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Author`s personal copy - Cairo University Scholars
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burns 40 (2014) 97–105
Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.elsevier.com/locate/burns
Effect of isokinetic training on muscle strength, size
and gait after healed pediatric burn: A randomized
controlled study
Anwar Abdelgayed Ebid a,1,*, Shamekh Mohamed El-Shamy b,
Amira Hussin Draz c
a
Department of Surgery, Faculty of Physical Therapy, Cairo University, Giza, Egypt
Department of Growth and Developmental Disorders in Children and its Surgery, Faculty of Physical Therapy, Cairo
University, Giza, Egypt
c
Department of Basic Science, Faculty of Physical Therapy, Cairo University, Giza, Egypt
b
article info
abstract
Article history:
Objective: The aim of this study was to investigate the effects of isokinetic training program
Accepted 21 May 2013
on muscle strength, muscle size and gait parameters after healed pediatric burn.
Design: Randomized controlled trial.
Keywords:
Subjects: Thirty three pediatric burned patients with circumferential lower extremity burn
Pediatric burn
with total body surface area (TBSA) ranging from 36 to 45%, and ages from 10 to 15 years
Isokinetic strength
participated in the study and were randomized into isokinetic group and a control group.
Gait
Non-burned healthy pediatric subjects were assessed similarly to burned subjects and
Rehabilitation
served as matched healthy controls.
Methods: Patients in the isokinetic group (n = 16) participated in the isokinetic training program
for 12 weeks for quadriceps dominant limb, 3 times per week, at angular velocity 1508/s,
concentric mode of contraction, time rest between each set for 3 min, 3 sets/day and control
group (n = 17) participated in home based physical therapy exercise program without isokinetic.
Main measures: Assessment of quadriceps strength by isokinetic dynamometer, quadriceps
size and gait parameters were performed at baseline and at the end of the training period for
both groups.
Results: Patients in isokinetic group showed a significant improvement in quadriceps
strength, quadriceps size and gait parameters as compared with those in the control group.
Quadriceps strength and percentage of improvement was 79.25 0.93 Nm (68.40%) for isokinetic group and 51.88 1.31 Nm (9.84%) for the control group. Quadriceps size and percentage of improvement was 31.50 0.89 cm (7.47%) for isokinetic group and 29.26 1.02 cm
(1.02%) for the control group. Stride length, step length, velocity and cadence and percentage of
improvement for isokinetic group was 135.50 2.82 (53.97%), 63.25 2.97 (63.77%),
135.94 1.65 (81.42%), 137.63 1.36 (66.96%) and for the control group was 94.00 2.69
(6.68%), 43.76 1.34 (15.15%), 81.11 1.91 (8.6%), 90.35 1.32 (9.01%) respectively.
Conclusions: Participation in the isokinetic training program resulted in a greater improvement in quadriceps muscle strength, size and gait parameters in pediatric burn.
# 2013 Elsevier Ltd and ISBI. All rights reserved.
* Corresponding author. Tel.: +966 534024566/+20 1005253313.
E-mail addresses: [email protected], [email protected] (A.A. Ebid).
1
Member of Rehabilitation Research Chair (RRC), College of Applied Medical Sciences (CAMS), Umm Al-Qura University.
0305-4179/$36.00 # 2013 Elsevier Ltd and ISBI. All rights reserved.
http://dx.doi.org/10.1016/j.burns.2013.05.022
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1.
burns 40 (2014) 97–105
Introduction
Severe burns lead to a change in patient metabolism that may
persist for over 24 months after the initial event [1]. The
ensuing period of hypermetabolism and catabolism following
a burn leads to impaired immune function, decreased wound
healing, erosion of lean body mass (LBM), hinders rehabilitative efforts and reintegration into society is delayed and
quality of life impaired [1,2].
There are at least two major factors that contribute to
muscle deconditioning after major burn: bed rest and
catabolic processes that lead to muscle atrophy. A serious
burn results in the greatest hypermetabolic response in
comparison with other physical traumas [3]. Increased
metabolic rate can persist until wound closure is achieved
[4] and perhaps for 6–9 months after wound closure [5].
Prolonged states of hypermetabolism result in catabolic
consequences that may not be recognized in the acute phase
of the injury but can later cause significant muscle wasting
and deconditioning.
Strategies for attenuating the maladaptive response after
burn [6,7] can be divided into non-pharmacological and
pharmacological approaches. The non-pharmacological approach includes early excision of burned skin and closure of
wounds, pertinacious surveillance for and treatment of sepsis,
early commencement of high-protein high-carbohydrate
enteral feeding, elevation of the immediate environmental
temperature to over 30 8C; and enrollment in an aerobic/
resistance exercise program. This integrative approach has
been shown to improve outcome [8–10].
Survival rates after severe burn have significantly improved in the past two decades [11,12]. This progressive
decline in mortality has highlighted the importance of
physical rehabilitation after burn to maximize the recovery
of physical function. Typically, standard physical and occupational rehabilitation therapy targets the improvement of
overt physical changes associated with burn, such as
uncomfortable scarring, range of motion (ROM) limitations,
and contractures [13].
Independence in locomotion is the single variable that
discriminated between patients who went home after discharge from those who were discharged to another institution.
Thus, factors affecting locomotion, such as fatigue and muscle
deconditioning, are also important during the rehabilitation
phase of burn recovery [14].
Prevention and treatment of deconditioning and muscle
wasting are emerging as important areas for research in burn
rehabilitation. Exercise has been shown to counteract the
muscle-wasting effects of age and inactivity [15,16].
Resistance training for several weeks increases muscle
cross-sectional area, strength, and power [17]. Muscular
hypertrophy and strength gains following resistance training are thought to be dependent on the intensity of exercise
[18].
Isokinetic training caused significant increases in type II AB
cross sectional area, with a tendency toward reduction in type
II B muscle fibers. Isokinetic training probably imposed
different loads on the muscle examined. Also, the isokinetic
training had a combination of resistance and endurance
characteristics, imposed under constant speed throughout the
whole range of motion [19].
Despite the extensive amount of literature on the effects of
resistance exercise in healthy non-burned children, there is a
lack of data on the effects of isokinetic exercise training on
muscle strength, muscle size and gait parameters in children
with burn. Therefore, we designed this study to assess
whether children with burn would benefit from an isokinetic
exercise training program by increasing muscle strength,
muscle size and improve gait parameters.
2.
Materials and methods
This was a 12-week blinded randomized controlled trial with
two measurement points’ baseline (pre) and 12 weeks (post)
Fig. 1. The assessors were blinded to the participants’ treatment
assignments. Healed pediatric burned children (male and
female) aged 10–15 years were recruited from Umm Almasrieen
General Hospital, Giza, Egypt by instructing two physical
therapists who were working in the burn unit to report all
patients who fulfilled the inclusion criteria of the study and had
no exclusion criteria. All participants’ relatives provided
informed consent form giving agreement to participation and
publication of the results of the study. The burned children were
categorized as having a circumferential lower limb deep second
to third degree thermal injury extends from the lower trunk to
the foot. They received the same medical care and physical
Fig. 1 – Flow diagram of the study.
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burns 40 (2014) 97–105
therapy program during the acute stage which includes:
(positioning, range of motion, stretching exercise for lower
limb muscles, daily walking, and exercise). All participants were
asked to maintain their regular diet, normal daily activities and
lifestyle throughout the study. Inclusion criteria: burned
children, with percentages of burn ranged from 36 to 45% total
body surface area, non-athletes and were being ambulatory
without the use of an assistive device. The exclusion criteria
include diabetes, neuropathy, neurological disorders, severe
behavior or cognitive disorders, leg amputation, participation in
any rehabilitation program prior to the study [20,21], any
medication that could affect strength adaptations and adversely affect the results of the study, previous brain injury or any
disease affecting balance, vestibular or visual disorders, lower
limb deformity and history of epilepsy.
Patients were randomly assigned to one of two groups;
isokinetic group who received 12 weeks isokinetic training
program on biodex system (Biodex Medical System, Shirley,
NY, USA) plus home based physical therapy program (Range
of motion exercise, splinting, stretching exercise for lower
limb muscles, daily walking, functional training for ambulation and activities of daily living) and control group who
received the same home based physical therapy program
without isokinetic training. The numbers of participants in
the study at each stage are shown in the CONSORT diagram
in Fig. 1. All participants in this study follow exercise
guidelines prescribed the exercise performed at home (three
days/week) regarding the intensity, type and duration to
control any variation between groups and no exercise done
in the rest of the week. Random assignment of patients was
conducted in two stages. Stage one involved instructing two
physical therapists who were working in the faculty of
physical therapy outpatient clinic to report all patients who
fulfilled the inclusion criteria of the study (Registration
diagnosis, age, total body surface area burned) and had no
exclusion criteria. The second stage involved randomly
assigning the patients to either the isokinetic group or the
control group, random process that involved opening an
opaque envelope prepared by an independent person with
random number generation. The randomization process
was carried out by a registration clerk who was not involved
in any part of the study. Outcome measures: includes
quadriceps strength by using isokinetic dynamometer,
quadriceps size by using tape measurement and selected
gait parameters (stride length, step length, velocity and
cadence,) by using GAITRite system.
Non-burned healthy controls: the burned patients were pairmatched with 20 unburned healthy subjects who were
recruited from the community. All variables were assessed
similarly to burned subjects and served as matched healthy
controls. They were paired as closely as possible to the burn
subjects for sex distribution and age.
2.1.
Evaluation of muscle strength
Evaluation of muscle strength for all patients began after
discharge. The subjects were asked to complete the personal
data that included the subject’s name, age, address and
telephone number. The height and weight of each subject
were recorded from the height and weight scale.
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Each child was allowed to ask any question about any part of
the study; thus, the idea and the testing procedures of the study
became clear for all subjects. The therapist performed the initial
evaluation of knee extensor muscles of the dominant burned
limb with Biodex isokinetic dynamometer (Biodex Medical
System, Shiley, NY, USA, linked to IBM PC-computer software)
.Calibration of the Biodex for torque and angular velocity was
performed according to the manufacturer’s instructions prior to
each recording session. After a 5-min warm-up on the treadmill
without resistance, hot packs were applied for 15 min to the
quadriceps; the participants stretched the quadriceps muscles
of both limbs. Each muscle group was stretched 5 times for 30 s
alternately for 5 min [22,23]. Following the warm-up, the
participants were positioned in an isokinetic dynamometer
with hip angle of 1008. The trunk, pelvis and thigh were
stabilized using straps, in accordance with the Test and
Rehabilitation System User’s Guide of Biodex.
The participants familiarized themselves with the testing
and training procedures: (1) the test procedure was demonstrated and explained to the patients and (2) patients were
allowed to practice the actual movement during the three submaximal repetitions without load as warm-up. More repetitions were not allowed to prevent the onset of fatigue. The
anatomical axis of rotation of the dynamometer were visually
aligned to the axis of rotation of the knee joint before the test,
while the isokinetic test was performed at an angular velocity
of 1508/s. We used this speed versus lower or higher angular
speeds, because it was well tolerated by the burned patient
[24]. After the three sub-maximal warm up repetitions, more
repetitions were not permitted so as to prevent fatigue. After
warm-up repetitions, subject’s performed 10 maximal voluntary muscle contractions consecutively without rest in
between. Three minutes of rest were given to minimize the
effects of fatigue, and the test was repeated. Verbal encouragement, as well as visual feedback from the equipment, was
given in an attempt to achieve a maximal voluntary effort level
during all the contractions that each participant was asked to
perform [23]. Values of peak torque were calculated by the
Biodex software system.
2.2.
Evaluation of quadriceps size
Tape measurement used for assessment of quadriceps size
(round measurement) for both groups at baseline and at the
end of 12 weeks. The measurements were performed in a quiet
room for quadriceps dominate leg at mid-thigh (MT) level
which was taken as the midpoint between the upper pole of
the patella and the anterior superior iliac spine. Measurements were performed at these locations to detect change in
quadriceps size after isokinetic training. The measurement
was taken with the quadriceps relaxed and without compression of the skin. The sequence of measurements was repeated
three times at mid-thigh level by the same examiner in the
same order. Circumferential measurements were recorded to
the nearest 0.1 cm with an ordinary tape measure.
2.3.
Evaluation of gait parameters
The GAITRite system (GAITRite Gold software, PA, USA) is an
electronic walkway that is connected to a personal computer
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burns 40 (2014) 97–105
Table 1 – Demographic characteristics of burned patients and non-burned healthy control.
Burned
Control group (N = 17)
Gender
Age (years)
Height (cm)
Weight (kg)
TBSA
Average % TBSA of LE
Average length of hospitalization
Non-burned
Isokinetic group (N = 16)
11 male/6 female
13.60 1.12
140.06 2.93
48.0 2.85
42.40 3.13
25 2.6
32.29 2.71
10 male/6 female
13.46 1.18
140.2 3.30
48.86 2.92
42.06 3.08
26 2.8
31.87 2.75
Healthy (N = 20)
9 male/11 female
14.20 1.15
142.10 2.19
47.10 1.74
There were no significant differences between burn groups, no significant differences between all patients and non-burned.
via an interface cable. Children were given standardized
instructions to walk at their preferred walking speed bare
footed. Parent or investigator verbally encouraged child to
complete the gait task from the opposite end of the GAITRite
mat to walk the entire length of the mat.
Children completed at least 4 barefooted walks, each
totaling a 7.66 m, which included 2 m off either end of the
GAITRite mat for purposes of acceleration and deceleration.
Notes were recorded regarding any unusual gait patterns.
Subjects were asked to repeat any trial that had less than 4
steps on the GAITRite mat. Less than 1% of the trials were
labeled mistrials. The mistrials occurred secondary to a
child running down the mat and getting fewer than 4
footfalls on the mat surface or walking off the mat before 4
footfalls were recorded. Data on velocity (cm/s), cadence
(steps/min), step length (centimeters), stride length (centimeters) was collected via computers. Several studies
have reported the reliability and validity of measuring
gait parameters using the GAITRite in healthy adult subjects
[25]. Several authors [26–28] concluded that the GAITRite
electronic walkway is an emerging clinical tool for
the assessment of gait in children with and without
disabilities.
2.4.
Isokinetic training protocol
The isokinetic training protocol was started after the initial
evaluation and was performed 3 times a week for 12 weeks
(36 sessions). Each session included a 5-min warm-up
period on a treadmill at a velocity of 4 km/h, followed by
five sets of quadriceps stretching as previously described
[23,24]. Fifty percentages of average peak torque were
selected as the initial dose of isokinetic exercise, and an
increasing dose program was used in the first to fifth
sessions (one set to five sets), and a dose of six sets was
applied from the sixth to the 24th session and, finally, a dose
of 10 sets was applied from the 25th to the 36th sessions.
Each set consists of 10 repetitions concentric contraction at
an angular velocity of 1508/s and patients were allowed
3 min of rest between sets [23]. Verbal encouragement, as
well as visual feedback from the equipment, was given in an
attempt to achieve a maximal voluntary effort level during
all the contractions that each participant was asked to
perform [22]. Values of peak torque were calculated by the
Biodex software system.
3.
Data analysis
All data were examined using SPSS version 16.0. Descriptive
statistics used to compare demographic characteristics of all
groups. Our data were normally distributed which tested by
Shapiro–Wilk test and the data were collected and statistically
analyzed using repeated measures ANOVA to test hypothesis
and to control both within and between variabilities. Results
are reported as means and standard deviations. For all
procedures, significance was accepted at the alpha level of
0.05.
4.
Results
For this study, fifty burned patients were identified as
potential participants Fig. 1. Of these, eight were excluded
because they failed to fulfill the inclusion criteria and five
refused to participate in the study; Finally 33 pediatric patients
with healed burn included in the study .The demographic
characteristics of participants in both groups are listed in
Table 1. Prior to the training period, there was no difference in
the age, weight, height, gender distribution and body mass
index among all groups ( p > 0.05) as in Table 1. The average
length of hospitalization for control and isokinetic group was
(32.29 2.71 days vs 31.87 2.75 days), the average lowerextremity (LE) TBSA burned was (25 2.6 and 26 2.8) and the
length of time between injury and initial evaluation before the
study was (42.25 3.49 vs. 44.35 3.95 days) respectively were
similar in both groups of patients ( p > 0.05).
4.1.
Quadriceps strength
The mean values of peak torque for quadriceps muscle are
reported in Table 2. Peak torque values of quadriceps muscle
for non-burned healthy control subjects were 92.10 1.37 Nm.
In all burned patient’s peak torque values for quadriceps were
47.15 0.97 Nm. There was a significant difference in the
amount of peak torque between the burned and non-burned
healthy control subjects. The burned group had 95.33%
decreased peak torque for quadriceps compared with age
non-burned healthy subjects at the beginning of the study.
The data concerning the non-burned healthy control (peak
torque as mean SD) was presented in Table 2.
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burns 40 (2014) 97–105
Table 2 – Mean values of quadriceps torque for burned patients and non-burned healthy control.
Mean values of quadriceps peak torque (Nm)
Burned
Non-burned
Control group
Pre
Mean SD
F value, p
% of improvement
Isokinetic group
Post
47.23 0.97
163.64, <0.001*c
9.84%
Pre
Healthy
Post
51.88 1.31
47.06 0.99
3212.90, <0.001*c
10,174.87, <0.001*c
68.40%
79.25 0.93
92.10 1.37
Values are mean SD. cDF (degree of freedom) = 1.31 **Non significant. *Significant.
Table 3 – Mean values of quadriceps size for burned patients and non-burned healthy control.
Mean values of quadriceps size
Burned
Non-burned
Control group
Pre
Mean SD
29.26 1.01
F value, p
% of improvement
4.53, >0.001**c
1.02%
Isokinetic group
Post
Pre
29.56 1.01
29.31 0.94
20.20, <0.001*c
35.90, <0.001*c
7.47%
Healthy
Post
31.50 0.89
34.75 0.96
Values are mean SD. cDF = 1.31. **Non significant. *Significant.
Fig. 2 – Mean values of quadriceps torque for burned
patients and non-burned healthy control.
There was a significant increase in peak torque after 12
weeks in the isokinetic group and control group with favor to
isokinetic group. Peak torque of quadriceps was 79.25 0.93
Nm vs. 51.88 1.31 Nm. The isokinetic group had 68.40% vs.
9.84% increased peak torque compared with the control group.
Comparison of the mean percent change obtained revealed a
significant increase in peak torque in the isokinetic group
compared to the control group (Fig. 2).
4.2.
decreased quadriceps size compared with age non-burned
healthy subjects at the beginning of the study. The data
concerning the non-burned healthy control (peak torque as
mean SD) was presented in Table 3.
There was a significant increase in quadriceps size after 12
weeks in the isokinetic group (p < 0.01) and non-significant
increase for control group (p > 0.001). Values of quadriceps
size were 31.50 0.89 cm vs. 29.56 1.01 cm. The isokinetic
group had 7.47% vs. 1.02% increased peak torque compared
with the control group. Comparison of the mean percent
change obtained revealed a significant increase in quadriceps
size in the isokinetic group compared to the control group
(Fig. 3).
4.3.
Gait parameters
The mean values of gait parameters are reported in Table 4.
Values of stride length, step length, velocity and cadence for
Quadriceps size
The mean values of quadriceps size are reported in Table 3.
Values of quadriceps size for non-burned healthy control
subjects were 34.75 0.96 cm. Quadriceps size in all burned
patients was 29.24 0.96 cm. There was a significant difference in the quadriceps size between the burned and nonburned healthy control subjects. The burned group had 18.84%
Fig. 3 – Mean values of quadriceps size for burned patients
and non-burned healthy control.
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burns 40 (2014) 97–105
Table 4 – Mean values of gait parameters for burned patients and non-burned healthy control.
Mean values of gait parameters
Burned
Non-burned
Control group
Pre
Stride length (cm)
F value, p
% of improvement
Step length (cm)
F value, p
% of improvement
Velocity (cm/s)
F value, p
% of improvement
Cadence (step/min)
F value, p
% of improvement
88.11 2.28
70.36, <0.001*c
6.68%
38.00 1.83
103.82, <0.001*c
15.15%
74.70 1.53
97.97, <0.001*c
8.6%
82.88 1.53
578.61, < 0.001*c
9.01%
Isokinetic group
Post
Pre
94.00 2.69
88.00 2.09
1437.98, <0.001*c
3112.06, <0.001*c
53.97%
43.76 1.34
38.62 1.14
435.27, <0.001*c
1195.34, <0.001*c
63.77%
81.11 1.91
74.93 1.38
4169.13, <0.001*c
13,530.90, <0.001*c
81.42%
90.35 1.32
82.43 1.54
8005.51, <0.001*c
15,740.69, <0.001*c
66.96%
Healthy
Post
135.50 2.82
150.40 1.98
63.25 2.97
74.60 1.35
135.94 1.65
135.40 1.18
137.63 1.36
148.35 1.38
Values are mean SD. cDF = 1.31. **Non significant. *Significant.
non-burned healthy control subjects were150.40 1.98 cm,
74.60 1.35 cm, 135.40 1.18 cm/s and 148.35 1.38 step/
min. Stride length, step length, velocity and cadence in all
burned patients was 88.06 2.16 cm, 38.30 1.55 cm,
74.81 1.44 cm/s and 82.66 1.53 step/min. There was a
significant difference in the stride length, step length, velocity
and cadence between the burned and non-burned healthy
control subjects. The burned group had 70.79%, 94.77%,
80.99%, and 79.47% decreased stride length, step length,
velocity and cadence respectively compared with age nonburned healthy subjects at the beginning of the study. The
data concerning the non-burned healthy control (peak torque
as mean SD) was presented in Table 4.
There was a significant increase in stride length, step length,
velocity and cadence after 12 weeks in the isokinetic group and
control group. Values of stride length, step length, velocity
and cadence were 135.50 2.82 cm vs. 94.00 2.69 cm,
63.25 2.97 cm vs 43.76 1.34 cm, and 135.94 1.65 cm/s vs
Fig. 4 – Mean values of gait parameters for burned patients
and non-burned healthy.
81.11 1.91 cm/s and 137.63 1.36 step/min vs 90.35 1.32
step/min. The isokinetic group had 53.97%, 63.77%, 81.42% and
66.96% vs. 6.68%, 15.15%, 8.6% and 9.01% increase in stride
length, step length, velocity and cadence compared with the
control group. Comparison of the mean percent change
obtained revealed a significant increase in stride length, step
length, velocity and cadence in the isokinetic group compared
to the control group (Fig. 4).
Finally, there was statistically significant improvement in
quadriceps strength, quadriceps size, and gait parameters
were observed between subjects in the isokinetic group and
their non-burned healthy control subjects after 12 weeks of
training. By contrast quadriceps strength, quadriceps size, and
gait parameters were not completely recovered in the
isokinetic group compared with their non-burned matched
healthy controls after 12 weeks.
5.
Discussion
The purpose of this study was to investigate the effect of
isokinetic training program on quadriceps muscle strength
(force producing capacity), quadriceps size and selected gait
parameters (velocity, cadence, step length and stride length)
after healed pediatric burn.
Our results indicate that there is an increase in muscle
strength, muscle size and improve gait parameters in the
isokinetic group after 12 weeks of isokinetic training program
and this increase is not observed in the control group. Also, our
results are in agreement with reported strength gains in nonburned children who trained using various resistance exercise
protocols [29].
Prevention and treatment of deconditioning and muscle
wasting are emerging as important areas for research in burn
rehabilitation. Exercise has been shown to counteract the
muscle-wasting effects of age and inactivity [15,16].
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burns 40 (2014) 97–105
The mechanisms underlying muscular adaptations involve
many factors, that is, mechanical, metabolic, endocrine and
neural factors, of these factors; training-induced muscular
hypertrophy might be at least partially related to the
secretions of endogenous anabolic hormones such as growth
hormone (GH) and testosterone (TES) [30].
The normal physiological response to resistance training is
reported to be increased neural activation and muscle
hypertrophy [31,32]. Suman et al. [20] believed that neural
adaptation predominates in the early phase of training and
hypertrophy in the later phase.
Despite increases in strength, muscle size and improve gait
parameters found in our study, muscle weakness, decrease
muscle size and deviated gait parameters seems to persist, as
reflected by the low absolute peak torque values, muscle size
and gait parameters compared with non-burned children of
similar age, height, and weight.
Isokinetic concentric training is an adequate stimulus for
neural factors that contribute to strength gains in the training
program. Neural factors were an important determinant in
torque gains in training protocols. Also training of skeletal
muscle by using isokinetic protocol is more effective and safe
for rehabilitation of skeletal muscle torque after burn,
because isokinetic machine stimulates neural mechanisms
and enzymatic activity which lead to perfect action of skeletal
muscles and increase the resistance of the muscle for fatigue
[33].
Concentric muscle actions performed on isokinetic or
accommodating-resistance machines, or concentric muscle
actions only performed by weight lifting, have increased
directly measured muscle cross sectional area (CSA), limb
girth, or muscle fiber cross sectional area [34–37].
Isokinetic training protocol increases the mean peak torque
output of skeletal muscle group. The significant improvement
in strength obtained following training protocol is the result of
neural adaptations by allowing better activation of the motor
neuron pool and decrease fatigue of muscle, so the isokinetic
training program leads to significant increase in muscle
performance [38].
The torque gains in response to training are caused by
adaptive changes in muscle or neural control. Muscle can
adapt to a strength training program with hypertrophy or
adequate stimulant for increase enzyme activity of glycolytic
and mitochondrial enzyme [33].
Isokinetic training protocols induce skeletal muscle
hypertrophy on three types of muscle fibers I, IIa and IIb also
it increase the functional capacity of the all skeletal muscle
fibers with significant increase in peak torque of skeletal
muscle after training protocols [38] this is supported by Myer
et al. [39] who reported that neuromuscular training protocols
by using isokinetic that include both plyometrics and
dynamic balance exercises can significantly improve biomechanics and neuromuscular performance and reduce ligamentouse injury.
Our results were consistent with the results of Dragana
et al. [40] who reported that the implemented isokinetic
training protocols significantly improved the strength of the
thigh muscles measured isokinetically and decreased the
degree of muscle strength asymmetry. It is clear that the
isokinetic training protocol evoked greater changes in thigh
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muscle strength compared with isotonic training protocol,
which is reflected in greater changes in the ipsilateral
concentric ratio [40].
One of the consequences of severe burn is the significant
loss of muscle mass [20]. Our results concerning the
improvement of quadriceps strength and quadricepse size
after 12 weeks was supported by Suman et al. [20] who stated
that increase in muscle mass was observed in his population
because of the initially extreme low level of muscle mass and
conditioning. Ramsay et al. [32] speculated that the plateau
they found in leg strength midway through a 20-weeks
exercise program in healthy children may have been due to
the initial higher level of conditioning of knee extensors. Thus
the training stimulus needed to produce a response (i.e.,
hypertrophy) may be much less in the frail, burned child than
in healthy counterparts [20].
Increases in strength after heavy-resistance training are
due to muscular and/or neural adaptations. Muscular adaptations include an increase in the CSA of the prime movers
(muscle hypertrophy) or adaptations that increase specific
tension (force per unit CSA). Neural adaptations include
increased prime mover motor unit activation, increased
activation of synergistic muscles, or decreased activation of
antagonistic muscles [41].
Verbal feedback and visual feedback not affect the peak
torque output and gait parameters; this was consistent with
the conclusions of Barbara et al. [42] who stated that peak
torque executed during isokinetic sets is not significantly
altered by the presence of visual and verbal feedback.
Our results show a significantly greater increase in
functional physical performance such as strength, muscle
size and gait parameters due to the isokinetic training
program and learning effects and this was consistent with
Mark [43], who stated that, there are some specific considerations when undertaking strength testing to pediatric groups
such as adaptation of equipment, stabilization and technique,
habituation and learning effects, and safety.
Increase in muscle strength and ability to walk in a
satisfactory manner should result in an improvement in the
burned child’s capability to return to normal activities of daily
living, in addition to increased emotional and physical
independence and self-confidence. However, the association
between physical status and emotional and physical independence in burned children is presently unknown.
Using an isokinetic training program as a way to prevent or
attenuate further deterioration of muscle catabolism seen in
burned patients. Our results indicate that, in children with
>40% TBSA burned, an isokinetic training program based on
progressive load is successful in improving strength, muscle
size and gait patterns. The isokinetic training program in our
study based on progressive load which decrease the fact of
learning effect of the isokinetic training; also the improvement of muscle size and gait parameters is related to
the progressive pattern of our program. Finally, our results
demonstrate that severely burned children gain muscle
strength, muscle size and improve gait patterns by participating in an isokinetic training program and that such
a program should be a fundamental component of multidisciplinary outpatient treatment for victims of thermal
injury.
Author's personal copy
104
6.
burns 40 (2014) 97–105
Conclusions
Our results show that the isokinetic training program
performed 3 times a week for 12 weeks, significantly improves
quadriceps strength, size and gait parameters in children
after burn.
Conflict of interest
None declared.
Acknowledgements
The authors thank the patients and volunteers who participated in this study. Also, I would like to thank all staff
members working in the burn unit in Umm Almasrieen
hospital and outpatient clinic in the faculty of physical
therapy, Egypt for technical help and general support.
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