A comparison of 2 circuit exercise training techniques

A Comparison of 2 Circuit Exercise Training Techniques
for Eliciting Matched Metabolic Responses in Persons
With Paraplegia
Mark S. Nash, PhD, Patrick L. Jacobs, PhD, Jeffrey M. Woods, MSPT, James E. Clark, BS,
Tanya A. Pray, MSPT, Alex E. Pumarejo, MSPT
ABSTRACT: Nash MS, Jacobs PL, Woods JM, Clark JE,
Pray TA, Pumarejo AE. A comparison of 2 circuit exercise
training techniques for eliciting matched metabolic responses
in persons with paraplegia. Arch Phys Med Rehabil 2002;83:
201-9.
Objective: To test whether acute metabolic (V˙ O2), chrono-
tropic (heart rate), and perceptual (rating of perceived exertion;
RPE) responses to exercise by persons with paraplegia differ
when the exercise is on a multistation isoinertial exercise
system (MultiGym) or on a customized system of Thera-
Band® resistance bands (ElasticGym).
Design: Within-subjects comparison of 2 treatments.
Setting: Academic medical center.
Participants: Sixteen men and 1 woman with complete
paraplegia (T4–L1), as defined by the American Spinal Injury
Association.
Interventions: A circuit resistance training (CRT) program
for persons with paraplegia was adapted to both a MultiGym
and a customized ElasticGym. Exercises used for training and
testing used 6 resistance maneuvers at 50% of the 1-repetition
maximum (1-RM), with interposed rapid arm spinning. Sub-
jects were habituated to both conditions for 2 weeks before
testing on randomized nonconsecutive days.
Main Outcome Measures: V˙ O2 (L/min) was measured by
portable spirometry, heart rate (beats/min) by a chest strap mon-
itor, and RPE by the Borg Scale of Perceived Exertion (6–20).
Results: No significant effects of test condition on average
V˙ O2 or heart rate were observed, with differences between
conditions reflecting only .08L/min and 6.4 beats/min, respec-
tively. Average RPE was significantly higher in testing under
the ElasticGym condition (P Ͻ .05).
Conclusions: CRT on a customized ElasticGym system
elicited acute metabolic and chronotropic responses that did not
differ from responses to exercise on a MultiGym, though RPE
was greater with the ElasticGym.
Key Words: Exercise; Paraplegia; Rehabilitation; Spinal
cord injuries.
© 2002 by the American Congress of Rehabilitation Medi-
cine and the American Academy of Physical Medicine and
Rehabilitation
EPIDEMIOLOGIC STUDIES conducted in the early 1980s
and thereafter reported that cardiovascular disease was the
major cause of death for persons with spinal cord injury
(SCI).1,2 It has since been reported that asymptomatic cardio-
vascular disease occurs at an earlier age in persons with para-
plegia than it is predicted to occur in persons without disabil-
ity.3,4 This increased susceptibility has been attributed in part to
the sedentary lifestyle that is common among people with
SCI.5,6 Despite having unrestricted use of their upper extrem-
ities, physical inactivity is so profound among persons with
paraplegia that reports place them near the lowest end of the
physical fitness spectrum.7-9 These observations are supported
by a study in which 25% of healthy young persons with
paraplegia had a peak oxygen consumption (VO2peak) during
upper-extremity work of less than 15mL ⅐ kgϪ1
⅐ minϪ1
—a
level only marginally sufficient to maintain independent liv-
ing.5 The cardiovascular disease risks for persons with para-
plegia from inactivity are likely increased by hyperinsulin-
emia10-12 and excessive body fat,13 which are also common
among persons aging with paraplegia14 and are often associated
with a sedentary lifestyle in people without physical disabil-
ity.15,16 No evidence suggests that the level of fitness in these
individuals will improve without exercise.
The benefits of upper-extremity exercise for persons with
paraplegia have been reported by many investigators,6,17-21 and
these studies usually observe that endurance exercises that use
arm and wheelchair ergometers improve the fitness levels of
persons with SCI. Unfortunately, most of these arm exercise
protocols fail to address the need for upper-extremity strength-
ening, and they use repetitive contractions of shoulder muscles
that may hasten pain and dysfunction of the upper extremi-
ties.22-26 Such exercise may therefore threaten function and
independence of persons aging with paraplegia. To address
these training limitations, other investigators have used resis-
tance exercises to condition the upper extremities, although
with mixed results.20,27,28 In some cases, these programs have
improved upper-extremity strength, although the combined
goals of improved endurance and global strengthening of the
shoulder complex were not achieved by any of these programs.
We have recently examined the conditioning effects of a
circuit resistance training (CRT) program for persons with
paraplegia.29 This conditioning program was modeled on a
previous study of CRT for adolescents with insulin-dependent
diabetes that reported both improved cardiorespiratory endur-
ance and muscle strength.30 Increased endurance, strength, and
cardiac pumping capacity of persons without disability have
also been reported after CRT,30,31 and were also observed as
training benefits in persons with paraplegia undergoing similar
exercise conditioning.29,32 To make this type of conditioning
more widely available to persons with physical disabilities
requires that the training modes for strength building and
endurance activities be moderately priced, widely available,
and occupy a limited amount of space. These are conditions
that most exercise equipment adapted for use by persons with
From the Departments of Orthopaedics & Rehabilitation (Physical Therapy) (Nash,
Woods, Clark, Pray, Pumarejo) and Neurological Surgery (Nash, Jacobs); and the
Miami Project to Cure Paralysis (Nash, Jacobs), University of Miami School of
Medicine, Miami, FL.
Accepted in revised form March 14, 2001.
Thera-Band® supplies for this study were provided by the Hygenic Corp.
A commercial party with a direct financial interest in the results of the research
supporting this article has conferred or will confer a financial benefit upon the author
or one or more of the authors.
Reprint requests to Mark S. Nash, PhD, Dept of Orthopaedics & Rehabilitation
(Div of Physical Therapy), 5915 Ponce de Leon Blvd, 5th Fl, Coral Gables, FL 33146,
e-mail: msnash@miami.edu.
0003-9993/02/8302-6548$35.00/0
doi:10.1053/apmr.2002.28011
201
Arch Phys Med Rehabil Vol 83, February 2002

SCI do not satisfy. We have thus redesigned this circuit to use
elastic bands (Thera-Band®a) for resistance and not to require
an arm ergometer for the endurance phases of exercise. This
study examined the safety of this system, and tested the hy-
pothesis that the acute metabolic, chronotropic, and perceptual
responses of subjects with paraplegia to exercise by using
elastic bands would match those obtained when exercises were
conducted on a commercially available, multistation isoinertial
exercise system.
METHODS
Participants
Our subjects were 17 healthy participants (16 men, 1
woman) between 20 and 45 years old with chronic neurologi-
cally stable SCI between the T4 and L1 levels for more than 1
year. Subjects were randomly recruited from a database search
of local candidates who matched the ages, levels, and durations
of SCI that we established for participation. The T4 level was
designated as the upper limit of SCI because persons with
lesions at or below this level experience both competent and
relatively similar cardiovascular responses to exercise.32,33
Three subjects withdrew or were excused from the trial before
its completion (1 because of musculoskeletal complaints after
starting the trial, 1 for failure to attend training sessions, 1 for
personal reasons unrelated to the study).
All subjects had neurologically complete spinal cord lesions
as defined by the American Spinal Injury Association Stan-
dards for Neurological Classification.34 Subjects included those
in good health (defined as asymptomatic for acute treatable
illness) and without histories of shoulder joint dysfunction
(defined as chronic pain that limited range, or subluxation at
rest or during activity). The absence of cardiac arrhythmia or
ischemia at rest and during exercise stress was assessed by a
peak effort graded exercise test with 12-lead electrocardiogra-
phy. Subjects provided written informed consent in accordance
with guidelines established by the Institutional Medical Sci-
ences Subcommittee for the Protection of Human Subjects.
Descriptive characteristics of the subjects are shown in table 1.
Pretesting Exercise Evaluation
A previously described peak continuous multistage graded
exercise test that used a calibrated, hydraulically braked arm
ergometerb
was performed before CRT familiarization and
acute exercise testing.35 This test established the peak oxygen
consumption (VO2peak) and peak heart rate for each subject,
and allowed us to express their acute exercise responses on
both an absolute basis and as a percentage of their peak level
of exercise response. The ergometer seat was adjusted to match
the heights of the ergometer crank axis and the subject’s
shoulder joint, while allowing a slight bend of the elbow when
the crank handle was at the farthest point from the subject.
Testing was performed at 60rpm. Metabolic and cardiac re-
sponses to exercise were continuously monitored by open-
circuit spirometryc
and 12-lead electrocardiography.d
An initial
3-minute work interval was performed with a power output of
400kpm, with subsequent increases of power output equaling
100kpm for each 3-minute interval stage. Physiologic and
electrocardiographic exercise termination points were consis-
tent with the Guidelines for Exercise Testing and Prescription
of the American College of Sports Medicine.36 Peak work was
operationally defined as volitional exhaustion, inability to
maintain power output, or the point at which increasing work-
load failed to provoke further increase of V˙ O2.
Resistance Settings
Training and testing resistance settings were set to a standard
of 50% of the 1-repetition maximum (1-RM) for a series of 6
resistance exercises. To determine the absolute values for re-
sistance settings at this percentage of effort, isoinertial maxi-
mum strength was tested on a multistation exercise systeme
—
the same resistance equipment used for testing under the
MultiGym condition. Subjects performed 2 warm-up sets of 10
repetitions at each resistance station. The initial resistance for
each station was based on subject performance during the 2
warm-up sets, and targeted completion of 3 to 8 repetitions
during the third and final set. If subjects could complete 10
repetitions of an exercise while using good form and control,
the weight was increased to a resistance at which they could
Table 1: Descriptive Characteristics of the Study Subjects
Subject Age (y) Injury Duration (y) Weight (lb) Injury Level Gender Completed Study
1 43 16 186 T6 Male Yes
2 26 5 121 T4–5 Male Yes
3 20 3 145 T12–L1 Male Yes
4 43 5 138 T11 Male Yes
5 33 10 191 T6–7 Male Yes
6 28 2 133 T10 Male Yes
7 21 5 147 T12–L1 Male No
8 31 8 171 T6 Male Yes
9 22 3 153 T10 Male Yes
10 41 5 161 T4–5 Male No
11 33 10 144 T6 Male Yes
12 28 1 170 T6–7 Male Yes
13 21 6 234 T6–7 Female Yes
14 31 4 170 T6 Male Yes
15 21 1 212 T10 Male Yes
16 24 6 140 T6 Male Yes
17 45 1 170 T8–9 Male No
Mean 30.0 5.4
SD 8.6 3.9
Abbreviation: SD, standard deviation.
202 COMPARATIVE RESPONSES TO EXERCISE IN PARAPLEGICS, Nash

only perform 3 to 8 such repetitions. One repetition (1-RM)
strength was calculated by using the Mayhew regression equa-
tion:
1-RM ϭ Wt/͑.533 ϩ .419eϪ.055 ⅐ reps
͒
where 1-RM was the calculated 1-RM, Wt was the resistance
used in the final set of testing, and e the log to the base e.
Values calculated by using this procedure correlate very highly
(r ϭ .96) with the 1-RM obtained by direct testing.37
Once a 50% 1-RM was calculated for each subject, the
resistance for each exercise on the MultiGym system was
converted into Thera-Band resistance equivalents. To do this,
each of 8 Thera-Band colors was formed into 20-cm loops and
attached to a calibrated tensiometer. The bands were then
extended to a maximum length of 56cm, and the relation
between their distension and resistance established (table 2).
Exercise Familiarization and Acute Testing
Subjects underwent 2 weeks of training, which was per-
formed 3 times weekly for 45 minutes at each session (or
completion of 3 complete circuits). The resistance work per-
formed on both systems used a previously reported exercise
protocol29 that used alternating series of resistance and endur-
ance exercises, with periods of incomplete recovery (ie, heart
rate not falling to baseline) between each exercise. Station
changes were accomplished in less than 15 seconds. The circuit
training used 3 cycles of 6 resistance exercises performed in
pairs, with 2 minutes of interposed arm spinning. Performance
at each resistance station for a cycle was satisfied by the
execution of 1 exercise set containing 10 repetitions of the
maneuver by using 6-second contractions (3s concentric, 3s
eccentric each). All subjects completed the prescribed 10 rep-
etitions within a 1-minute period. Exercises and their order of
performance were as follows: (1) military press; (2) seated
rows; (3) 2 minutes of arm ergometry; (4) wide-grip latisimus
pull-down; (5) rickshaw; (6) 2 minutes of arm ergometry; (7)
pec deck; (8) preacher curls; and (9) 2 minutes of arm ergom-
etry. This circuit was completed 3 times.
Arm ergometryf
for the MultiGym condition was performed
at peak speed without applied resistance, whereas arm ergom-
etry for the ElasticGym condition used arm spinning in the air,
as though punching a speed bag placed at shoulder level (fig 2).
A chest press maneuver for the ElasticGym condition substi-
tuted for the pec deck on the MultiGym, and unsupported (free)
curls were used in place of preacher curls for testing of the
elbow flexors. Selected exercises undertaken during the Mul-
tiGym and ElasticGym testing and training are shown in figures
1 and 2.
In randomized fashion, subjects alternated training days by
using the MultiGym and ElasticGym systems. This training
allowed for habituation to both exercise systems, as well as the
circuit order and physical challenges.
Acute Testing
During the final 2 days of training, heart rate, V˙ O2, and
ratings of perceived exertion (RPE; Borg Scale of Perceived
Exertion [6–20]38) were recorded for each subject during a
single bout of exercise on each exercise system. The order of
system testing was randomized, and 48 hours of rest was given
between testing sessions. Oxygen consumption measured dur-
ing testing was assessed by a portable metabolic analyzerg
previously validated by Jacobs et al.35 Continuous heart rate
was measured by a chest strap heart rate monitor (with PC
interface for downloading data)h
and averaged across the entire
exercise bout. RPEs were recorded at the termination of work
as the subjects’ perception of whole-body effort.
Data Analysis
Data for V˙ O2 and heart rate reflected the averages measured
during complete exercise bouts. A within-subjects analysis of
variance was used to test differences in the test conditions
(MultiGym vs ElasticGym) for these dependent variables. A
nonparametric t test was used to test differences between the
test conditions for RPE. In both cases, the criterion for signif-
icance was set at P Յ .05.
RESULTS
All subjects tolerated the preparation and testing without
incident. Metabolic, chronotropic, and perceptual responses to
exercise under both conditions are shown in table 3. The
absolute V˙ O2 and average percentage of VO2peak were both
higher under MultiGym than under ElasticGym conditions,
though the differences between the conditions—.08L/min and
.05%—were neither clinically nor statistically significant. Nei-
ther the mean heart rate difference of 6 beats/min nor the heart
rate peak difference of .032% were significantly different (table
4). Conversely, the perceptual responses under ElasticGym
conditions (table 5) were nearly 1 point higher than those
recorded under the MultiGym condition (P Ͻ .05).
DISCUSSION
This research adresses 3 key issues for persons with para-
plegia. First, widespread reports of physical deconditioning and
dyslipidemia suggest a need for exercise training to reduce the
occurrence or to delay the appearance of cardiovascular dis-
eases among persons with paraplegia. Second, though many
studies examining exercise conditioning for persons with para-
plegia have used continuous resistive arm ergometry and
wheelchair ergometry as training modes, recent concern about
the long-term function of the upper extremities as persons age
with disability raises questions whether such exercise recom-
mendations are appropriate.25,39 Because many persons with
paraplegia require a wheelchair to perform daily tasks, such as
locomotion, weight shifts, and body transfers,40-42 the accumu-
lated effects of these tasks may hasten shoulder dysfunction,
and thus compromise both their health and independence as
they age.23,24,43,44 Although sedentary lifestyles and hyperlip-
idemia reported among paraplegia survivors confirm the need
for increased physical activity, in many cases endurance exer-
cise activities that use the neurologically intact muscles of the
upper body have only worsened shoulder, elbow, and wrist
pain.24,45 Last, CRT appears to satisfy the need for both car-
diorespiratory endurance and upper-extremity strengthening in
persons with paraplegia.29 The current study specifically ad-
dressed accessibility to CRT by designing a delivery system
Table 2: Matching of Thera-Band Level Resistance With
Equivalent Weight Used for Exercise on an Equalizer 7000
Multi-Station Exercise System
Thera-Band
Resistance Level
Weight Stack Level for
Equalizer 7000 (per loop), lb
Red 13.5
Green 20
Blue 25
Black 30
Silver 45
Gold 62.1
NOTE. Weight equivalent is for the full excursion of the Thera-Band
elastic bands.
203COMPARATIVE RESPONSES TO EXERCISE IN PARAPLEGICS, Nash

Fig 1. Representative exercises undertaken during ElasticGym and MultiGym training and testing: (A) latissiumus pulldown, (B) military
press, (C) horizontal rows, and (D) dips.

that is safe, efficacious, affordable, and requires only limited
space.
Despite the apparent need for strengthening persons aging
with SCI, and the recommendation of an authoritative body to
include resistance training in adult exercise conditioning pro-
grams,46 only 3 studies have examined upper-extremity
strength training for persons with paraplegia. Nilsson et al27
were the first to describe a program consisting of interval arm
exercise followed by progressive resistance exercise. Subjects
in their trial underwent 7 weeks of arm exercise performed 3
times weekly by using 3- to 4-minute bouts of activity per-
formed on a commercial stationary leg cycle adapted for hand
use. Each bout of cycling was then followed by triceps muscle
training performed in the sitting and supine positions. Training
results showed increased VO2peak (10.6%) and muscular
strength (18.8%), both of which were significantly less in
magnitude than results from training on a MultiGym system
using the algorithm reported in this study.29 Cooney and Walker28
trained subjects with hydraulic resistance equipment and mul-
tiple sets at 2 exercise stations, with controlled rest periods
of 40 to 100 seconds between sets. Improvements in cardio-
respiratory capacity of 28.1% and power output of 36.7% were
recorded after the 9-week training program, although no
strength-related outcomes were reported. Unlike other pro-
grams of CRT, in which station changes are made rapidly,
several wheelchair transfers were required to perform the ex-
ercises because the training equipment was not adapted for
wheelchair use. Davis and Shephard20 measured strength in
subjects with undescribed lower-limb disabilities undergoing
16 weeks of arm exercise conducted 3 times weekly on a
Monarch ergometer at 70% or 40% of measured VO2peak
uptake for either 40 or 20 minutes per session. Muscle strength
was operationally defined as the peak moment, peak power,
average power, and total work of shoulder and elbow flexion
and extension, and shoulder joint abduction and adduction at
isokinetic velocities ranging from 60° to 300°/s. Training re-
sults showed increased power in subjects who trained at higher
exercise intensities and longer durations, but favored maneu-
vers executed at higher, not lower, isokinetic testing speeds.
Unfortunately, the largest strength differences found after
training were for shoulder flexion and elbow extension in
subjects training at high work intensities. Unfortunately, these
muscle groups are neither the weakest nor those most in need
of strengthening for persons with SCI. Further, training at low
work intensities actually lowered peak and average power of
these muscles, suggesting that higher training intensities are
needed to increase muscle strength, and these needs are not
satisfied by intense arm ergometry.
CRT is a form of exercise conditioning in which a series of
exercises are sequentially performed—1 set per station—for a
prescribed number of circuits.47 The cardiorespiratory benefits
of CRT exceed those of training protocols that use resistance
exercises alone,31,47,48 with benefits determined by factors such
as exercise duration, the work-rest ratio, and the training in-
tensity.47 Six to 8 stations of such exercise are normally used
with rest periods between stations limited to 10 to 15 seconds.
In an earlier study,29 these guidelines were used to design a
CRT protocol, for persons with paraplegia, that used 6 resis-
tance maneuvers on a multistation isoinertial exercise machine
adapted for wheelchair users. Pairs of isoinertial maneuvers
alternated with low resistance, high rate arm ergometry suffi-
cient to maintain heart rate above resting baseline. Subjects
undergoing 12 weeks of such training experienced significantly
increased cardiorespiratory endurance and muscular strength.29
The average increase in VO2peak of 29.7% sustained by sub-
jects was greater than enhancements of aerobic capacity
reported after many extended programs of endurance arm
ergometry or wheelchair ergometry exercise conditioning.49
Increased upper-extremity isoinertial strength ranging from
12% to 30% was also reported. Unfortunately, the equipment
used for training the subjects in that study is priced beyond the
range of most home-based exercise users, and occupies con-
siderable space. Thus, we redesigned the CRT program to use
Fig 2. Arm spinning (A) with and (B) without an ergometer.

more economic resistance and endurance systems and to oc-
cupy less space.
The use of elastic bands for muscle strengthening has been
reported in many training studies. Resistance exercises that use
elastics have reportedly improved strength, flexibility, gait
stability, and endurance in older persons placed on home-based
training programs.50-55 The use of elastic bands for closed-
chain kinetic training of individuals undergoing anterior cruci-
ate ligament reconstruction has been found superior to that of
strengthening by open chain kinetic training, which uses con-
ventional physical therapy equipment.56 Elastic resistance has
also been used for upper-extremity rehabilitation in individuals
without shoulder pathology, and to target the strengthening of
rotator and upper-extremity muscles in young collegiate tennis
players.57 Despite the strengthening benefits of CRT elastic
resistance, only 1 study58 has reported its use for upper-extrem-
ity training in individuals with lower-extremity disabilities. By
using 5 resistance activities and an upper-extremity stretching
program, individuals in wheelchairs reduced their upper-ex-
tremity pain as assessed by the validated Wheelchair User’s
Shoulder Pain Index.59 Otherwise, we are unaware of any study
that used resistance bands in a circuit resistance format to
improve strength, endurance, and flexibility simultaneously.
Although these attributes were not directly tested in the current
study, there is a strong similarity between acute responses by
using resistance bands and responses elicited by a training
mode already known to increase strength and endurance. None-
theless, the effects of training on cardiorespiratory endurance
and upper-extremity strength now require confirmation.
Unlike many studies involving exercise training for persons
with paraplegia, the current investigation was conducted with
subjects similar in ages, levels of paraplegia, gender, and
somatotypes. Most were not participating in formal exercise
conditioning when they were recruited for the study, and their
Table 3: Comparison of VO2peak Responses to Arm Ergometry and the Acute V˙ O2 Responses (average and % of peak) to Exercise Under
MultiGym and ElasticGym Test Conditions (n ‫؍‬ 14)
Subject VO2peak (L/min)
MultiGym ElasticGym
V˙ O2mean (L/min) VO2peak (%) V˙ O2mean (L/min) VO2peak (%)
1 1.98 .79 40 .68 35
2 1.20 .54 45 .51 42
3 1.56 .64 41 .51 33
4 1.83 .75 41 .84 46
5 0.89 .54 61 .69 78
6 1.49 .55 37 .52 35
7 1.94 .58 30 .62 32
8 1.44 .61 42 .50 35
9 1.17 .71 61 .49 42
10 1.89 .81 43 .71 38
11 1.43 .61 43 .49 34
12 1.63 .65 40 .46 28
13 2.10 .65 31 .42 20
14 1.48 .52 35 .35 24
Mean 1.58 .64 42 .56 37
SD .34 .10 9 .13 14
Table 4: Comparison of Heart Rate Peak Responses to Arm Ergometry and the Acute Heart Rate Responses (average and % of peak) to
Exercise Under MultiGym and ElasticGym Test Conditions (n ‫؍‬ 14)
Subject
Heart Rate Peak
(beats/min)
MultiGym ElasticGym
Heart Rate Mean
(beats/min)
Heart Rate Peak
(%)
Heart Rate Mean
(beats/min)
Heart Rate Peak
(%)
1 195 140.5 72 130.6 67
2 193 123.4 64 129.4 67
3 143 111.9 78 123.8 86
4 184 134.2 73 120.8 65
5 188 122.6 65 105.0 56
6 177 120.2 68 113.0 64
7 197 122.2 62 123.0 63
8 182 112.2 62 100.1 55
9 172 127.8 74 117.5 68
10 196 148.2 76 106.2 54
11 164 115.8 71 137.6 84
12 150 119.3 80 119.2 80
13 188 103.3 55 97.3 52
14 188 130.4 69 118.5 63
Mean 179.17 123.7 69 117.3 66
SD 16.99 11.88 7 11.8 11

only common characteristic was neurologically complete in-
jury below the T4 level. That level was necessary to ensure
relatively normal and similar heart rate responses to exercise
because injuries above this level result in varying degrees of
cardiac sympathectomy and attenuated heart rate responses to
exercise.33 Two subjects more than 40 years of age tolerated
the exercise without complication, as did 2 subjects (1 man, 1
woman) who weighed well over 200 pounds each. No injuries
were sustained, though muscle soreness early in the habituation
phase of the study caused 1 subject to withdraw. Otherwise,
both this study and a previous report29 found the training safe
for exercise of deconditioned persons with paraplegia.
The rationale for selecting resistance intensity for this study
at 50% of the estimated 1-RM is worthy of discussion. Al-
though target intensities used for endurance training of persons
without disability are well established,36 far less is known of
the resistance targets necessary to meet the needs of persons
with disabilities. The selection of resistive exercises and their
intensities for the circuit were based, in part, on previous
reports that have described the most physically taxing activities
of normal daily living and also included concentric horizontal
rows. This maneuver effectively recruits rotator cuff muscles
when using elastic band resistance in persons who use wheel-
chairs as their mode of locomotion.60 The activities of wheel-
chair propulsion, body weight shifts, and depression transfers
are the tasks that require the greatest degree of muscular
effort,40-42 and during which persons with paraplegia experi-
ence the most weakness and pain.23 Because all of these activ-
ities are essential for performing daily activities, an under-
standing of the movements and muscles involved in their
performance, and the intensities of muscular contraction, ought
to serve as the best guides for designing an exercise training
program, to enhance the physical capacity of persons with
paraplegia. Such exercises should also attend to diseases of the
cardiopulmonary system and the decline of musculoskeletal
function, which currently represent major sources of morbidity
for persons aging with paraplegia.2,39
Among the novel findings of the study was the higher
perception of exertion when subjects underwent CRT by using
elastic resistance bands and no ergometer. The Borg Scale of
Perceived Exertion (6–20) normally correlates closely with
exercise responses, including percent VO2peak, percent heart
rate reserve (heart rate maximum Ϫ heart rate exercise), minute
ventilation, and blood lactate levels.61 Subject reports of per-
ceived exertion to both exercise systems tested in this study
were near level 13—defined as “somewhat hard”—with re-
sponses to ElasticGym testing a little above and MultiGym
testing a little below this level. When queried after completing
the study, subjects reported that the resistance component of
the ElasticGym exercise system was slightly less challenging
than was the isoinertial multistation exercise system. This
might have been anticipated because the targeted resistance of
Thera-Band is not reached until it is fully extended. Thus, the
50% of 1-RM intensity was reached only at the end range of
resistance maneuvers. In contrast, the isoinertial resistance
maneuvers were conducted at a constant external load of 50%
1-RM throughout the entire movement range. This inequality
in resistance was likely diminished during ElasticGym exercise
by the need for greater use of muscle assisters and stabilizers.
In contrast, our subjects found spinning of the arms in the air
without an ergometer far more challenging than using a com-
mercial arm ergometer. Two possible explanations for these
reports were: (1) subjects were not restricted in the speed of
their spinning arms by the fly wheel and resistance mechanism
of an ergometer, and (2) the exercise required isometric shoul-
der joint abduction to maintain the arms away from the body.
This contrasted significantly with the minimal shoulder stabi-
lization required for propulsion of an arm ergometer.
CONCLUSION
Metabolic and heart rate responses of subjects with chronic
paraplegia to exercise on a multistation isoinertial exercise
system matched those observed when the subjects underwent
CRT using elastic resistance bands. Perceptual responses of
exertion were higher when the exercise was conducted with
elastic bands and when using arm spinning rather than a com-
mercial arm ergometer. The higher perceived exertion may be
attributed to the need for self-stabilization of resistance ma-
neuvers, and the need to hold the arms in the air when per-
forming arm spinning without an ergometer. The effect of CRT
when using an elastic resistance system on the development of
strength and endurance in individuals with chronic paraplegia
requires further investigation.
Acknowledgments: The authors thank Phil Page, MS, PT, ATC,
for consultation on the resistance characteristics of Thera-Band.
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Table 5: Acute Perceptual Responses (Borg Scale of Perceived
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Conditions Averaged Across the Entire Exercise Bout (n ‫؍‬ 14)
Subject MultiGym ElasticGym
1 11.3 12.0
2 12.0 14.0
3 12.7 14.3
4 16.3 16.5
5 14.0 14.5
6 14.3 15.3
7 12.7 12.0
8 11.8 11.7
9 13.0 13.5
10 14.6 15.0
11 12.1 13.4
12 10.0 12.8
13 12.1 12.2
14 9.7 11.3
Mean 12.6 13.5*
SD 1.8 1.5
* Denotes a significant effect of test condition at P Ͻ .05.

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Pkwy, Loma Linda, CA 92887.
d. Fukuda-Denshi USA Inc, 17725 NE 65th St, Bldg C, Redmond,
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e. Equalizer 7000 Multi-Station Exercise System; Helm Distributing
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g. Aerosport Teem 100 or Kb1C; Medical Graphics Corp, 350 Oak
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