nutritional,
metabolic and endocrine status (Halson, 2014). Sleep is the foundation to
recovery, particularly in order to instigate anabolism. Other than exercise,
sleep is the most powerful non-pharmacological Human Growth Hormone
(HGH) stimulus. During sleep, a signal is sent to the brain via the pituitary
gland, which then releases HGH into the bloodstream in order for recovery
and restoration of the body (Lee-Chiong, 2008). Oliver et al. (2009) found
that one night of sleep deprivation decreased endurance performance with
limited effect on pacing, cardio-respiratory or thermoregulatory function.
The sleep-deprived group had covered less of a distance than the control
group, however altered perception for the sleep-deprived group was

21
greater within a shorter distance, signifying that altered perception of
effort may be the cause for decreased endurance performance (Oliver et
al., 2009). This suggests that lack of sleep (recovery) can have negative
implications upon athletic performance, although this remains equivocal.
2.2 The Endocrine System
The Endocrine System (ES) is comprised of numerous different glands
throughout the body. The role of the ES is to send signals to the body by
manufacturing and secreting specific hormones (e.g. insulin, growth
hormone, thyroxine), which circulate throughout the body (McDowell,
2011). The nervous system and ES may function cohesively
(neuroendocrinology) (Neal, 2016). Exercise and recovery are both primary
factors in influencing hormonal secretion. During the beginning of an
exercise, the thyroid gland directs hormones in order to regulate heart
rate, blood pressure and body temperature, It is also responsible for the
regulation of neuroendocrine functions such as alertness and focus; the
Adrenal gland is responsible for the release of cortisol and controls the
blood pressure, glucose and acts as an anti-inflammatory agent as well as
reacting to emotional responses (i.e. sporting event); the Pancreas secretes
insulin (responsible for directing glucose for energy to the muscles and
tissues that require it) and glucagon (helps breakdown of glycogen to

22
glucose into the liver) (Amitrano and Tortora, 2012; McArdle, et al., 2010).
Athletes are increasingly using ergogenic aids, particularly in nutrition, the
effects of many supplements or ergogenic aids are related to hormonal
response and can influence hormone secretion. Hormonal secretion is of
huge significance in athletic performance; the significance of hormones in
sport and exercise can be related to doping and the usage of performance
enhancing drugs, which imitate androgenic hormones known as anabolic
steroids; hormones are fundamental in their influence in sport and exercise
science (Jameson and De Groot, 2015).
2.2.1 Hormonal Response To Resistance Training
The exercise-induced growth hormone response (EIGR) is of course the
counterpart to sleep in being the major non-pharmacological anabolic
stimulus for hG, although the specific mechanisms of exercise that trigger
this remain equivocal; direct stimulation, nitric oxide and lactate appear to
be the primary elicitors (Clelland, 2011). Resistance training prompts a
significant EIGR, however, protein synthesis has predominantly been due to
IGF-1 with a diminutive contribution from the hGH-GH receptor interaction
on the cell membrane (Ritsche et al., 2014).

23
In males, testosterone is the primary and major circulating androgenic
steroid, which is secreted more than 95% by the testis, producing
approximately 6-7mg per day (Nieschlag and Behre, 2012). The role of
testosterone in male resistance athletes is of great significance as it
triggers GH responses in the pituitary gland, which influences protein
synthesis in muscles for hypertrophy (Scanlon and Sanders, 2014). The
International Rietjens et al. (2015) analysed the effect resistance training
induces on the circulating testosterone response. Four resistance training
protocols were followed and total volume of work was held constant:
moderate intensity (70% 1RM) upper body (bench press, bent barbell row,
and military press), moderate intensity lower body (squat and deadlift),
high intensity (90% 1RM) upper body, high intensity lower body. Both
upper and lower body for moderate intensity resistance protocols resulted
in a significant increase of testosterone concentration (p=0.026, and
p=0.024), whereas the high intensity protocols increased testosterone but
had no significance (upper p=0.272, lower p=0.658) (Rietjens et al., 2015).
In contrast, Ahtiainen et al. (2015) investigated the effects of resistance
training on testosterone metabolism in younger (n = 5, 28 ± 3 yrs.) and
older men (n = 8, 70 ± 2 yrs.) performing heavy 5x10RM leg presses
before and after 12 months of resistance training. The results of this study
found that there was no effect on testosterone metabolism due to
resistance training in either age group (Ahtiainen et al., 2015); Similarly,

24
Molsted et al. (2014) investigated the effects of testosterone and resistance
training on male dialysis patients who performed HL leg press, leg curl and
leg extensions thrice weekly; the study concluded that testosterone values
remained normal (Molsted et al., 2014). Although these studies conclude
reciprocally, Shaner et al. (2014) analysed the contrasting acute effects on
hormonal response via free weight and machine weight RT and discovered
that testosterone levels were significantly higher on the squat versus the
leg press (Shaner et al., 2014). The literature is equivocal, but suggests that
hormonal responses and testosterone increments could be exercise-
type/intensity specific.
West et al. (2009) compared the effects of a high-trial 2 (HH) versus low
hormone (LH) state-trial 1, using a single exercise trial to determine which
had a greater effect on protein synthesis of the bicep brachii. This study
consisted of two trials. To trigger a significant hormonal response, a bicep
curl was performed in the other arm followed by five sets with 10
repetitions of leg press at ∼90% of 10RM and three sets of 12 repetitions
of leg extension/leg curl ‘supersets’ (1 set of each back-to-back with no
rest between sets). Rest periods in between sets were 120s and 60s, for
bicep curl and leg exercise superset, respectively. No changes were
observed in serum testosterone, GH or IGF-1 after the LH protocol,
however there were elevations after HH. Exercise prompted a rise in

25
muscle protein synthesis in the biceps brachii in both groups, but no effect
of elevated hormones (West et al., 2009). Similarly, West & Phillips (2010)
used the same exercise protocol for LH and HH state, but extended to 15
weeks. Identical to the previous study, results showed that the HH group
had a significant increase of serum testosterone, GH or IGF-1 post exercise
compared to the LH group. An increase of 78% in Myofibrillar protein
synthesis was found for the LH group and 61% for the HH group. Between
both groups, no differences were observed for 10RM strength and 1RM
strength. There was also a significant difference in increase of Maximal
Voluntary Contraction between groups (LH 20±4%, range 3%-49% vs. HH
19±3%, range 2-34%), and no difference in CSA between groups. (LH:
12±2% % HH: 10±2%). The results of this study indicate that 15 weeks of a
bicep curl in a LH state is more effective than completing a bicep curl in a
HH state (West & Phillips, 2010).
2.3 Limitations Of Strength & Recovery– Peripheral Factors
2.3.1 Physiological Response To Specific Exercise Movements, Intensity
& Duration

26
The measurement of strength can be subjective due to many direct and
indirect physiological factors from biological (age and recovery) to
chemical responses such as endocrine status, which are relative to one
other, respectively. Shaner et al. (2014) found that testosterone levels were
significantly greater on the squat versus the leg press. Although both
exercises stimulate the targeted muscles, they do not have the same
impact on the central nervous system (CNS). It is believed that increases in
muscle mass, strength and hormones can only occur via the CNS, not the
stress nor load imposed on the muscle (Plowman and Smith, 2011). The
CNS works via the brain and spinal cord and interacts with the muscles
through the peripheral nervous system. The CNS controls the muscle fibers
by propelling a signal to the brain and spinal cord, which connect to the
individual muscle motor units via the neuromuscular junction, causing
muscular contraction. (Raven et al., 2012; Rhoades and Bell, 2009)

27
Figure 2 Diagram showing major divisions of the nervous system (Plowman and Smith,
2011)
Escamilla et al. (2001) reported that both narrow and wide stance
variations of the squat resulted in greater rectus femoris, vastus lateralis,
vastus medialis, lateral hamstring, medial hamstring, and gastrocnemius
activity than narrow (low foot placement) and wide stance (high foot
placement) variations of the leg press. Similarly, found that there was
greater activation of the medial deltoid on the free weight bench press
than on the Smith machine bench press.). The literature would suggest that
strength testing is inconsistent, as exercises must be similar in energy
demand, intensity, muscular recruitment and activation of the CNS in order

28
to produce rational results and physiological responses (Escamilla et al.,
2001; Schick et al., 2010)
2.3.2 Recovery And Restoration
Sleep is generally distinguished as the prime component of recovery, and
general consensus is that sleep is a necessity in order to restore and
replenish the body to its most optimal state. According to the
aforementioned literature, sleep is known as the major non-
pharmacological HgH stimulus; hypertrophy is dependent on HgH and the
level of HgH . Ritsche, Nindl and Wideman’s (2014) study on Exercise-
Induced growth hormone during acute sleep deprivation (SLD) found that
early morning resting GH concentration was unchanged by sleep
deprivation, and exercise-induced GH area under the curve (168%), peak
GH concentration (123%) and Δ GH (122%) were significantly greater after
a night of sleep deprivation (see figure 3) (Ritsche, Nindl and Wideman,
2014). Similarly, HajSalem et al. (2013) investigated the effect of partial SLD
at the end of the night on anaerobic performances during the Wingate
test (peak (PP) and mean (MP) power) and the hand grip (HG) test in 21
judokas; it was discovered that strength decreased and Rated Perceived
Exertion (RPE) was non-significantly affected by partial SLD. Partial SLD

29
reduced muscle power during the Wingate test and did not affect muscle
strength during the HG test (HajSalem et al., 2013). The aforementioned
studies would suggest that the relationship between sleep and HgH is
equivocal and that hypertrophy may not be entirely dependent on sleep.
Figure 3 Mean GH concentrations at each time point between SLEEP and SLD sessions
during exercise and recovery. (Ritsche, Nindl and Wideman, 2014)
2.4 Ergogenic Aids – Nutritional Intervention Strategies
Ergogenic (from Greek) is defined as “work creating”. Therefore, ergogenic
aids have the common characteristics of increasing the rate of work (i.e.

30
sport or exercise performance) (Stone, Stone and Sands, 2007). Many
ergogenic aids become popular due to the success of an athlete that uses
and/or endorses the product (Kraemer, Fleck and Deschenes, 2011).
Athletes are growingly looking for nutritional interventions to further
enhance their performances and coaches are recommending them to do
so (Gregory and Travis, 2015). Supplement manufacturers claim that
athletes require these nutritional aids to increase performance because the
substances are either unavailable through a normal diet or are required in
greater amounts than the body can acquire through regular dietary habits
(Pfeiffer et al., 2014).
2.4.1 Zinc Aspartate
Zinc (Zn) is a trace mineral responsible for the reproduction of cells,
regeneration of tissue and wound recovery, sexual maturity, and optimal
growth. Zn is a needed for various enzymatic functions throughout the
body, and also aids in regulating the immune system and insulin
metabolism. Preferably, the dosage of zinc included is from 2 to 30 mg as
Zn Aspartate (Slaga et al., 2002). A feature of Zn concentration in the

31
human body is its localisation; the male reproductive system is a zone of
high Zn concentration; Zn is a hormonal trigger (Mills, 2013).
2.4.2 Magnesium Aspartate
Magnesium is a mineral essential for all biological processes including the
metabolism of glucose, protein and nucleic acid synthesis, electrical
balance of cells, and the transmission of nerve impulses. Magnesium has
an effect on the heart and its functions, structure integrity and
contractions, and all other muscles. Preferably, the dosage of magnesium
included is from about 10 to about 500 mg as Magnesium Aspartate
(Slaga et al., 2002).
2.4.3 Vitamin B6
Vitamin B6 is a general term for the group of three vitamins: pyridoxine,
pyridoxal and pyridoxamine. They are significant in protein and amino acid
metabolism and aid in regulating blood glucose levels. These vitamins are
required to synthesise hemoglobin and are central in the optimal function
of the CNS. The dosage of vitamin B6 is preferably from about 200 mcg to
about 3 mg (Slaga et al., 2002).

32
2.4.4 Role Of ZMA & Effect on Strength & Recovery
ZMA supplementation has gained popularity and recognition for being
marketed as a “natural testosterone booster”. In an age where steroid
usage is prevalent amongst the general public, as well as mainstream
sport, elite athletes are searching for legal and natural ergogenic aids to
enhance performance (Beamish, 2011). Vitamin B6 is included in the
formulation to aid the uptake and utilisation (metabolism) of Zn & Mn, not
as an ergogenic factor (Greenwood, Kalman and Antonio, 2015). Studies
that have clinically trialled ZMA have been contrasting, although a lot of
the literature would suggest that the marketing behind the supplement
could be substantiated by scientific evidence.
Brilla & Conte (2000) used A ZMA capsules (30 mg zinc monomethionine
aspartate, 450 mg magnesium aspartate, and 10.5 mg vitamin B-6) to test
the effects on hormones and strength on 57 varsity football players. All
subjects took three capsules nightly between dinner and bedtime. The
results of this study showed that the ZMA group increases significantly
differed from the placebo group. There was a 10%-range increases in

33
quadriceps torque and 12.7% to 15.2% increases in quadriceps power for
ZMA supplementation in comparison to the -0.8% to 2.4% change in
quadriceps torque and 8.6% to 10.8% change in quadriceps power for the
placebo group. As a result of randomization, baseline differences were
observed in muscle torque and power, which resulted in higher values for
the placebo group versus the treatment group from the beginning. Both
groups had overall increases in the training and supplementation period,
but the ZMA supplementation resulted in greater increases in comparison
to placebo (Brilla & Conte, 2000). In contrast, Wilborn et al. (2004)
examined the effects of ZMA supplementation on training adaptations in
42 resistance-trained athletes. Results of this study conveyed that no
statistically significant changes were observed between groups in mean
bench press 1-RM (P 3.6 ± 5.5 kg and ZMA 5.6 ± 5.9 kg, p = 0.24), leg
press 1-RM (P 24.6 ± 25 kg and ZMA 25.4 ± 32 kg, p = 0.92), bench press
lifting volume (P -51 ± 206 kg; ZMA 4 ± 186 kg, p = 0.38), or leg press
lifting volume (P 480 ± 1,022 kg; ZMA 724 ± 1,258 kg, p = 0.48) (Wilborn
et al., 2004). Both of these studies show antagonistic results to one
another, however both have a sense of equivocality due to the participants,
as they have dissimilar sporting/athletic backgrounds and experience of
strength training, as resistance-athletes are more disposed to strength
training protocols.

34
Sheykh & Bordbar (2012) studied the effect of ZMA supplementation
singularly and in combination with carbohydrates, with six weeks of
resistance training on anabolic hormone levels in 27 untrained males.
Despite the relative increase in anabolic hormones in the supplement
groups, no significant differences were observed between the three groups
in serum testosterone and IGF-1 levels. Conversely, ZMA supplementation
with resistance training resulted in a significant increase in bench press
1RM strength in all 3 groups (Sheykh & Bordbar, 2012). Likewise, Moëzzi,
Peeri and Homaei, (2014) looked at the effects of zinc, magnesium and
vitamin B6 supplementation on hormones and performance in weightlifters
by investigating military press strength and squat strength. Shoulder
strength in military presses in ZMA and dextrose groups increased
significantly by 8.3% and 7.78%, respectively. Squat strength significantly
increased by 4.9% and 3.56% in ZMA and dextrose groups, respectively,
but there was no significant difference in squats records before and after
training course in both supplement groups. The findings of the hormonal
response showed that there were significant differences in the rate of total
testosterone (p=0.695), free testosterone (p=0.379), cortisol (p=0.346) and
ratio of testosterone to cortisol (p=0.718) (Moëzzi, Peeri and Homaei,
2014). These results show that ZMA increases strength, however, there are
dissimilar results for hormonal response.

35
Abbasi et al. (2012) analysed the effects of Mn supplementation on
primary insomnia in 46 elderly subjects. Findings showed that Mn
supplementation appears to improve subjective measures of insomnia such
as ISI score, sleep efficiency, sleep time and sleep onset latency, early
morning awakening, and likewise, insomnia objective measures such as
concentration of serum renin, melatonin, and serum cortisol, in elderly
people (Abassi et al., 2012). Similarly, Abassi et al. (2013)’s study analysed
the effect of Mn supplementation on the physical activity of 46 overweight
insomniac subjects using 500mg of Mn. The results of this study concluded
that there were no significant differences observed in assessed variables
between the two groups at baseline. But results showed that Mn
supplementation significantly increased sleep indices and physical activity
level (Abassi et al., 2013). Mn is clearly suggested to improve the quality of
sleep, which would support the proclamation of ZMA’s recovery properties.
Kass and Poeira (2015) found that 1-RM bench press strength showed a
significant increase of 17.7% compared to baseline, with acute Mn (300mg)
supplementation. No significant strength gains were observed in the
chronic intervention group (Kass and Poeira, 2015). Literature on Mn and
strength/resistance training is generally limited, however, the findings of
Kass and Poeira (2015) are very noteworthy when discussing the effects of
Mn as a synergist in the ZMA supplement.

36
Shafiei et al. (2011) studied the effect of Zinc and Selenium
Supplementation on Serum Testosterone in 24 cyclists after one bout of
exhaustive exercise. The particpants were divided into four groups;
placebo; Zn group (30 mg/day); selenium supplement (Se) (200 μg/day);
and Zn-Se group. Results revealed that Zn supplementation increased
levels of total testosterone in comparison with Se group, and also
increased free testosterone versus the other groups (Shafiei et al., 2011). In
contrast, Femiano & Morris (2015) discovered that ZMA supplementation
with a 90–120 mg zinc component (greater amount than common ZMA)
for 7 to 8 weeks in 17 previously active men did not increase serum
testosterone levels (Femiano & Morris, 2015). Although contrasting and
equivocal, the opposing results of these studies would vaguely suggest
that Zn could have testosterone enhancing properties, although this may
not be the case. It is also worth noting that the dosage amount may have
had an impact on these results.
Previous research on strength using ZMA as a combined formula (30 mg
zinc monomethionine aspartate, 450 mg magnesium aspartate, and 10.5
mg vitamin B-6) is mostly archaic and limited; literature on each
component of ZMA as singular supplements (Zn and Mn) is readily
accessible. The suggestion is that Mn improves sleep, which could
rationalise the recovery properties of the ZMA supplement and Zn

37
improves testosterone, which would rationalise the anabolic properties, yet
this remains ambivalent and needs to be looked into more depth.
2.5 Dosage, Administration & Timing
2.5.1 Dosage & Safety For Human Consumption
ZMA is a supplement that is commonly distributed and used in capsule
form. Numerous studies on ZMA use capsules (serving size of 3) containing
11 mg of Vitamin B-6 (pyridoxine hcl), 450 mg of magnesium (as
magnesium aspartate), 30 mg of zinc (as aspartate), all in accordance to
the recommendation stated by Slaga et al., (2002) and affirmed by the
National Insititute of Health (2016) (National Institute of Health, 2016;
Slaga et al., 2002). Studies have also shown the aforementioned dosage
amount to increase anabolic hormone levels and muscle strength in
trained athletes. (Brilla & Conte, 2000; Koehler et al., 2007; Koehler et al.,
2009; Wilborn et al., 2004). No side effects were observed during previous
studies and affirm that the supplement is safe for human consumption.

38
2.5.2 Timing
The aforementioned studies asked participants to take the ZMA
supplement on an empty stomach 60 minutes prior to sleep; 3 capsules,
once nightly (Brilla & Conte, 2000; Koehler et al., 2007; Koehler et al., 2009;
Wilborn et al., 2004). Ingesting the supplement approximately 60 minutes
before bed will optimise its uptake and utilization and enhance sleep
quality as magnesium can normalise and extend stage 3 and 4 slow-wave
sleep (Pizzorno and Murray, 2013).
2.5.3 Performance Measures & Test Reliability
Bampouras et al. (2014) evaluated the Test-retest reliability and sensitivity
of the Concept2 Dyno dynamometer using 46 competitive male athletes.
Reliability was evaluated by examining systematic bias, intraclass
correlation coefficient, coefficient of variation (CV), and 95% limits of
agreement (LoA). Each experimental trial comprised of 3 maximal efforts
across the three exercises; chest press, diverging row and leg press. No
systematic bias was discovered for any of the exercises. Intraclass
correlation coefficients were high (0.89-0.98) with relatively low CV (6.2-
4.3%). 95% LoA suggested that subsequent testing could underestimate by
a factor of 0.87 or overestimate by a factor of 1.17, on average. These

39
results indicate that Concept2 Dyno dynamometer is reliable and can be
used to efficiently assess strength performance (Bampouras et al., 2014).
Numerous studies have used the Concept2 Dyno dynamometer in strength
research (Cronin et al., 2014; Grujic et al., 2013 Lawton et al., 2013; Lawton
et al., 2013; Popadic Gacesa et al., 2012).
Table 2 Descriptive statistics (mean ± SD) for the seated bench press, seated bench pull,
and seated leg press from the 3 trials for both the whole sample and the subsample.*†
Table 3 Reliability and sensitivity statistics for all exercises between trials, for both the

40
whole sample and the subsample.*‡
2.6 Summary of Literature
Resistance training holds many health and physiological benefits such as
elevating hormone levels and increasing hypertrophy & muscle CSA
(Ehrman et al., 2013). The strenuous demands of resistance training
requires athletes to turn to ergogenic aids in order to replenish the body

41
post exercise and to enhance and maximise general performance.
Ergogenic aids are becoming ever in demand, although there is always
uncertainty about their effects. The aim of this study was to determine
whether a 28-day chronic ZMA supplementation would improve 1RM
strength and recovery in resistance athletes.
ZMA is a synergistic supplement made up of Zinc (Zn) (30mg), Magnesium
(Mn) (450mg) and vitamin B6 (10.5mg). Each one of the synergists of the
ZMA formulation plays a collaborative role in the ergogenic effects the
supplement is believed to possess. It is marketed to possess ergogenic
benefits, primarily increasing testosterone levels, although literature is
conflicting and equivocal. West et al. (2009) and West & Phillips (2010)
concluded no significant differences were observed in muscle protein
synthesis and CSA when comparing high hormonal state participants
versus low hormonal state, these findings are significant as ZMA is said to
be a hormone stimulator.
Brilla & Conte (2000) found a significant increase in hormone levels and
leg strength, but this was negated by the study of Wilborn et al. (2004),
which found no significant increase of hormone or 1RM-strength for bench
press and leg press. Other studies on ZMA have found significance in
squat strength (?) and bench press strength, but no significant differences

42
were observed in hormone levels. Literature on ZMA as a whole
supplement is very minimal and generally out-dated, however, literature is
more readily available for its synergist components Zn & Mn. Abassi et al.
(2012) and Abassi et al. (2013) have found that Mn improves sleep and
Kass and Poeira, (2015) found Mn to improve 1-RM bench press strength.
Zinc has been suggested to improve free and total testosterone levels,
according to the results of a study by Shafiei et al. (2011). However,
these findings contradict the findings of Femiano & Morris (2015),
where no increases of serum testosterone levels were observed with a
higher dosage of Zn.
The suggestion from the literature is that Mn improves sleep, which could
rationalise the recovery properties of the ZMA supplement and Zn
improves testosterone, which would rationalise the anabolic properties, yet
this remains ambivalent and needs to be looked into more depth.
2.7 Specific Research Aims
This study was undertaken with the following specific research aims:
1. The primary aim of this study was to analyse and evaluate the
effects of a 28-day ZMA supplementation load versus placebo

43
(Maltodextrin) on 1RM strength performance (kg) across 3
movements: chest press, diverging row, leg press.
The additional research aim(s) when conducting this study included:
2. Evaluate the effects of a 28-day ZMA supplementation load on
acute recovery (sleep) across 3 variables: duration of sleep (hours),
awakenings, and quality of sleep (Likert scale).
3. Evaluate the mechanisms of strength and hypertrophy, and the
relationship with recovery.
2.8 Research Hypothesis
Hypothesis 1:
HA
1= There will be a significant interaction effect (pre versus post
supplementation) in strength (kg) for the chest press following 28-days of
ZMA supplementation in contrast to Placebo.

44
HN
1 = There will be no significant interaction effect (pre versus post
supplementation) in strength (kg) for the chest press following 28-days of
Hypothesis 2:
HA
2 = There will be a significant interaction effect (pre versus post
supplementation) in strength (kg) for the diverging row following 28-days
of ZMA supplementation in contrast to Placebo.
HN
2 = There will be no significant interaction effect (pre versus post
supplementation) in strength (kg) for the diverging row following 28-days
of ZMA supplementation in contrast to Placebo.
Hypothesis 3:
HA
3 = There will be a significant interaction effect (pre versus post
supplementation) in strength (kg) for the leg press following 28-days of

45
HN
3= There will be no significant interaction effect (pre versus post
supplementation) in strength (kg) for the leg press following 28-days of
2.9 Assumptions
This study made the following assumptions:
1. Participants provided a truthful representation on all consent,
medical forms, evidence sheets and questionnaires.
2. Participants followed the supplement protocol and had taken the
given and required amount accordingly to fulfil the demands of the
study during the 28-day period.
3. Participants completed their individual sleep diaries and gave a true
representation
4. Participants followed all instructions and demonstrations provided
by the experimenter.

46
5. Participants gave their truest representation maximal effort in pre
(baseline) and post testing.
The following assumptions were made as participant’s information, data
and results were secured with anonymity and confidentiality. Volunteers for
the study also had the right and freedom to withdraw from participation at
any given time without any justification or ramifications.
2.10 Delimitations
1. Participants of the study had not consumed any ergogenic aids
containing creatine, glutamine, arginine, HMB, androstendione,
thermogenics, or any other ergogenic supplement at the time of
study (or in the last 6 months).
2. Participants had not resistance trained 48 hours prior to testing.
3. All participants were resistance-trained athletes aged between 18-28
in healthy physical condition, and participating in a resistance based
exercise programme a minimum of thrice per week.

47
4. Duration of the study was a maximum of 7 weeks per participant,
including a 28-day supplement load, and a 3-day sleep diary before
and after the 28-day period.
2.11 Limitations
1. The inability to control physical activity (frequency, intensity,
duration)/physical activity hiatus and supplementation adherence
between pre (baseline) and post testing.
2. Participants who have had previous experience with ergogenic aids
may have recognised their supplementation group and that could
have affected consumption and adherence to their maximal effort in
post testing.
3. Recruitment process comprised of resistance athletes of varying
experiences (not specific) from the University of Brighton and The
Gym Group, Brighton.

48
5. The inabilities to control sleep activity (time of sleep, hours slept,
awakenings) and daily schedules and routines, which could have
affected sleep.
3.0 Methods
3.1 Experimental Approach To The Problem
This study was conducted over a 7-week period as a randomised, repeated
measures, mixed, double blind, placebo controlled clinical trial. Each
participant individually attained familiarisation with the equipment
(Concept2 Dyno dynamometer). Participants later participated in baseline
testing (pre) before being randomly assigned to a Maltodextrin placebo
group or ZMA supplement group. A placebo. Participants followed the
experimental design and performed 1RM strength testing procedures on 3
exercises (chest press, diverging row and leg press) using the Concept2
Dyno dynamometer before and after the 28-day supplementation period.
The participants were also informed about and provided with a form for
the 3-day sleep diary (Appendix G), which they were requested to
complete, and hand-in before and after the supplementation period. It was
hypothesised that chronic ZMA supplementation would have a significant
effect on 1RM strength and recovery (sleep) in the ZMA group compared
to the placebo.

49
3.2 Participants
Fourteen resistance-trained male subjects participated in this study.
Candidates were recruited verbally from The University of Brighton and The
Gym Group, Brighton. Subjects were excluded from the study if they were
not actively participating in resistance exercise at least 3 times a week;
have suspended training due to current or reoccurring muscular or joint
injuries; were diagnosed with cardiovascular, pulmonary or medical
disorders and/or disease; had abnormal heart rate or blood pressure;
and/or had been recently instructed by a physician or doctor not to
participate in any form of resistance exercise, in accordance to the ACSM
screening guidelines (ACSM.org, 2016). Candidates were also disregarded
for participation if they were currently (or in the last 6 months) taking any
ergogenic aids containing creatine, glutamine, arginine, HMB,
androstendione, thermogenics, or any other ergogenic supplement
(Wilborn et al., 2004). Prior to initial testing and recruitment, candidates
were provided with a participant information sheet (Appendix A), which
provided a detailed insight and overview into the study and study
background. Candidates meeting the eligibility criteria were informed of
the requirements of the study and signed an informed consent (Appendix
B) and medical questionnaire (Appendix C & D) in compliance with the

50
Guidance on Good Practice in Research Ethics and Governance of
University of Brighton (University of Brighton, 2016). Candidates who were
selected for participation were asked to refrain from any caffeinated drinks,
pills or tablets 48 hours prior to testing, as caffeine has been suggested to
have an ergogenic effect on strength performance (H Brooks and Wyld,
2015); candidates were further asked to refrain from resistance training 48
hours prior to testing to ensure optimal performance. Subjects were
descriptively 22.9 ± 2.9 years; height 180 ± 4.7 cm; 83.6 kg ± 9.4 body
mass. Candidates were assured that all informed data would be
confidential and withdrawal of participation was allowed at any given time
without justification or any ramifications. This study was overlooked and
approved by The University of Brighton ethics committee.
Supplement Age (Years) Height (cm) Weight/Mass
(kg)
Maltodextrin
[Placebo] (n =
7)
23. 4 ± 3.3 180 ± 6 85.6 ± 9.8
ZMA (n = 7) 22.4 ± 2.2 180 ± 2.8 81.6 ± 8.4

51
3.3 Experimental Procedure
Pre-testing involved recording the anthropometric measures of the
participants; age (years); height (cm); weight/body-mass (kg) recorded prior
to familiarisation and baseline testing. Participants attended each lab
session between 9am-12pm on either occasion. Familiarisation included a
demonstration and explanation prior to participants operating the
Concept-2 Dyno dynamometer. Participants were randomised into either
group (Placebo/Group A or ZMA/Group B) using an online research
randomizer (Randomizer.org, 2016). There were 4 weeks between pre
(Baseline) and post (Placebo/ZMA) supplementation testing periods. Post
testing took place within a week after the 28-day supplementation period
to avoid development of washout. Baseline and post-supplementation
experimental procedures were identical. Empty bags (dispenser) of the
supplements were handed in after the post-supplementation period to
determine the usage of the supplement and to ensure that participants
complied (Wilborn et al., 2004). A number of studies have validated
beneficial effects following an identical 28-days, pre-exercise
supplementation protocol (Ormsbee et al., 2012; Shelmadine et al., 2009).

52
Figure 4: Schematic of Experimental Procedure from Baseline to Post
The testing procedure consisted of assessing the 1 rep max (1RM) on the
chest press, diverging row and the leg press (kg) (Appendix E). Participants
performed 3 reps at a minimal-maximal exertion effort: 25% (minimal), 50%
(medial) 100% (maximal – 1RM). There was a static-recovery period of 5
minutes in between exercises in order for the body to return to its pre –
exercise state (Porcari, Bryant and Comana, 2015). The exercises were
performed in the following order; chest press; diverging row; leg press,
respectively. Each rep was performed with a delayed eccentric motion of
approximately 3 seconds in order to optimally increase the mechanisms
relating to strength via time under tension (Hoffman, 2014), and exploding
during the concentric phase at maximal speed as it optimises the response
of the CNS (Bartlett and Bussey, 2012).

53
Figure 5: Schematic of Exercise & Testing protocol
3.3.1 3-Day Sleep Diary
Participants were requested to record a 3-day sleep diary before and after
the supplement load period. The sleep diary was structured using previous
literature and an identical protocol to Karolinska Sleep Diary (Akerstedt et
al., 1994), however variables were condensed and made relevant to the
present study (Lichstein et al., 2007; Lin et al., 2011). The variables
recorded were; hours of sleep; awakenings; and quality of sleep on a likert
scale of 1-10 (1 representing the poorest quality and 10 representing the
greatest quality).
3.4 Supplementation
The study design consisted of a placebo-controlled, double blind clinical
study. The supplementation period commenced after preliminary (baseline)

54
testing and once 3-day sleep records were collected from participants.
Participants were randomised for allocation into either group A (placebo-
controlled group; Maltodextrin) or group B (ZMA supplement group). The
supplementation load was a 28-day period with supplements ingested
orally (3 capsules). Supplements were dispensed in sealed bags.
Participants were informed to ingest 3 capsules on a nightly basis, on an
empty stomach 60 minutes prior to sleep. Subjects were requested to
report any possible side effects (such as tingling) that may occur during
the supplementation period (Insel et al., 2015).
3.5 Statistical Analysis
Data collected from the study was reported and presented as means
(±SD), unless otherwise stated. Three two-way mixed design repeated
measures ANOVA’s [2x3; Time (Pre versus Post x Condition aka Treatment
or Supplementation (Placebo versus ZMA)]. Data normality, homogeneity,
and specificity were assumed with a significance level of P<0.05. Post-Hoc
analysis was used in order to analyse any reported statistical effects found
within the data output. Three separate repeated measures ANOVA
(significance P<0.05; Bonferroni correction) were used on each group and
test to determine differences in fourteen separate strength outputs. All

55
statistical analysis was conducted using SPSS version 22 software. For all
statistical analyses α level of P ≤ 0.05 was accepted as significant.
4.0 Results
The 14 participants completed the pre and post supplementation testing.
The participants adhered to completing the sleep diaries, and the returning
empty supplementation dispensaries showed that all subjects had followed
the requested supplementation protocol accordingly. Compliance of
protocols was reciprocally corresponded to the assumptions, resulting in all
collected data to be used in the statistical analysis. The inferential
statistical analysis outcomes were reported with descriptive data sets
reported as mean (±SD).
A Two Way mixed-design repeated measures ANOVA was run to test for
an interaction effect between time (pre/post) and supplementation group
(placebo/ZMA) on strength (kg) across each of the three exercises; chest
press, diverging row and leg press.
4.1 1RM Performance On Strength

56
Table 4: Changes in strength pre & post supplementation. Compared means are
represented as SD
Placebo (n = 7) ZMA (n =
7)
Before After
∆ Before After
∆
Age (y) 23.4 ± 3.3 N/A N/A 22.4 ± 2.2 N/A N/A
Height (cm) 180 ± 6 N/A N/A 180 ± 2.8 N/A N/A
Body Mass (kg) 85.6 ± 9.8 N/A N/A 81.6 ± 8.4 N/A N/A
Chest Press (kg) 82 ± 22 82.7 ± 22 0.7 ± 0 88.6 ± 29.6 91.7 ± 31.7 3.1 ± 2.1
Diverging Row
(kg)
91.3 ± 35.7 91.1 ± 19.5 -0.2 ± 16.2 98.6 ± 25.4 98.1 ± 28.1 -0.5 ± 2.7
Leg Press (kg) 146 ± 25.2 146.1 ± 26.1 0.1 ± 09 147.3 ± 32.1 †155.4 ± 33.2 8.1 ± 1.1
† = P ≤ 0.05, significantly different from before values.
Chest Press - ANOVA did not find a significant interaction effect between
time (pre & post) and supplement (PL & ZMA) for strength on the chest
press with ZMA: F (1,12) = 1.96, P = 0.187. Therefore, the alternate
hypothesis (HA
1) can be rejected.
Diverging Row - ANOVA did not find a significant interaction effect
between time (pre & post) and supplement (PL & ZMA) for strength on

57
the diverging row with ZMA: F (1,12) = 0.02, P = 0.884. Therefore, the
alternate hypothesis (HA2) can be rejected.
Leg Press: - ANOVA found a significant Interaction effect between time
(pre & post) and supplement (PL & ZMA) for strength on the leg press for
ZMA: F (1,12) = 1.96, P = 0.000. Therefore, the alternate hypothesis (HA3)
can be accepted.
Figure 6 displays percentage changes (%) across all movement protocols
for placebo controlled and ZMA group. There was a statistically non-
significant increase of 0.87% in 1RM chest press strength (kg) for the
placebo group & a statistically non-significant percentage increase of 3.5%
for the ZMA group. The percentage changes in the diverging row show
that there was a decrease of -0.16% in 1RM strength for the placebo
group and 0.43% for the ZMA group, respectively. There was a statistically
non-significant increase of 0.10% in 1RM leg press strength (kg) for the
placebo group & a significant percentage increase of 5.5% for the ZMA
group.

58
Figure 6: Mean percentage change (%) pre and post supplementation on 1RM strength.
SD (±) represented by error bars.

59
4.2 Recovery
Figure 7: Mean percentage change (%) pre and post supplementation on sleep (average
hours slept, average awakenings, average quality of sleep) across 3 days. SD (±)
represented by error bars.

60
Figure 7 displays mean percentage changes (%) in average hours slept
(Hs), awakenings and Quality of sleep (QoS) across 3-days (pre and post)
for both supplement groups. The percentage change in the PL group
shows an increase of 14.9% in HS; 5.8% in awakenings; and an increase of
3.1% in QoS. The ZMA group shows an increase of 5.8% in HS, a decrease
of -31.3% in awakenings, and an increase of 22.1% in QoS, respectively.
5.0 Discussion
5.1 Summary of Findings
The aim of this study was to investigate whether 28-days of chronic ZMA
supplementation would improve 1RM strength performance and acute
recovery in recreational male resistance-trained athletes. The primary aim
was to establish if 1RM strength would improve post-supplementation.
Mixed ANOVA reported no significant interaction effect on 1RM with
supplement intervention for the chest press & diverging row, however

61
1RM for the leg press showed a significant increase (P<0.05), therefore HN
3
was rejected. The additional aim of the study was to assess whether
recovery would improve post-supplementation. Findings from the
participants 3-day sleep diaries revealed a post supplement mean increase
of 5.8% for hours slept; a -31.3% mean decrease of awakenings; a 22.1%
mean increase in QoS.
The significant increase of 1RM leg press strength post-ZMA shows that
the supplement could hold some credibility in improving strength,
although this remains equivocal, as there were no significant results for the
chest press or diverging row. ZMA is known for its anabolic properties, and
how it is suggested to improve hypertrophy is via the increase of hormonal
responses. Ahtiainen (2015) and Molsted (2014) both found that resistance
training for exercises targeting the lower limb/leg muscles resulted in no
significant effect or change in hormone levels. If the aforementioned
research were to correspond with the present study, it would suggest that
hormonal responses which trigger hypertrophic processes are not exercise
dependent, thus, the increase of strength in the leg press from the current
study may be either from a peripheral source or perhaps in-fact the effects
of the supplementation. Recovery appeared to be prominent post-
supplementation as all the sleep measures, which were recorded improved
substantially. There was only a slight increase of strength by 5.8%, however

62
the vast increase of awakenings (31.3%) and QoS (22.1%) would suggest
that the increase in hours slept were due to the decrease of awakenings,
thus, resulting in a better-perceived QoS for the participants.
The current study has produced similar results to that of Brilla & Conte
(2000) & Sheykh & Bordbar (2012). Both studies, including the present
study, indicated a significant increase in leg strength, although the findings
from Wilborn et al. (2004) are antagonistic, and observed no significant
improvement in leg strength. Findings from Moëzzi et al. (2014) showed
that ZMA supplementation significantly increased bench press strength; the
current study revealed an increase in chest press strength, however this
was a statistically non-significant result. When comparing the results of
these studies, no clear interpretation can be made, there is no scientific
explanation as to why there was no significant change in the upper body
exercises (chest press & diverging row) but there was with leg press post
ZMA supplementation. Due to the ambiguity of strength significance in the
literature and current study, assessing hormonal responses from previous
literature can provide a clearer interpretation of these findings.
5.2 Differences In Hormonal Responses

63
Moëzzi et al. (2014) found an increase of testosterone levels post ZMA in
comparison to baseline; leading to a 11.42% and 21.36% increase
respectively in free and total testosterone, while the levels of these
hormones in the placebo group showed 6.48% and 21.15% increases,
respectively. The results of Wilborn et al. (2004) support the findings of
Moëzzi et al. (2014). In contrast, Brilla and Conte (2000) reported a 30%
increase in total and free testosterone in the ZMA group, as well as a 10%
decrease in the placebo group. This would support the notion that the
lack of significant differences may be a result of routine training of
participants and since the identical increases were observed in free and
total testosterone levels in both supplement and placebo groups. This
suggests that, although Moezzi et al., (2014) found a significant increase of
1RM strength on the bench press, there was no significant hormonal
response, thus, the strength increase (which is believed to be produced via
anabolic hormone responses) is inconclusive of the ZMA supplementation.
Similarly, the findings from Sheykh & Bordbar (2012) showed a significant
increase of squat strength, however, despite the relative increase in
anabolic hormones in the groups receiving ZMA, no significant differences
between the three groups (ZMA, ZMA & CHO, placebo) in serum
testosterone and IGF-1 levels were observed. Furthermore, the implications
this has for the present study can suggest that, the increase of 1RM leg

64
press strength can be attributed to the effects of regular and continuous
training outside of the study and not ZMA.
5.3 Mechanisms of Hypertrophy
It is generally believed that hypertrophy is primarily instigated through the
increase of anabolic hormones, which, is suggested to be the result of
ZMA supplementation. The studies by West et al. (2009) & West & Phillips
(2010) (See 2.2.1) contradict the general notion that hypertrophy is
primarily hormone dependent, and show that performing a compound
exercise on the same day as assistance exercise will increase in anabolic
hormone production, but with no increase in hypertrophy nor protein
synthesis. Exploring the mechanisms of hypertrophy further, myofibrillar
hypertrophy and protein synthesis are structured entirely upon local factors
that trigger intracellular signaling pathways (Schoenfeld, 2016). Calcineurin
(one of two calcium dependent pathways) dephosphorylates cytoplasmic
proteins, which allows the proteins to transport into the nucleus for gene
transcription (Hill and Olson, 2012; Schoenfeld, 2016). Calcium Calmodulin
Protein Kinase signaling pathway is the second pathway. Similarly to
calcineurin, it is regulated by intracellular calcium, but it is activated by
short intensity high amplitude calcium signals (Borer, 2013). Literature is

65
however equivocal when providing an explanation of the role calcium
calmodulin plays in muscle hypertrophy and phenotype changes.
A review by Tu et al. (2016) discussed evidence with conclusions that
Calcium hydroxide (Ca2+) is an important component of the signaling
promoting muscle formation, muscle homeostasis, and regeneration. In
particular, Ca2+ changes may translocate muscle satellite cells to maintain
their inert state, increase, or separate into functional muscle (Tu et al.,
2016).
The literature would suggest the increase of leg press strength for the
present study or that of Brilla & Conte (2000) might not be attributed to
the effects of ZMA. There are indifferent and inconsistent results for
strength and hormone levels in each ZMA study, current and previous. It
can only be assumed that there are other factors and instigators of
myofibrillar hypertrophy, other than testosterone, GH or IGF-1 (instigated
by ZMA). Peripheral factors for the main findings of the present study will
be discussed in the limitations (See 5.5).
5.4 Critical Analysis
The study by Wilborn et al. (2004) uses a larger sample size of 42
participants, in comparison to that of the current study and that of the

66
study by Moëzzi et al. (2014). The participants in the study by Wilborn et
al. (2004) also have a mean age of 27 ± 9 years in comparison to 22.9 ±
2.9 years for the present study. Age-related changes in skeletal muscle can
be impaired by the normally decreasing levels of physical activity
associated with advancing age and also by metabolic changes and
oxidative stresses that that prompts the accumulation of intracellular
damage from free radicals (Meng & Yu, 2010). Even frequently active elite
athletes and healthy older adults also show a gradual wasting of muscle
mass, loss of strength and power output (Yamauchi et al., 2009).
Furthmore, Age-related changes in circulating muscle anabolic hormones
and growth factors are also prevalent (Lynch, 2011). These factors may
have influenced the results due to the broad range of age of the study by
Wilborn et al. (2004). The exercise protocols in the literature differentiate.
Wilborn et al. (2004) implemented a warm-up protocol and particpants
worked their way up towards the 1RM, whereas Brilla & Conte (2000)
looked at torque and power at different angles, both, which are unrelated
to the methods of the current study. According to Niewiadomski et al.
(2008) 1RM is a reputable and universal measure of muscular strength and
is defined as the amount of resistance against which a given movement
can be performed only in one attempt/repetition. A general evaluation of
1RM is time consuming, and may lead to muscle soreness as well as
temporary weakening of the tested muscles, which can discount accuracy

67
and consistency of further attempts. Attempts at determining 1RM
indirectly based on the maximum number of repetitions performed have
projected 1RM with an adaptable degree of accuracy (Niewiadomski et al.,
2008). This suggests that a build up or several different sets and rep
ranges would have implications on the end output due to weakening and
fatigue of the muscles.
There is no previous literature on ZMA’s effect on recovery, however,
literature for Mn improving sleep (recovery) is readily accessible. Results for
recovery in the current study show notable results as the QoS significantly
increased post-ZMA supplementation, with a significant decrease in
awakenings during the night. Numerous studies have shown that Mn
improves sleep; studies by Abassi et al. (2012) and Abassi et al. (2013) both
observed significant improvements in sleep. Interestingly, Kass & Poeira
(2015) found that acute Mn supplementation at a lower dosage (300mg)
than ZMA (450mg) significantly improves 1RM strength in the bench press.
This could imply that Mn, exclusive of ZMA could have anabolic properties,
although further research is required in resistance athletes and exercise.

68
5.5 Limitations
The current study has various limitations from internal to peripheral
factors, which were not controlled during the supplementation period.
ZMA supplementation alone could not (if effective) induce the
development of hypertrophy and strength. Muscular hypertrophy is
tremendously complex and requires a number of physiological processes
and adaptations (Hall, 2015), dietary intake being one of the foundations
of these, however it was not monitored for the present study. In resistance
training especially, protein intake is an important aspect of muscle
development and functionality and provides the body with essential amino
acids that release HGH in order for muscle hypertrophy to occur
(Rajendram, Preedy and Patel, 2014). Fontana et al. (2008) discovered that
the protein intake and micronutrients of a diet are key determinants of
IGF-1 (Fontana et al., 2008). By not monitoring dietary intake, an
explanation as to why a significant effect has occurred in strength cannot
be explained in greater depth. Furthermore, individual implications on the
study can also not be explained.

69
Schoenfield et al. (2015) & Schoenfield et al. (2016), found that different
variations and durations of repetitions and frequencies of training per
week in resistance training elicited differing levels of muscle hypertrophy
(Schoenfeld et al., 2015; Schoenfeld et al., 2016). Resistance training is an
exercise modality, which induces different responses based on exercise
volume, exercise type, intensity and duration. A study by Netreba et al.
(2013) looked at the responses of knee extensor muscles to leg press
training of various types in human and discovered that fiber hypertrophy,
fatigue resistance and VO2max changes were related to the type of training
(Netreba et al., 2013). Resistance exercise imposes stress upon many of the
metabolic pathways. Resistance exercise may prompt muscle biochemical
adaptations that increase micronutrient needs. Regular exercise may result
in the turnover and losses of these micronutrients, thus, requiring a
substitute of additional micronutrient intake in order for the body to
function, repair and grow (Driskell and Wolinsky, 2016). Training programs
were not monitored or controlled for the study and may have had
implications on the results.
Individual differences, muscular structures, CSA and fiber-type determine
how much force is exerted, as force generation capacities differ (Katch et
al., 2010). According to Aagaard et al. (2001) Type II fibers (fast-twitch),

70
grow at a faster rate than type I fibers. The rate of muscle contraction in
Type II fibers is also of a greater rate, which suggests that they possess a
higher strength and power potential than type I fibers. This is significant to
the present study as individuals differ in fiber type for different muscle
groups. This could explain the significant increase in leg press strength
could simply be response-specific to each individual. Future research could
focus more on individual responses due to these differences.
The present study used the Concept2 Dyno Dynamometer to test 1RM
strength and did not simulate actual exercise movements. The most
commonly used exercises for upper and lower body muscular strength
testing are the traditional bench press and leg press, respectively. This may
have had an impact on the results and may not define true strength
because of not simulating actual exercise movements and exercise
conditions. Furthermore, The 1RM is the heaviest weight that can be lifted
in one attempt whilst maintaining proper form. This type of maximal
strength testing is considered the gold standard for evaluating dynamic
strength (ACSM, 2015). Form and heavy resistance were not factors, thus,
the present study did not entirely follow the exercise protocol of which is
considered ‘gold standard’ for strength testing.

71
ZMA is marketed as a ‘natural testosterone booster’, thus, highlighting the
importance of its hormonal effect. Hormone testing is concurrent in
previous literature for ZMA, along with strength testing. As there was no
testing for hormone status in the present study, it is inconsistent with
other literature. Hormone testing may have provided further analysis of the
results and the interaction effect of the supplement. It may have expanded
on current ideas and literature on explaining the significant effects and
how hormone levels may have elicited these,
Individual responses and a broader range of results for both ZMA and
placebo supplements may have been analysed had the present study used
a crossover design.
6.0 Conclusion
Despite the present study there has been very limited research on the
anabolic effects of ZMA, and no research on the recovery properties of the
supplement as a complete formulation. The anabolic effects of the
supplement remain equivocal, as there is a dissimilarity of results, including
that of the present study. The present study however, looks at the recovery
properties of the supplement and found positive responses, which leaves
for open interpretation in comparison to past literature and that of the

72
future. Additionally, although a significant effect was observed for 1RM leg
press strength, this does not substantiate the anabolic effects of ZMA as
no significant effect was observed for two out of the three exercises,
however, literature would suggest that ZMA Supplementation coupled with
resistance training may increase the secretion of anabolic hormones and
reduce the cellular damage. Furthermore, these results would indicate
biological factors peripheral to ZMA may have attributed to the causality
of the outcomes. The results of the recovery protocol would suggest that
ZMA’s recovery properties has some substance, although further research
is required to accredit or negate these findings. Future research should
look at the effects of recovery, hormone status, muscle size and strength
to get a complete overview and analysis, and to have consistency in-
comparison to the previous literature. Individual controls such as dietary
intake and training programs should also be controlled, as mechanisms
peripheral to the supplement can have causality in the outcome.
Additionally, a crossover design should be implemented, as it would
validate any correlated significant effects, as well as determine a washout
period (Chumney and Simpson, 2006). Furthermore, future research should
compare the effects of ZMA against Mn and Zn as synergists in order to
evaluate whether the ZMA supplement as a complete formulation is an
essential in sport and exercise.

74
APPENDICES
Appendix A - Participant information sheet
PARTICIPANT INFORMATION SHEET
WELKIN HUMAN PERFORMANCE LABORATORIES SCHOOL OF
SPORT AND SERVICE MANAGEMENT
The Effects of Chronic Zinc Magnesium
Aspartate (ZMA) Supplementation on Strength
& Acute Recovery In Recreational Male
Resistance Athletes
LOCATION OF PROJECT: (ON-SITE)
Welkin Laboratories
Eastbourne
BN20 7SP
INVESTIGATORS:
Arsalan Javaid:
Telephone contact: +44 (0)7702583568
Email: ajqueries@gmail.com

75
Gary Brickley:
Telephone contact: +44 (0)1273 643760
Email: G.Brickley@brighton.ac.uk
The participation information sheet provides an explanation and insight into why the
experiment is being conducted and the experimental procedures involved. Potential
risks and side effects may occur during the time of the study and participants will be
informed and made aware of the possible implications. Confidentiality and the
private information of the candidates for this study will be explained. After reading
the participation information sheet, please make a conscious decision of your
participation (withdrawal from the study is permissible at any time without any
implications of ramifications). If you need further assistance, please consider seeking
advice from a family member, friend or relevant professional.
BACKGROUND - EXPLANATION OF THE RESEARCH PROJECT
Athletes are constantly striving to break plateaus and optimise performances using
nutritional interventions and ergogenic aids. Doping and the use of anabolic steroids
is a trend amongst competitive bodybuilders and power lifters (Haff and Travis,
2015), although there are competitors who seek ergogenic aids through natural and
legal means. ZMA is a supplement marketed as having anabolic properties,
primarily, boosting testosterone and recovery combining the synergistic effects of
Zinc Monomethionine Aspartate, Magnesium Aspartate and Vitamin B6 (Villepigue
and Rivera, 2012). Strength will be assessed through 1RM testing on three exercises
(chest press, seated row and leg press), using the Concept-2 dynamometer strength
rig.
This study will consist of three visits to the labs; familiarisation and baseline testing
(pre) and post-supplementation testing. Testing will involve performing maximal
tests on three exercises on the Concept-2 Dyno Dynamometer. Appropriate
familiarization, demonstration and guidance will be given beforehand. 3 capsules of
ZMA are to be ingested the night before.
PARTICIPANT INCLUSION CRITERIA
Volunteers will:
1) Male resistance athletes aged 18 – 30 years.
2) Minimum of 1 year experience of resistance training
3) Be injury free and healthy
4) Resistance train at a minimum of 3 times per week
5) Refrain from strenuous exercise 48 hours prior to any testing
6) Have no personal history of cardiovascular or neurological disease

76
7) Refrain from alcohol consumption 48 hours prior to any testing.
8) Refrain from consuming caffeine 24 hours prior to any testing.
9) Have a body mass index (BMI) less than 30 kg/m2 i.e.: not classified obese.
10) Not currently be taking any anabolic steroids, and/or any other performance
enhancing drugs
11) Not currently be taking any ergogenic aids containing creatine, glutamine,
arginine, HMB, androstendione, thermogenics, or any other ergogenic
supplement at the time of study (or in the last 6 months).
WHAT WILL MY PARTICIPATION INVOLVE?
Laboratory Testing
Visit 1 – Familiarisation session.
The familiarisation session is in place to provide you with an overview of the whole
experimental procedure, and allow you to experience and attain familiarisation for the
techniques that will be used in each lab visit for testing. Demonstrations will be shown
and will have a practical opportunity to try the testing apparatus. You will also have
another opportunity to read through the participant information sheet and will be
required to complete a medical screening questionnaire and consent form. You will be
free to ask any questions during the familiarisation session.
Visit 2 – Baseline testing (pre)
Participants will perform maximal tests on three exercises (chest press, diverging row and
leg press) using the Concept-2-Dyno Dynamometer strength. Participants will have
already attained familiarisation from the previous lab visit, but can ask for a ‘practice’ set
if necessary. Participants will perform 3 reps on each exercise (See schematic below.)
- 1 repetition at 25% of 1RM
Each participant’s final and maximal effort of each set (100% of 1RM) will display a
number represented in kilograms (kg), which will be your score. This will be recorded.
Participants will rest for 5 minutes seated in between exercises. You are required to fill in
a 3-day sleep diary after this visit and before the supplementation period.

77
28-day supplementation period
During this period participants will consume 3 capsules of ZMA orally, on a nightly basis.
The supplement is to be ingested 60 minutes prior to sleep on an empty stomach, failure
to do so will void your participation from the study.
Visit 3 – Post-supplementation testing
Post supplementation testing will be no different to baseline testing. You will be required
to return any supplement dispensaries and/or unused supplements. You will be asked to
complete and return your 3-day sleep diary three days after testing.
IS THERE ANYTHING I NEED TO DO BEFORE COMING TO THE LABORATORY?
Recording your sleep: You will be asked to record the number of hours you slept, the
times you woke up during the night and the overall quality of your sleep for 3 days
after preliminary testing and 3 days after supplement load. You will be provided a 3-
day sleep diary form.
Controlling physical activity: This is crucial to the success of the study. Whilst we do
not ask you to refrain from physical activity, it is required for you to not take part in
any strenuous or demanding exercise 48 hours prior to testing.
Travelling to the laboratory: If you live locally, you can walk at a slow pace to the
laboratory for testing, but please DO NOT run or cycle as this may intervene with
research results. If you close by, it would be advised that you drive or catch public
transport to Welkin laboratory. If this is not possible then please let us know, and we
will arrange for your transport.
IS THERE ANYTHING I NEED TO BRING WITH ME?
Clothing: You will need to bring appropriate clothing for exercise i.e.: shorts, t-shirt
or vest, socks and trainers. The laboratories are climate controlled to 19 (°C)
Hydration: Ensure you are hydrated before each visit of testing to avoid
dehydration. You will be allowed to drink water during testing. We can provide you
with water.
Showers/Changing rooms: The laboratories are equipped with shower facilities, so
feel free to bring towels and a fresh pair of clothes for after the session.
ONCE I HAVE SIGNED UP FOR THIS STUDY, CAN I CHANGE MY MIND?
Withdrawal is permitted at any given time. After reading the information sheet and
asking any questions you may have regarding the study, you will be asked to sign an
informed consent sheet. Please be aware that the signing of these forms is not
legally binding and you are allowed to withdraw your participation from the study at
any given time, with no explanation and no implications.

78
WILL MY DATA BE KEPT CONFIDENTIAL?
Your information will be stored on computer; you will be provided with and referred
to as a number, in order to keep your personal information private and confidential,
in accordance with the Data Protection Acts of 1984 and 1998. Data will be used for
research purposes only and confidentiality will be maintained in any publications
arising from the study. Participants are able to access their own individual data upon
request. Data will not be kept longer than is necessary for the purposes of this
investigation and will be erased as applicable.
WHAT DO I GET FOR PARTICIPATING?
The study will provide you with Laboratory experience and an insight of how the
sport and exercise science world works. You will also be gain an insight of your 1RM
performance on 3 different exercises and your recovery, and how this is affected by
a 28-day supplementation period. After the study we will provide you with feedback
regarding your own results.
ARE THERE ANY RISKS AND/OR DISCOMFORT?
Maximal testing may cause breathlessness, dizziness and some discomfort. However,
due to the short period of testing, participants are not expected to experience any of
these. Resistance athletes with a minimum of one years experience should not have
any problems with the exercise protocol; however, safety measures will still be
implemented. Muscoskeletal injuries may occur during the time of the study,
however, risks are minimal and measures will be implemented to prevent any
occurrences. Guidance and demonstrations on the correct posture, technique and
execution will be given to eliminate risk of injury. Each candidate for this study will
be supervised carefully and accordingly.
REMINDER: THIS STUDY IS RELIANT ON VOLUNTEERS, HOWEVER IF AT ANYTIME
THROUGHOUT THROUGH OUT THE STUDY YOU WISH TO WITHDRAW YOUR
PARTICIPATION THEN YOU ARE FREE TO DO SO WITHOUT EXPLANATION AT ANY
TIME WITHOUT ANY RAMAFICATIONS.
CONTACTS
Please feel free to ask any questions, at any stage. Contact details for the staff
involved in the study are as follows:
Arsalan Javaid:
Telephone contact: +44 (0)7702583568

79
Email: ajqueries@gmail.com
Gary Brickley:
Telephone contact: +44 (0)1273 643760
Email: G.Brickley@brighton.ac.uk
Appendix B - Informed Consent
INFORMED CONSENT FORM
WELKIN HUMAN PERFORMANCE LABORATORIES SCHOOL OF SPORT
AND SERVICE MANAGEMENT
The Effects of Chronic Zinc Magnesium Aspartate (ZMA)
Supplementation on Strength & Acute Recovery In Recreational Male
Resistance Athletes
The purpose and details of the above study have been explained to me and I
understand that this study is designed for the primary reason of furthering scientific
research and knowledge. All procedures involved have been approved by the
University of Brighton Ethical Advisory Committee.
 I have read and understood all information contained in the participant
information sheet and this consent form.
 I have had the opportunity to ask any questions about my participation in this
study.
 I understand I am under no obligation to volunteer in the study.
 I understand I have the right to withdraw from thre study at any stage
without giving any reason and/or explanation.
 I understand that all information I provide will be dealt with in a strict
confidential manner.
 I agree to participate in this study and am aware of all procedures that will
take place and I have been informed of risks associated to these activities.
 I agree for my information to be kept on an evidence file that will be kept on
a secure computer with no other use or distribution.
Name:

80
Your signature:
Signature of investigator:
Date:

81
Appendix C – Medical Questionairre (Part A)

82
Appendix D– Medical Questionairre (Part B)

83
Appendix E – Risk Assessment Forms

86
COSHH RISK ASSESSMENT FORM
For single substances
Activity and hazard properties
College: University of Brighton School/Department: Sport and Ex.
Science
Location of activity: Hillbrow Sports Centre
Description of activity: Subjects will ingest 3 ZMA capsules on an empty stomach
the night before testing [Wilborn et al., 2004].
Substance name Zinc Monomethionine/Magnesium Aspartate
[ZMA]
CAS Number
Quantity used
(grams/litres)
Serving Size = 3 Capsules
Zinc: 30 mg
Magnesium: 450 mg
Vitamin B6: 10.5 mg
Intake referenced from Effects of Zinc Magnesium
Aspartate (ZMA) Supplementation on Training
Adaptations and Markers of Anabolism and
Catabolism [Wilborn et al., 2004]
Workplace exposure limit
Harmfu
l/
irritant
Flammabl
e/ highly
flammable
Dangerou
s to the
environme
nt
Corrosiv
e
Health
hazard
Oxidise
r
Toxic/
very
toxic
Explosiv
e
Please attach MSDS for the substance to the hard copy of this sheet
Can this product be substituted
with a less hazardous ones? Yes  No
If yes give reason for not doing so:
Is the substance being decanted
from a larger container? Yes  No

87
If yes what size is that container?
How is the substance used?
(e.g. diluted, applied,
dissolved)
Swallowed as capsule.
Persons at
risk
Staff Students Visitors Contractors Public
How often is
the
substance
used?
Multiple
times daily
Daily Weekly Monthly Rarely
3 capsules
on a daily
basis.
How long are people exposed to
the
substance when used?(mins)
The supplement will take 1.5 hours to digest after
consumption.
When is the
substance
hazardous?
In contact
with eyes
In contact
with skin
Inhaled Ingested Injected
May
cause
choking
when
swallowe
d as
capsule.
What is the level of
risk posed by
exposure
Low Medium High
Control measures
General precautions Instructions will be in place to ensure the safety
of the particpants.
Engineering controls
Training/briefing requirements The participants are required to consume the
capsules on a nightly basis.
Do the control measures reduce the
risk to an acceptable level? If recommended isntructions are followed
accordingly, risk is reduced signficantly.
Are there any further control
measures required?
Required PPE

88
Other: Other:
Hygienic
Type:
Wear
general work
gloves to
minimize
skin contact.
Type:
Goggles
or safety
glasses.
Type: Type: Type:
General
(mechani
cal) room
ventilatio
n
satisfacto
ry
Type: Type: Type: Wash
thoroughly with
soap and water
after handling
product.
First aid procedure
Area exposed Risk to health First aid procedure
Skin Exposure to liquid or
mists may cause minor
irritation
Wash contacted skin areas with
soap and water. Change soaked
clothing.
Eyes Direct contact may
cause temporary
discomfort with redness
and dryness.
Wash eyes thoroughly with
water for a minimum of 15
minutes. If irritation occurs, call
a physician.
Inhalation May be irritating to nose,
mouth, throat and lungs.
If irritation occurs remove to
fresh air.
Ingestion May cause nausea,
vomiting, diarrhea and
abdominal pain.
Drink several glasses of water
Do not induce vomiting. Consult
a physician.

89
Waste and spillage procedures
Storage requirements MUST be kept in a cool dry place out of
direct sunlight
Spillage procedure
Contain spill and sweep up. Not a hazard if
uncontaminated.
Ecological controls
Disposal procedure
Dispose of in accordance with applicable
Federal, State and Local regulations.
Fire controls
Water Powder Foam CO2
Wet
Chemical
Additional comments
Any side effects or accidental misuse of the supplement will require immediate
professional health care.
Assessor: Arsalan Javaid Date completed:
Manager’s
signature:
Gary Brickley
Date:
Review date:

90
COSHH RISK ASSESSMENT FORM
For single substances
Activity and hazard properties
College: University of Brighton School/Department: Sport and Ex. Science
Location of activity: Hillbrow Sports Centre
Description of activity: Subjects will ingest 3 Maltodextrin capsules on an empty
stomach the night before testing [Wilborn et al., 2004].
Substance name Maltodextrin
CAS Number
Quantity used
(grams/litres)
Workplace exposure limit
Harmful/
irritant
Flammable/
highly
flammable
Dangerous
to the
environme
nt
Corrosive Health
hazard
Oxidiser Toxic/
very
toxic
Explosive
Maltodextrin
becomes a
flammable
dust when
finely divided
and suspended
in air. Keep
product away
from sources
of ignition,
sparks and
open flames.
Provide
adequate dust
control and
ventilation.
Exposure to
extreme heat
builds up
pressure in
closed

91
containers.
Cool with
water stream.
Please attach MSDS for the substance to the hard copy of this sheet
Can this product be substituted
with a less hazardous ones? Yes  No
If yes give reason for not doing so:
Is the substance being decanted
from a larger container? Yes  No
If yes what size is that container?
How is the substance used?
(e.g. diluted, applied, dissolved)
Swallowed as capsule.
Persons at
risk
Staff Students Visitors Contractors Public
How often is
the
substance
used?
Multiple times
daily
Daily Weekly Monthly Rarely
3 capsules
on a daily
basis.
How long are people exposed to the
substance when used?(mins)
The supplement will take 1.5 hours to digest after
consumption.
When is the
substance
hazardous?
In contact
with eyes
In contact
with skin
Inhaled Ingested Injected
May
cause
choking
when
swallowe
d as
capsule.
What is the level of risk
posed by exposure
Low Medium High
Control measures
General precautions Instructions will be in place to ensure the safety of
the particpants.
Engineering controls
Training/briefing requirements The participants are required to consume the

92
capsules on a nightly basis.
Do the control measures reduce the
risk to an acceptable level? If recommended isntructions are followed
accordingly, risk is reduced signficantly.
Are there any further control measures
required?
Required PPE
Other: Other:
Hygienic
Type: Wear
general work
gloves to
minimize skin
contact.
Type:
Goggles
or safety
glasses.
Type: Type: Type:
General
(mechanic
al) room
ventilatio
n
satisfactor
y
Type: Type: Type: Wash
thoroughly with
soap and water after
handling product.
First aid procedure
Area exposed Risk to health First aid procedure
Skin Exposure to liquid or mists
may cause minor irritation
Wash contacted skin areas with
soap and water. Change soaked
clothing.
Eyes Direct contact may cause
temporary discomfort with
redness and dryness.
Wash eyes thoroughly with water
for a minimum of 15 minutes. If
irritation occurs, call a physician.
Inhalation May be irritating to nose,
mouth, throat and lungs.
If irritation occurs remove to fresh
air.
Ingestion May cause nausea,
vomiting, diarrhea and
abdominal pain.
Drink several glasses of water Do
not induce vomiting. Consult a
physician.

93
Waste and spillage procedures
Storage requirements MUST be kept in a cool dry place out of direct
sunlight
Spillage procedure
Contain spill and sweep up. Not a hazard if
uncontaminated.
Ecological controls
Disposal procedure
Dispose of in accordance with applicable
Federal, State and Local regulations.
Fire controls
Water Powder Foam CO2 Wet Chemical
Additional comments
Any side effects or accidental misuse of the supplement will require immediate
professional health care.
Assessor: Arsalan Javaid Date completed:
Manager’s
signature: Gary Brickley
Date:
Review date:

94
Appendix G – Sleep Diary
Participant Number: (This is the number you were provided)
As a participant, it is necessary for you to fill in this sleep diary 3-days after
preliminary testing and 3 days immediately after supplement testing, as
informed.
You will need to bring this in after completing the first phase (Before supplement
testing), failure to do this may result in your exclusion of the study. PLEASE keep
this safe, as you are required to return this once completed.
Hours Slept – The approximate amount of hours you slept.
Awakenings – The approximate amount of times you awoke during the night.
Quality of Sleep - 1 being the poorest quality (of sleep) and 10 being the greatest.
Before Supplement Testing:
Hours Slept Awakenings Quality of Sleep
(1-10)
Day 1
Day 2
Day 3
After Supplement Testing:
Hours Slept Awakenings Quality of Sleep
(1-10)
Day 1
Day 2

95
Day 3
Appendix G – Pilot Testing
Pilot Testing Of Concept-2 Dyno Dynamometer Strength Rig
The pilot testing consisted of performing 10 x 1 Rep Max repetitions on
the Concept 2 Dyno dynamometer. For each of the three exercises: chest
press, diverging row and leg press. Each exercise was performed ten times
to give ten 1RM scores (kg) for a participant.
Exercise Protocol:
 Attained correct posture/position for each exercise.
 1 repetition at 25% (Of perceived maximal effort)
 A 5 minute rest after each 1RM (Static rest)

96
Standard deviation of repeated trials:
The Standard Deviation (SD) of repeated trials may be applied to several
trials in one testing session and are used to prove consistency and
dependability of measures.
Results:

97
Table 1. Reproducibility: standard deviation of repeated 1RM tests for each exercise. All
1RM tests on each exercise were tested on the same day. The 1RM variation was
expressed as the standard deviation (SD) of the mean of each of the 10 test results for
each exercise. The coefficient of variation for each exercise was calculated by the sum
SD/MEAN x 100.
Results:
As displayed in table 1 the coefficient variation for chest press = 0.76;
diverging row = 0.69; leg press = 0.33. The coefficient variation is a
statistic used to display variability of distribution when looking at data
(Hanneman, Kposowa and Riddle, 2013). Distributions with coefficient
variation of less than 1 are considered low-variance (Erlang distribution),
representing very low variability in 1RM scores across 10 attempts (Ghatak,
2010). This is evidence to validate and support the means of testing using
the Concept-2 Dyno Dynamometer as an accurate means of testing with
low variance across 1RM strength testing. These findings are in accordance
to the test-retest reliability of Bampouras et al. (2014) for the Concept-2
Dyno Dynamometer (Bampouras et al., 2014)

98
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