The effect of duration of stretching hamstring muscles, Artykuły, badania naukowe
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The Effect of Duration of Stretching
of the Hamstring Muscle Group for
Increasing Range of Motion in
People Aged 65 Years or Older
65
years of age) have not been studied to determine the effectiveness of
increasing range of motion (ROM). The purpose of this study was to
determine which of 3 durations of stretches would produce and
maintain the greatest gains in knee extension ROM with the femur
held at 90 degrees of hip flexion in a group of elderly individuals.
Subjects.
Sixty-two subjects (mean age
$
5
65–97) with tight hamstring muscles (defined as the inability to extend
the knee to less than 20° of knee flexion) participated. Subjects were
recruited from a retirement housing complex and were independent
in activities of daily living.
Methods.
Subjects were randomly assigned
to 1 of 4 groups and completed a physical activity questionnaire. The
subjects in group 1 (n
5
84.7 years, SD
5
5.6, range
5
70 –97), a control group, performed no stretching. The randomly
selected right or left limb of subjects in group 2 (n
5
13, mean age
5
85.1 years, SD
5
6.4, range
5
17, mean
age
5
85.5 years, SD
5
4.5, range
5
80 –93), group 3 (n
5
15, mean
age
5
85.2 years, SD
5
6.5, range
5
65–92), and group 4 (n
5
17, mean
68 –90) was stretched 5 times per
week for 6 weeks for 15, 30, and 60 seconds, respectively. Range of
motion was measured once a week for 10 weeks to determine the
treatment and residual effects. Data were analyzed using a growth
curve model.
Results.
A 60-second stretch produced a greater rate of
gains in ROM (60-second stretch
5
83.2 years, SD
5
4.6, range
5
5
2.4° per week, 30-second
0.6° per week), which
persisted longer than the gains in any other group (group 4 still had
5.4° more ROM 4 weeks after treatment than at pretest as compared
with 0.7° and 0.8° for groups 2 and 3, respectively).
Discussion and
Conclusion.
Longer hold times during stretching of the hamstring
muscles resulted in a greater rate of gains in ROM and a more
sustained increase in ROM in elderly subjects. These results may differ
from those of studies performed with younger populations because of
age-related physiologic changes. [Feland JB, Myrer JW, Schulthies SS,
et al. The effect of duration of stretching of the hamstring muscle
group for increasing range of motion in people aged 65 years or older.
Phys Ther.
2001;81:1100 –1117.]
5
1.3° per week, 15-second stretch
5
APTA is a sponsor of the
Decade, an international,
multidisciplinary initiative
to improve health-related
quality of life for people with
musculoskeletal disorders.
Key Words:
Age, Elderly, Flexibility, Hamstring muscles, Lower extremity.
J Brent Feland
J William Myrer
Shane S Schulthies
Gill W Fellingham
Gary W Measom
1110
Physical Therapy . Volume 81 . Number 5 . May 2001
Background and Purpose.
Stretching protocols for elderly people (
age
stretch
stretching techniques to determine which
technique is most effective for increasing
joint range of motion (ROM).
1–5
Stretching
is important because it is believed to provide many
physical benefits, including improved flexibility,
3,6,7
improved muscle or athletic performance,
8,9
improved
running economy (decreased energy expenditure at a
given speed),
10,11
injury prevention,
3,11
promotion of
healing, and possibly decreased delayed-onset muscle
soreness.
12,13
Although evidence to support these beliefs
is limited, stretching appears to us to be in widespread
use.
Physiologic changes that are said to occur with age
include muscle atrophy
19
; reduced capacity for healing,
diminished capillary blood supply, and reduced
amounts of mesenchymal stem cells
20
; and loss of
strength and elasticity in soft-tissue matrices.
20
Increased
muscle and joint stiffness with increased amounts of
fibrous connective tissue
11,21
has also been reported.
It is our opinion, based on the review of the literature,
that connective tissue compliance appears to be a major
factor in musculoskeletal flexibility. Plastic rather than
elastic deformation, theoretically, can result in more
permanent lengthening of the tissues.
22
Plastic changes
to connective tissue are thought to be brought about by
slow, low-intensity, and long-duration stretches that do
not injure the muscle.
1,23
Some authors
6,17,24
have sug-
gested stretch durations of 15 to 30 seconds using either
proprioceptive neuromuscular facilitation (PNF) tech-
niques or other stretching methods, whereas Smith,
3
based on a review of the literature, suggested that the
stretch should be held for 15 to 20 seconds.
Researchers have looked at the effect of different vari-
ables associated with stretching, including force or inten-
sity,
14
position,
15
frequency and duration,
6,16,17
and
repetition.
18
In the majority of these studies, younger
people, usually between the ages of 18 and 39 years, were
the subjects. The results of these studies, therefore, may
not be applicable to all age groups, particularly elderly
people because of age-related physiological changes.
JB Feland, PT, PhD, is Assistant Professor, Department of Physical Education, College of Health and Human Performance, Brigham Young
University, RB 120A, Provo, UT 84602 (USA) (Brent_Feland@byu.edu). Address all correspondence to Dr Feland.
JW Myrer, PhD, is Associate Professor, Department of Physical Education, College of Health and Human Performance, Brigham Young University.
SS Schulthies, PT, PhD, ATC, is Associate Professor, Department of Physical Education, College of Health and Human Performance, Brigham
Young University.
GW Fellingham, PhD, is Associate Professor, Department of Statistics, Brigham Young University.
GW Measom, PhD, APRN, is Associate Professor, Department of Nursing, Brigham Young University.
Dr Feland, Dr Myrer, Dr Schulthies, and Dr Fellingham provided concept/research design. Dr Feland, Dr Myrer, and Dr Schulthies provided
writing. Dr Feland provided data collection, project management, fund procurement, and facilities/equipment. Dr Fellingham provided data
analysis. All authors provided consultation (including review of manuscript before submission. The authors thank Jason Adams, Jody Alley,
Rebecca Jo Langford, AnnMarie Linnett, Eric Lowe, and Adam Turley for their assistance in the data collection process.
This study was approved by the Institutional Review Board at Brigham Young University.
This article was submitted December 10, 1999, and was accepted October 24, 2000.
Physical Therapy . Volume 81 . Number 5 . May 2001
Feland et al . 1111
N
umerous researchers have compared various
For our study, a
“long-duration” stretch
was defined as a
stretch of greater than 30 seconds’ duration for one
repetition, and a
“low-intensity” stretch
was defined as a
stretch based on each subject’s perception of the onset
of discomfort in the back of the thigh. Low-intensity and
long-duration stretching approaches may optimize
increases in ROM among elderly people due to the
amount of connective tissue, increased stiffness, and
decreased elasticity that can occur with the aging process.
other subject moved away). Fifty-six subjects (12 male, 44
female) continued through the 4-week recovery period
(out of the 4 subjects who dropped out during the
recovery period, 3 subjects developed other health prob-
lems and 1 subject moved to another residence).
Instrumentation
A double-arm (30.5-cm [12-in]) clear plastic goniometer
was used to measure knee extension ROM. Prior to data
collection, we performed a pilot study to establish intra-
tester reliability of measurements of knee extension
ROM. A test-retest design was used on 14 subjects of
similar age (
Although various researchers have investigated the
effects of exercise on ROM
13,25–27
and joint stiffness
28
in
elderly people, the optimal duration of a stretch of the
hamstring muscles to improve knee extension ROM has
not been determined.
65 years), with measurements taken 1
week apart by the research assistant who would perform
all measurements throughout the study. Reliability was
determined using an intraclass correlation coefficient
(ICC [3,1]). An ICC of .96 was considered appropriate
for continuing the study.
Therefore, the purpose of our study was to compare the
effects of 6 weeks of repeated stretching of the hamstring
muscle group for 15, 30, or 60 seconds to determine
whether a longer stretch duration enhances ROM gains
among elderly people.
Experimental Procedure
Method
Measurementprotocol.
Choice of which lower extremity
to use for the stretching protocols was determined by the
toss of a coin for each subject; tails represented the left
lower extremity, and heads represented the right lower
extremity. Each subject was then measured for knee
extension ROM on both lower extremities. Measure-
ment of knee extension ROM was made with the subject
lying supine with the opposite lower extremity extended
and the lower extremity being measured positioned at
90 degrees of hip flexion. The greater trochanter and
the lateral epicondyle of the femur and lateral malleolus
were palpated and served as landmarks during measure-
ment, as outlined by Norkin and White.
29
We attempted
to maintain hip flexion at 90 degrees while the research
assistant moved the tibia into the terminal position of
knee extension, which was defined as the point at which
the subject reported feeling discomfort. The goniomet-
ric value was then recorded. The measurement recorded
was the angle between the leg position and full knee
extension (considered to be 0°) (Fig. 1). Because knee
joint contractures were ruled out, the measurement of
knee extension ROM was considered to be an indirect
measure of hamstring muscle flexibility, with hamstring
muscle tightness being the purported cause of a lack of
knee extension ROM.
Subjects
Subjects recruited for this study were independently
living in a retirement housing complex and were
informed of the purpose of the study and the need for
volunteers through a community meeting at the retire-
ment facility. Of the 78 subjects who volunteered for the
study, 62 subjects (mean age
5
84.7 years, SD
5
5.6,
65–97) qualified by not having any hip or knee
replacements or any history of pathology in the low back,
hips, or knees for the 3 months prior to the study.
Subjects voluntarily participated and signed an informed
consent form approved by Brigham Young University,
Provo, Utah.
To further qualify for the study, subjects had to demon-
strate “tight” hamstring muscles, defined as inability to
extend the knee to less than 20 degrees of knee flexion
with the femur held at 90 degrees of hip flexion while
the person was positioned supine. Subjects were also
screened to rule out knee joint flexion contractures by
checking knee extension ROM, as described by Norkin
and White,
29
while they were lying in a prone position. A
questionnaire was administered to all qualified subjects
in order to quantify physical activity levels. This physical
activity questionnaire has been shown to generate valid
and reliable classification scores for activity in a group of
elderly subjects who were similar, but not identical, to
ours.
30
Subjects were asked to maintain their level of
activity throughout the study. Sixty subjects (14 male,
46 female) completed the treatment portion of the study
(2 subjects did not complete the stretching phase of the
study because 1 subject voluntarily withdrew and the
All subjects were measured on the same day and at the
same time each week, before they had stretching for that
day. Measurements were taken on the stretched lower
extremity once a week for 6 weeks during the treatment
period and for 4 weeks posttreatment (recovery) to
determine the residual effect of the stretching. The
research assistant who performed the measurements was
unaware of group assignment.
1112 . Feland et al
Physical Therapy . Volume 81 . Number 5 . May 2001
$
range
5
Figure 1.
Measurement of knee extension range of motion using a goniometer.
Figure 2.
Stretching of subject’s hamstring muscles using straight-leg-raising
method.
Group assignment.
After the initial measurements, the
subjects were randomly assigned to 1 of 4 groups.
Subjects assigned to group 1 (3 men, 10 women; mean
age
85.1 years, SD
5
6.4, range
5
forth from knee to chest to lower-extremity extension in
order to prevent what has been called “thixotropic
stiffening.”
31,32
80 –93)
received a passive static stretch that was sustained for 15
seconds. Group 3 (4 men, 11 women; mean age
5
85.5 years, SD
5
4.5, range
5
Subjects in groups 2 through 4 had stretching 5 days per
week for 6 weeks. All subjects whose lower extremity was
stretched were retested for knee extension ROM every
week. A ROM measurement was also made at the end of
the 6-week treatment on the uninvolved lower extremity
to determine whether a stretching program indirectly
affected contralateral flexibility.
5
85.2
65–92) received a passive static
stretch that was sustained for 30 seconds. Group 4
(5 men, 12 women; mean age
5
6.5, range
5
5
83.2 years, SD
5
4.6,
68 –90) received a passive static stretch that was
sustained for 60 seconds.
5
Stretching procedure.
Stretching of the hamstring mus-
cles was performed by the primary researcher and 5
other research assistants (seniors in sports medicine and
exercise science). A straight-leg-raising technique was
used for this stretch because we believe that it is com-
monly used in the clinical setting for elderly people. All
subjects were supine lying as flat as possible. Due to
age-related changes in the upper thoracic and cervical
spine, we used a pillow to help maintain a comfortable
position for subjects who complained of neck pain when
trying to lie flat. Subjects who required a pillow (ie, for
both stretching and measurement) always used a pillow.
Based on the primary researcher’s observations, each
subject’s knee was maintained in extension with the
ankle at 90 degrees without medial (internal) or lateral
(external) rotation of the lower extremity, and the
extremity was raised until the subject reported discom-
fort (Fig. 2). The subject was asked to relax the lower
extremity in an effort to prevent contracting muscles
from affecting the stretch and to allow for a slow stretch.
No warm-up was allowed prior to stretching.
All research assistants were trained in administering the
stretching protocol by practicing on a similar-aged vol-
unteer who was not participating in the study due to time
constraints. Instructions included the use of the same
verbal cues to minimize variation in administration. All
stretching sessions were documented to record whether
the subjects received stretching, and assistants were
randomly assigned each day to subjects in order to
reduce the risk of interaction between treatment and
assistant.
If a subject missed a scheduled session, he or she made
up the session on another day during the same week; this
occurred a total of 16 times throughout the stretching
period of 6 weeks (once for 10 subjects and twice for 3
subjects). Prior to treatment, the researchers decided
that if any subject missed more than 4 days without
stretching, the subject would be eliminated from the
study. No subject missed more than 2 “stretch days”
throughout the 6-week treatment program.
Data Analysis
Because we were primarily interested in changes occur-
ring over time, it seemed reasonable to analyze the data
using linear growth curves. The slope of a line represents
a rate of change, and different slopes in different
treatment conditions (treatment and recovery) would
Subjects in groups 2 through 4 received 4 stretches for
their designated time period, with a 10-second rest
between stretches. During the 10-second rest, each sub-
ject was asked to move the lower extremity back and
Physical Therapy . Volume 81 . Number 5 . May 2001
Feland et al . 1113
70 –97) served as the
control and received no stretching. Group 2 (3 men, 14
women; mean age
5
years, SD
range
Table 1.
Intercepts and Slopes for 6-Week Stretching Period
Treatment
Value
Standard Error
Comparison
a
Intercept
Control (no stretch)
40.98710
2.95079
m (t
5
2.72, df
5
21)
Intercept
15-s stretch
45.43737
2.72627
Intercept
30-s stretch
46.11647
3.03633
Intercept
60-s stretch
48.55765
2.80192
j (t
5
2.72, df
5
21)
Slope
Control (no stretch)
0.40292
0.32234
x (control vs 15-s stretch; t
52
2.41, df
5
390)
(control vs 30-s stretch; t
52
3.85, df
5
390)
(control vs 60-s stretch; t
52
6.58, df
5
390)
Slope
15-s stretch
2
0.61078
0.27082
a (t
52
2.26, df
5
390)
j (t
52
2.41, df
5
390)
m t
5
4.59, df
5
390)
Slope
30-s stretch
2
1.28831
0.29843
a (t
52
4.32, df
5
390)
j (t
52
3.85, df
5
390)
m t
5
2.68, df
5
390)
Slope
60-s stretch
2
2.36798
0.27082
390)
x (60-s stretch vs control; t
52
8.74, df
5
52
6.58; df
5
390)
(60-s stretch vs 15-s stretch; t
5
4.59, df
5
390)
(60-s stretch vs 30-s stretch; t
5
2.68, df
5
390)
a
a
significantly different from 0 (
P
,
.05), j
5
significantly different from control (
P
,
.05), m
5
significantly different from 60-second treatment (
P
,
.05),
x
5
significantly different from all other groups (
P
,
.05).
account for the within-subject covari-
ance structure. An autoregressive lag 1
(AR[1]) structure was found to most
closely fit the data, not unusual when
measurements are taken at equally
spaced time points. The problems
with the more traditional repeated-
measures analysis of variance in this
setting have been well documented.
34
Figure 3.
Fitted line graph of intercepts and slopes for the 6-week treatment (stretching) and 4-week
recovery period. Note: the lines do not match-up at the 6-week point because they are fitted-plot
lines that represent 2 different periods of time for each group. Group 1 was a control (no
stretching) group, group 2 had 15-second stretches, group 3 had 30-second stretches, and
group 4 had 60-second stretches.
The SAS General Linear Models Proce-
dure was used for analysis of contralat-
eral lower-extremity values and for
comparison of pretest and 4-week post-
test values for all groups. A
post hoc
Student-Newman-Keuls test was used to
compare the pretest values with the
4-week posttest values to determine
whether a difference existed between
groups when both the treatment and
recovery periods were included.
Results
A comparison of intercepts and slopes
among all groups for the treatment
period is shown in Table 1. Plots of
response functions for all 4 groups in
both treatment and recovery conditions are shown in
Figure 3. The intercepts are model-adjusted estimates of
initial ROM means for each group. There was no differ-
ence in the starting intercept (pretest) among group 1
(41°), group 2 (45°), and group 3 (46°), but there was a
indicate different rates of impact of the various treat-
ments. To implement such an analysis, the SAS (version
6.12) MIXED Procedure
33
was used to analyze the data
from treatment and recovery period times. With multi-
ple measures per subject, it is important to appropriately
1114 . Feland et al
Physical Therapy . Volume 81 . Number 5 . May 2001
a (t
5
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