Resistance exercise

Definitions:
 Resisted exercise:
Resisted exercise is any form of active exercise in which
dynamic or static muscle contraction is resisted by an
outside force applied manually or mechanically.

 Strength: Muscle strength is the greatest measurable
force that can be exerted by a muscle or muscle group
to overcome resistance during a single maximum
effort.
 Power: Muscle power is defined as work produced by
the muscle per unit of time. Power=
forceXdistance/time
 Endurance: It is the ability to perform low intensity
repetitive or sustained activities over a prolonged
period of time.

Types of muscle works:
 Isometric muscle work:
in this type of muscle work there is increase in tone of
the muscle without any change in the muscle length.
e.g. isometric strengthening for neck extensors: the
clasped hand behind the head is pushed back by the
head. No movement of the head or neck occurs but the
tone of neck extensors increases.

 Isotonic muscle work: in this type of muscle work there is
change in length of the muscle while it maintains an even
tone throughout the contraction period. This is of two
types
 Concentric work: here the origin and insertions come
closer and the muscle length shortens.
 e.g getting up from a chair: knee and hip extensors
contract concentrically to bring about extension in these
two joints.
 Eccentric work: here the origin and the insertion go away
from each other and the muscle length increases.
 e.g. sitting on a chair from standing: : knee and hip
extensors contract eccentrically to bring about flexion in
these two joints.

 In concentric contraction the force generated by the
muscle is greater than the resistance.
 In isometric contraction force generated by the muscle
is equal to the resistance.
 In eccentric contraction the force generated by the
muscle is lesser than the resistance.

Principles resistance exercise
 Principle of overload:
 If muscle performance is to improve , a load that
exceed the metabolic capacity of the muscle must be
applied; that is a muscle must be challenged to
perform at a level greater than to which it is
accustomed.
 Overload can be applied by increasing the intensity or
volume. In strength training the intensity is increased
where as in endurance training the volume i.e.
frequency, repetitions and time is increased.

 SAID (Specific Adaptation to Imposed Demand )
principle:
 Adaptations produced by the training are highly
specific to the nature of the stimulus or overload
applied.
 SAID applies to all the systems of the body.
 The adaptations are specific to strength, power,
endurance, functional activity, joint angle, sequence of
muscle activations, energy systems and virtually all
other variable present.

 Principle of Reversibility:
 The adaptations achieved through resistance exercise
persist as long as the resistance exercise is performed
regularly and go back gradually to the pre exercise
levels once the training is stopped. This means the
effects of resistance training are reversible.

 Inter individual variability:
 Every individual responds to resistance exercise in a
different way, thus similar stimuli may bring about a
lot of improvement in one patient and no
improvement in others.

Ranges of muscle work
FULL RANGE:
Contraction takes place
throughout the range, starting
from fully stretched position
in case of concentric
contraction and from fully
shortened position in case of
eccentric contraction.
Full range contractions are
normally needed only during
emergencies (e.g. preventing a
fall).
Uses:
Maintain joint mobility
Increase circulation
Preparation for situations when
power & mobility is needed.

INNER RANGE:
The muscle either shortens
concentrically from half
way of its range, or is
lengthened by eccentric
contraction from fully
contracted state to halfway.
Uses:
Gain or maintain joint
movement in the direction
of muscle pull.
Train some extensors that
stabilize joints. E.g. Knee:
VMO strengthening

 OUTER RANGE:
Concentric contraction from
fully stretched position to
halfway range and eccentric
contraction from halfway
range to the fully contracted
position
Uses:
Very useful for initiation of
contraction (stretch reflex
acts better)
Muscles contract more
forcefully (Frank sterling law)

MIDDLE RANGE:

In this range of muscle work
the muscles neither reach
the fully contracted range
nor are fully stretched, but
moves only in the range
inbetween. This range is
most functional and
generally most efficient
(angle of pull near 90
degree)
USES:
Maintenance of muscle tone
and normal power .

Group action of muscles

1. Prime movers/ agonists
2. Antagonists
3. Synergists
4. fixators

Prime movers
 They are the muscles who bring about the movement
by contraction. They are responsible for most of the
e
forces generated in the movement.
 E.g. for shoulder abduction deltoid is acting as the
prime mover.

Antagonists
 These are the muscles that are opposing group of
prime movers. They relax and are lengthened (either
passively or eccentrically) to allow controlled
movement.
 E.g. shoulder adductors lengthen passively during
abduction, knee extensors lengthen eccentrically
during knee flexion in standing to sitting

Synergists
 They work or relax to modify the movement of the
prime movers. They may alter the direction of pull of
prime mover or when a multijoint muscle is the prime
mover, fix the joint where movement is not required in
a position of advantage.
 E.g. rotator cuff in shoulder alters the pull of deltoid
and creates abduction. Without them the deltoid
would create an upward translation.
 While making a fist the finger flexors are
agonists, they are multijoint muscle and can flex the
wrist too. The wrist extensors act as synergist and fix
the wrist in extension so that the force of prime
movers are used only in fingers.

Indications
1. Curative:
 Muscle: weakness or paralysis
 Bone: to increase density
 Aerobic system: improves aerobic capacity
 Other connective tissues: improve pliability and strength

2. Preventive:
 to preserve muscle power in all the conditions where muscle weakness
is anticipated.
 To live a healthy life with high levels of fitness.
3. Preparative: to prepare for some specific activity where the adaptations
of resistance exercise will be useful, e.g training for arm muscles of a
boxer will prepare him for a better performance.
4. Recreative: various form of resistance training is used as sports and
recreation activity, like body building.

Causes of muscle weakness &
paralysis
I. Lesions in motor pathway:
A. Lesion in brain / spinal cord: spastic paralysis e.g
stroke, spinal cord injury
B. Lesions in AHC: flaccid paralysis: e.g polio
C. Lesion in peripheral nerve: flacccid paralysis, e.g.
Saturday night palsy
II. Lesion affecting muscle tissue:
A. Degeneration, e.g. muscular dystrophy
B. Ischemia e.g. VIC
C. Scarring e.g. cut injuries

Causes of muscle weakness &
paralysis
III. Disuse of normal nerve and muscle: can occur
because:
A. Muscle inhibition by pain or spasm
B. Rest:Splintage, immobilisation or bed rest
C. Hypoactive patient
IV. Other causes:
A. Systemic illness: constitutional diseases like RA
causes marked muscle wasting
B. Functional: apparent muscle weakness for secondary
gain.

Adaptations of resistance exercise
I.Neural adaptation:
Starts within 4 weeks of regular training.
Caused by decreased CNS inhibition, decreased GTO
sensitivity & changes in NMJ
 Increased no. of motor unit recruitment
 Increased rate of firing
 Synchronized firing

II. Skeletal muscle adaptation:

A. HYPERTROPHY
It is increase in the muscle bulk without increase in the no
of muscle fibers, due to increased myofibril volume.
Starts between 4-8 weeks of resistance training.
Caused by increased protein synthesis and reduced protein
degradation.
Maximum hypertrophy in high volume moderate resistance
exercises performed eccentrically.


B. HYPERPLASIA
It means increase in the no of muscle fibers.
A small portion of muscle fibers may increase in no by
longitudinal splitting.
C. VASCULAR & METABOLIC ADAPTATIONS
Decreased capillary bed density
Decreased mitochondrial density
ATP & CP storage increase
Myoglobin storage increases
CPK & Myokinease increase

III. Bone:
Minimizes or prevents loss of bone mineral density.
Can be used for the treatment of osteoporosis/
osteopenia
IV. Connective tissue
Tensile strength of tendons ligaments and connective
tissue in muscle increses

DETERMINANTS OF RESISTANCE TRAINING
1. Frequency
2. Intensity
3. Time
4. Type
5. Alignment & Stabilization
6. Volume
7. periodization
8. Rest interval
9. Sequencing
10. Integration to functional activities
(FITT pas vir)
The determinants are interdependent for a successful
regime

frequency
 No. of exercise sessions per day or per week.
 Depends on the goal or adaptaion desired, should be
set in accordance with intensity and volume.
 Importance:
Decides the rest time between two sessions of exercise.
The rest is needed to recover from the fatigue and for
the adaptations (e.g. protein sysntesis) to occur.
Higher the intensity and volume lower should be the
frequency, as strong exercises creates microtrauma
which needs time to recover.
In immediate post surgery conditions short sessions of
exercise is given several times a day whereas high
intensity exercise for body building are usually
performed 3-5 sessions a week.

Frequency contd.
 Excessive frequency: progressive fatigue, decline in
performance, overuse injury
 Inadequate frequency: no or minimal adaptaions

Intensity/ exercise load/ training load
The intensity is the amount of resistance/ load imposed on
the contracting muscles during each repetitions of an
exercise.
2 types:
Maximal
maximal intensity resistance of a muscle is the highest
resistance a muscle can withstand, higher than maximal
intensity being beyond the muscle’s capacity
Submaximal
submaximal intensity resistance is a resistance that is lower
than the maximal intensity, usually some percent of the
maximal intensity (between 30 to 80%)

Repetition maximum
RM is a method of quantifying exercise intensity, Givenn
by Delorme
Definition:
A repetition maximum is defined as the greatest amount
of weight a muscle can move through the available
ROM a specific no of times.
1 RM for a muscle is the maximum weight (resistance)
with which the muscle can contract through full/
available ROM for one time. The muscle will be unable
to perform the repetition for a second time .
10 RM for a muscle is the maximum weight (resistance)
with which the muscle can contract through full/
available ROM for 10 times. The muscle will be unable to
perform an 11th repetition .

Uses of RM
1. To document a baseline measurement of dynamic
strength of a muscle
2. To identify an exercise load to be used during
exercise
3. To find out prognosis in reassessment and alter the
exercise regime accordingly.

How to measure 1RM
Measured by repetitions to fatigue method using
equations/ charts.
Various equations and charts are available eg.
1 RM=(No of reps/30+1)X weight used
Example: if one lifts 15 kg for 20 times, 1RM= ?
For reps to fatigue the muscle is warmed up and
stretched and then given a weight (preferrably free
weight) which can be performed comfortably over 5
repetitions. The no of repetition the candidate can
perform before fatigue is noted.

Training zone
The amount of resistance to be used in a training
program is usually a percentage of 1RM
For sedentary: 30-40% of 1 RM
For untrained healthy individual: 60-70% of 1 RM
For highly trained: 80-95% of 1 RM

Time/duratiion
The duration of a resistance training regime is the total
no of weeks or months during which the exercise
program is carried out.
Duration determines the adaptations:
<4 weeks program-neural adaptation only.

6-12 weeks program- musculoskeletal adaptation
(hypertrophy, increased vascularization)

Alignment and stabilization
Alignment and stabilization is necessary for isolation of
muscle and to prevent substitution.
Stabilization can be external or internal by isometric
contraction of a fixator, (e.g. abdominals in case of
SLR)

volume
Volume is the summation of the total no of repetitions
and sets of a particular exercise during a single exercise
session multiplied by the resistance used.
Higher the intensity lower the no. of repetitions.
Repetitions
Repetitions is a no of times a particular movt is repeated
in a series of complete and continuous excursions
against a specific load.
Set
A predetermined no of repetitions grouped together is
known as a set or bout. After each set there is a brief
interval of rest.

 Determination of repetitions:
It is based on the principle of repetition maximum.
Most commonly 10 repetitions of 10 RM is used. 10 RM is
approximately 75% of 1RM.
Alternatively 15 RM (60% of 1 RM) or 5 RM (90% of 1
RM) is used.
A session may have a single set or multiple sets.
Single set exercises are used with low intensity in early
phases of rehab. For strength gaining multiple sets are
recommended.
For strength gain: low repetitions high resistance
For endurance gain: high repetitions low resistance

Rest interval
Rest between the sets in a session and between two sessions.
It allows the muscles to overcome the acute effects of exercise
related to fatigue.
Depends on the intensity and volume of the exercise. Higher
the intensity longer the rest interval. Also phasic muscles
need longer rest than tonic muscles.
Moderate intensity: 2-3 min rest between sets
High intensity: 4-5 min.
While one group is resting opposite group can be exercised.
Active recovery which involves exercising without resistance
between the sets is more efficient than passive recovery.
For rehabilitative purposes and heavy exercise 48 hrs between
the sessions gap is needed.

periodization
Systematic variation of intensity and volume of exercise
at regular intervals over a specific period of time.
It’s purpose is to optimize training and performance
during the time of competition in a calendar.
Most useful for competition athlete, less useful for rehab
purposes.
Parts:
Preparation phase, competition phase (peaking) &
recuperation phase.

sequencing
 Exercise order:
When multiple muscle groups are exercised in a
session, large groups to be exercised before
small, multijoint muscles to be exercised before single
joint muscles, higher intensity exercise to be
performed before lower intensity exercise.

Types of resistance
 Manual and mechanical
 Static and dynamic
 Concentric and eccentric
 Open and closed chain
 Constant and variable load
 Isokinetic exercise.

Manual and mechanical resistance
 Manual resistance:
 Resistance is provided by hand.
Can be provided by a therapist or self resisted.
Can not quantify resistance
Useful for weak muscles in the early stages of rehab or
conditions which needs careful control.
 Mechanical resistance:
 Resistance is applied through the use of equipment or
mechanical apparatus.
Amount of resistance can be measured and can be
increased progressively.
Useful when strong exercises needed.

Types of mechanical resistance
 1. weights
Sandbags/ metal weights/ medicine bags etc are used. The
weights are either held in hand or secured to the bodypart by
some comfortable means like straps.
advantage:
Less equipment- convenient for home
Resistance can be measured and altered easily
Easy to understand and perform
Disadvantage:
Resistance always works vertically, in the direction of gravity. It
is difficult to position some muscles for adequate resistance

2. Weight and pulley circuit.
It uses weights and a no of pulleys with a rope.
Advantage:
The pulleys change direction of pull and thus the direction of
resistance is not only limited to vertical, like free weights.
Disadvantage:
Costly, space occupying machines needed.
3. elastic resistive devices.
Various substances of elastic nature, e.g. spring, theraband
and theratubes are used with increasing popularity.
Advantage:
Calibrated resistance, often with colour codes.
Direction not limited as in gravity dependent resistances
Handy, easy to carry

Disadvantage:
variation of resistance is difficult, needs change of
equipment.
4. Malleable resistance:
Putty, clay, wax, plasticines etc.

5. water:

Static and dynamic exercise
Static exercise: indications
1. To prevent atrophy when joint movt. Is not possible
2. To activate muscles without disturbing healing tissues
3. To develop postural/ joint stability
4. To develop isometric muscle strength
5. To improve muscle strength when dynamic
strengthening is painful

Types of static exercise
1. Setting exercise:
Low intensity isometric with very low or no resistance.
Decreases pain and spasm and promotes relaxation and
circulation
2. stabilization:
Sustained submaximal co contraction in weight bearing /
antigravitynposition.
3. Multiple angle isometrics:
when joint motion is permissible but dynamic movt. Is not
advisable.

Dynamic resistance exercise:
This type of exercise allows movement with resistance.
Can be concentric or eccentric.

Open and closed kinematic chain
exercise

OKC:
In this type of exercise the distal end of the limb is not
fixed and movements of any joint can occur isolatedly
without the movement of other joints in the chain.
CKC:
In this type of exercise the distal end of the limb is fixed
and movements of any joint brings about movements
in the other joints of the chain.

Isokinetic exercise
 In this type of exercise the angular velocity of the
movement remains constant. This type of exercise
needs computer controlled equipment which matches
the resistance with patient’s effort.

PRE
Progressive resistance exercise is a dynamic resistance
training in which a constant external load is applied to
the contracting muscle by some mechanical means
and incrementally increased.
The RM is used as the basis of progression in the
resistance.
Multiple sets are used in a session, which may consist of
2-3 sets of 6-12repititions of 6-12 RM
Common variants are DeLorme, Oxford and McQueen
method.

Delorme: 4 sessions weekly, progress 10 RM once weekly
oxford:5 times weekly

 McQueen Regime:
10reps@ 100% of 10RM

3 sessions weekly. Progress 10 RM every 1-2 week

Guidelines to prescribe resistance exercise
1.Examination and evaluation
 Determine the baselines:
a. General physical examination
b. strength: MMT, Dynamometry, RM
c. ROM: Goniometry
d. Functional performance
 Decide if strengthening is needed and appropriate at
this point
 Periodic reassesment

2.Preparation
a. Plan the regime: FITT pas vir, decide according to the
need and equipment available
b. Explanation and demonstration
c. Appropriate clothing, surface, diet, hydration, tim
3. Application
a. Warm up: light repetitive, dynamic exercise for the
muscles to be exercised. Stretching.
b. Placement of resistance: distally
c. Direction: concentric=opposite to movt, eccentric=
towards
d. Stabilization: external/internal
e. cooldown

precaution
1. Valsalva
2. Substitiution
3. Overwork( weakness)/overtraining (fatigue)
4. Muscle soreness: acute and DOMS
5. Pathological fracture

contraindication
1. pain:
Pain in free active movement
Acute pain in resisted isometrics
Pain that can not be eliminated by reducing the
resistance
2. inflammation:
Acute inflammation in muscle or inflammatory neuro
muscular pathology
Dynamic exercise is contraindicated in inflammation of
the joint
3. Severe cardiopulmonary disease.
4. Loss of joint integrity

Resistance exercise

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Resistance exercise