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OJHAS Vol. 10, Issue 2:
(Apr-Jun 2011) |
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Effect of
Dynamic Platform Lateral Step-Up versus Stable Platform Lateral Step-Up
Weight Bearing Exercise in Hip Abductor Strengthening on Healthy Male
Volunteers - Randomized Clinical Trial |
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Jagatheesan Alagesan, Associate
Professor, KJ Pandya College of Physiotherapy, Sumandeep Vidyapeeth,
Vadodara, India,
Anandbabu Ramadass,
DPT Scholar, Loma Linda University, Loma Linda, CA, USA |
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Address for Correspondence |
Associate
Professor,
KJ Pandya College of Physiotherapy,
Sumandeep
Vidyapeeth,
Piparia,
Waghodia, Vadodara - 391760,
India.
E-mail:
jagatheesanmpt@yahoo.com |
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Alagesan J, Ramadass A.
Effect of
Dynamic Platform Lateral Step-Up versus Stable Platform Lateral Step-Up
Weight Bearing Exercise in Hip Abductor Strengthening on Healthy Male
Volunteers - Randomized Clinical Trial. Online J Health Allied Scs.
2011;10(2):15 |
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Submitted: May 4,
2011; Accepted: Jul 16, 2011; Published: Jul 30, 2011 |
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| Abstract: |
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Objective
& Background: To
determine the effect of the dynamic platform lateral step-up and stable
platform lateral step-up weight bearing standing exercise in strengthening
of hip abductor. Many researchers have reported that strengthening of
hip muscles as important component especially hip abductors in lower
extremity rehabilitation program. Study Design: Single
blinded randomized comparative clinical trial.
Methodology: Sixty
five healthy college going male subjects (Age group of 18 – 24 years)
volunteered for this study. They were randomly assigned to one of the
2 groups. One group received the dynamic platform lateral step-up and
the other received stable platform lateral step-up weight bearing standing
exercise. The strength measurements were recorded using hand held dynamometer.
Results: The
results indicate that both groups had a positive effect on the outcome
measures. The strength of hip abductors in dynamic platform group
improved from a mean value (SD) of 19.47(3.59) to 26.93(3.19) and in
stable platform group from 19.07(2.32) to 22.67(2.46). Significant difference
is also observed between the two groups at p value .05. Conclusion:
The
study shows that dynamic platform lateral step-up exercise is more beneficial
than stable platform lateral step-up weight bearing standing exercise
in improving hip abductor muscle strength.
Key Words:
Hip
Strength; Hip Abduction; Strengthening Exercises; Dynamic Platform
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Muscle
strength is a broad term that refers to the ability of contractile tissue
to produce tension and a resultant force based on the demands placed
upon the muscle.(1) Muscular strength is an important factor in determining
the effectiveness of the work done.(2,3)
The
gluteus medius is described as a strong abductor and medial rotator
of the hip joint. During the stance phase of gait, the gluteus medius
is supported to prevent the sagging of the pelvis on the unsupported
side. The action of the gluteus minimus is said to be similar to that
of gluteus medius. (4) Neumann and colleagues (5-7) reported that electromyography
(EMG) activity of hip abductors during the stance phase of walking increases
when carrying a load in the hand contralateral to the given hip abductors.
Hip
muscle weakness is frequently found following hip injury, orthopaedic
surgeries around the hip and degenerative joint disorders. Hip
muscle weakness could lead to patellofemoral malalignment and development
of patellofemoral pain.(8-10) Hip abductor weakness is also reported
in long distance runners with Illio Tibial Band syndrome.(11) Delayed
hip abductor muscle firing patterns were found in subjects with ankle hypermobility.(12)
Therapeutic
exercise is one of the must important interventions used by rehabilitation
professionals. Physiotherapists routinely prescribe hip abduction strengthening
exercises for patients who have sustained Hip injury or others who have
undergone total hip arthroplasty.(13)
Physiotherapists
use many variations of hip abductor strengthening exercises in the rehabilitation
process. Many clinicians use a standard side lying hip abduction exercise.(11,14,15) Other common methods of strengthening hip abductor muscles
include weight bearing exercises (13) such as pelvic drop, weight bearing
hip abduction and weight bearing with flexion abduction of contra lateral
hip and non weight bearing exercises (13) such as side lying hip abduction,
non weight bearing standing hip abduction and non weight bearing standing
flexed hip abduction.
Many
clinicians usually concentrate on hip abductor strengthening by open
kinematic chain exercises. This study focuses on strength improvements
of Hip abductor muscles over stable and unstable platform. Till now
no randomized clinical trial was done to find the effectiveness of hip
abductor strengthening using dynamic platform. So this study intends
to compare the effect of weight bearing hip abduction exercise on a
stable platform and dynamic platform lateral step-up in improving the
strength of hip abductors.
Subjects:
Prior
to participation in the study, the subjects were explained in detail
about the testing procedures and associated risks and benefits specific
to the study and they acknowledged their participation by signing an
informed consent. The subjects were then randomly divided into
2 treatment groups, dynamic platform (wobble board) (DP) or stable platform
(SP). Randomization was performed by using sealed envelope containing
a slip of paper indicating group assignment as either DP or SP.
The subjects were assigned a number and recorded on all data collection
forms and were blinded from the assessor. Subjects with no lower
extremity dysfunction and who can safely perform a single leg stance
on each lower extremity were included in the study. Females and
individuals with history of significant lower extremity injury or surgery
of lower extremity in the preceding year, acute illness, residual pain
or disability, Cardio vascular symptoms, neuromuscular diseases and
conditions in which strength testing is contra-indicated were excluded
from the study. The study was approved by Institutional Review Board.
Procedure:
The
tester is a senior physiotherapist with more than 10 years of clinical
experience and had evaluated the strength of more than 800 patients
using dynamometers. The tester was blinded to the subject’s group
allocation and the strength of the subjects was recorded on a form using
the serial number of the subjects and were stored in a secure place.
The post test values were also tested in the same fashion and the data
were later utilized by the authors for analysis. Baseline Hydraulic
Hand-Held Dynamometer (FEI, Irvington, NY) was used in the study.
The dynamometer was calibrated by the manufacturer prior to the study
and was also checked by using known weights. The hand-held dynamometers
are found to have good test-retest reliability (16,17) and can be used
for measuring the hip abduction strength.(18,19) The test- retest reliability
of hand held dynamometer muscle testing in the lower extremity is good
with interclass correlation coefficient (ICC) of 0.68 to 0.79, (20)
0.95 to 0.99 (21) and 0.84 to 0.91.(22) Subjects were tested in a gravity
minimized supine position with a hand-held Dynamometer attached to a
stationary device stabilized at the side of examination couch. This
type of anchoring station has been found to be highly reliable in the
measurement of hip girdle strength and has been used in previous studies.
(18,23) A study on reliability of dynamometer attached on to anchoring
station reported a ICC of 0.94 to 0.98 for hip abductor and extensor
strength testing.(24) Soft foam was placed on the handle of the Hand
Held Dynamometer to provide comfort to the subjects during the participation.
(24) Right lower extremity was chosen for evaluation and data collection
for all subjects. Subjects were positioned so that the dynamometer was
5 cm proximal to the lateral femoral condyle (knee joint line) of the
right limb.(23) The same placement was used for every subject during
pre and post-tests.
To
stabilize the pelvis, a belt was placed across the participant’s anterior
superior iliac spines and around the table during the testing procedure.
(18,23) Care was taken not to allow the subjects to rotate the pelvis
or perform internal rotation, external rotation or flexion at the hip.
Use of upper extremities to stabilize the trunk was permitted. Maximum
effort was used to perform a “Make Test” (13,16) in which subject
exerted a maximal isometric force against the dynamometer for five seconds
on each of the pre-test and post-test. Proper explanations were given
by the tester. The subjects received two practice sessions. The
strength measurements were recorded the next day. Three trials
were taken. Rests of two minutes were given between the trials
to avoid fatigue.
Intervention:
In
dynamic platform (wobble board) lateral step-up group (DP), subjects
stood with both lower extremities shoulder width apart then they performed
a lateral step-up on the centre of a 20” wobble board (height of the
half sphere beneath the board is one and half inch) and maintained the
pelvis in level. Balancing on the wobble board the subjects were
instructed to lift the contra lateral lower extremity from the ground
and abducts the leg up to 25˚.(13) Then the subject returns back to
starting position and repeats the exercise for 15 repetitions over 3
sets. In stable platform lateral step-up weight bearing standing
exercise group (SP), the subjects did a lateral step up on a 11 cm platform
on their right lower extremity and maintained the pelvis in level and
then were instructed to lift the contra lateral extremity from the ground
and to abduct to 25˚.(7,13)
In
the both procedures, the subjects returned back to their starting position
and repeated the exercise for 15 counts over 3 sets. Approximately
3% of body mass was added above the ankle on the contra lateral side
(13) for enhancing ipsilateral hip abductor recruitment.(7,13) The
subjects practiced their respective exercise to familiarize themselves
with task until they demonstrated proficiency. Subjects generally required
8 to 10 practice repetitions for respective exercise. The frequency
of exercises was three sessions a week for six weeks.
The
subjects were asked not to indulge in any sports activity or other exercise
program during the duration of the study. At the end of the sixth week
the post-test dynamometric values were collected.
Statistical
Analysis:
Prior
to data analysis, strength measurements, recorded in kg, were normalized
to body weight for each subject. Statistical analyses were done
using Statistical Package for Social sciences, Version 17 for windows
(SPSS-17). Changes within the group if any significant were analyzed
using paired t-test and the differences between the groups were analyzed
by independent t-test. The alpha level for all analyses was set at .05.
A
total of 110 subjects were screened for the study (Figure-1).
Forty five of these were excluded due to the following reasons: 26 did
not meet the inclusion criteria and 19 were not interested to participate.
Sixty five subjects were then randomly assigned to receive Wobble board
lateral step-up exercise (n=33) or Stable Platform Lateral step-up standing
exercise group (n= 32). Of the 65 subjects, three subjects were
not evaluable (1 subject in DP group and 2 subjects in SP group).
Two subjects one in each group were not interested in continuing the
exercises and one subject in SP group was lost as he moved out of the
city. The analyses was made using the remaining subjects of DP
group (n=32) and SP group (n=30). All the 65 subjects were men,
and the mean (SD) age was 21.08 (1.65) years. Table 1 summarizes
their baseline characteristics (age, body weight and hip abductor muscle
strength)
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Figure-1.
CONSORT 2010 Flow Diagram of randomized clinical trial: number
of participants screened, randomized, and retained and analyses. |
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Table-1:
Baseline demographics, Body weight and Outcome measure of participants |
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Variable |
Dynamic platform lateral step-up
exercise group (DP) n=33 |
Stable Platform Lateral step-up
exercise group (SP) n=32 |
t |
p |
| Age |
21.12 (1.63) |
21.03 (1.69) |
.492 |
.624 |
| Body weight |
59.10 (3.69) |
58.66 (3.52) |
.218 |
.828 |
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Hip abductor
Muscle strength |
19.41(3.55) |
18.95 (2.29) |
.612 |
.543 |
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Table-2:
Comparison of pre and post intervention values of
DP group and SP group |
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Groups
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n |
Mean (Std. Deviation) |
t
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p
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DP_Pre
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32 |
19.47 (3.59) |
-41.080 |
.000 |
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DP_Post
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32 |
26.93 (3.19) |
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SP_Pre
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30 |
19.07 (2.32) |
-23.790 |
.000 |
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SP_Post
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30 |
22.67 (2.46) |
Analyses
of pre and post intervention data were done only for the subjects who
have completed the study. Table 2 shows the paired t test values
for both groups i.e. comparison of pre and post intervention values
of hip abductor muscle strength within group. Out of 33 subjects assigned
in DP group only 32 completed the study. The p value < 0.001
shows there is statistically significant improvement in hip abductor
muscle strength in DP group. In SP group 32 subjects were assigned and
30 have completed the study. The p value < 0.001 shows there is statistically
significant improvement in hip abductor muscle strength in SP group.
Independent t test was used to find out any significant difference in
post intervention values between the groups.
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Table-3:
Comparison of hip abductor muscle strength after intervention |
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Groups |
n |
Mean (Std. Deviation) |
t |
p |
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DP |
32 |
26.93 (3.19) |
5.858 |
.000 |
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SP |
30 |
22.67 (2.46) |
Table 3
shows the independent t test value of hip abductor muscle strength of
both groups after intervention. P value < 0.001 shows that there
is statistically significant difference between both groups after intervention
with increased strength in DP group than SP group. No adverse events
were noted during the course of the study.
This
study compared the effects of two techniques on improving hip abductor
muscle strength using dynamic platform Lateral Step-up and stable platform
lateral Step-up Exercise. Among 65 subjects 33 subjects received dynamic
platform Lateral Step-up and other 32 received the stable platform lateral
step-up exercise. Exercises are commonly used weight bearing exercises
for the lower extremity.
Nawoczenski
and Neumann have defined internal torque as the effect of a force tending
to move a body segment about a joint’s axis of rotation (25) with
its magnitude dependent on the applied external torque. In this program
the external torque produced by gravity on head, arms, trunk and contra
lateral lower extremity (approximately 84% of body mass)
contracted by internal forces of gluteus musculature.(13)
Exercise
in weight bearing generates very high torque for hip abductor muscle
than non weight bearing hip abductor exercises. Exercise program emphasizing
weight bearing and postural stability resulted in a significant improvement
in muscle strength, postural stability and self perceived function in
patients four to twelve months after total hip arthroplasty.(26) Exercises
to increase hip abduction strength is beneficial in rehabilitation of
patients with ankle sprains.(27) Hence exercise in weight bearing would
be more beneficial in gluteal muscle strengthening and rehabilitation.
Lateral
step-ups on unstable platform (wobble board) have not been described
in literature. This study focused on strength improvements due to unstable
platform lateral step-ups. In this study the group exercises with dynamic
platform (wobble board) lateral step-up improved better than stable
platform lateral step-up. This may be attributed to inducing neuromuscular
adaptations of stretch reflex, elasticity of the muscle and sensory
system of the joint. (28) Weight bearing exercises induce co-contraction
of agonist and antagonist muscle synchrony in maintaining joint stability
by increased joint compression. Wobble board lateral step-up may
have enhanced sensory motor training of the hip abductor muscle in contribution
to improved muscle performance.
The
study noted that there is significant improvement in the strength of
abductor in the both groups. This may be due to specific training of
hip abductor muscle due to body weight resistance in lateral step-up
exercises. Clinically, many studies reveal that these exercises are
very helpful in late – phase of exercise program in conditions like
total hip arthroplasty, post traumatic immobilization, ankle sprains,
iliotibial band friction syndrome, patellofemoral pain and also in training
of athletes in sporting activities, like basket ball, soccer, etc.
The
strength measurements were recorded in Kilograms instead of torque and
were normalized to body weight for each subject. Although the
subjects had similar baseline characteristics for age, sex, weight and
participation in sports and other recreational activities, no control
was exercised over the possible differences in leg length of the subjects.
Therefore, a bias could have resulted due to the difference in the moment
arm between the groups.
This
study states that exercises are effective in strengthening hip abductors
and wobble board lateral step-up exercise may be incorporated in rehabilitation
program for improving the strength of hip abductor muscle. A similar
study can be done among the females and especially geriatric population
for whom hip abductor strengthening is important following hip arthroplasty
or other degenerative joint diseases. A future study can acknowledge
the height of the subjects. A similar study is also needed to
determine the effect of other modes of hip abductor strengthening exercises.
This
present study suggests that dynamic platform lateral step-up exercise
is effective in improving the muscle strength of hip abductor than the
stable platform lateral step-up exercise.
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