Clinical Section Received: November 30, 2007 Accepted: July 8, 2008 Published online: August 27, 2009
Gerontology DOI: 10.1159/000235863
Stretching Exercise Program Improves Gait in the Elderly Fabiano Cristopoliski a José Angelo Barela b, c Neiva Leite a Neil E. Fowler d André L. Felix Rodacki a, d a
Center for Studies of Motor Control, Department of Physical Education, Federal University of Paraná, Curitiba, Laboratory of Movement Studies, Department of Physical Education, Institute of Biosciences, State University of São Paulo, Rio Claro, and c Laboratory of Movement Analysis, Center of Biological and Health Science, Cruzeiro do Sul University, São Paulo, Brazil; d Department of Exercise and Sport Science, Manchester Metropolitan University, Alsager, UK b
Key Words Physical activity ⴢ Locomotion ⴢ Stretching
Abstract Background: Ageing is characterized by a number of physical changes that contribute to a decline in the ability to perform daily tasks. Stretching has been proposed to reduce hip flexion contracture and increase hip and pelvis range of motion, thus improving gait performance. Objective: The purpose of this study was to determine whether a supervised stretching program designed to improve the range of motion of the lower limbs alters gait kinematics in older adults. Methods: Twenty healthy older adult women (65.9 8 4.2 years old and BMI 24.9 8 3.5) were divided into 2 groups. The experimental group undertook 12 sessions of stretching exercises, whereas the control group did not engage in any physical activity. Gait performance was assessed at the beginning of the experiment and after the 4-week intervention period. Results: Those in the experimental group showed increased step length, higher velocity and reduced double support time after training. In addition, participants involved in the stretching program showed greater anterior and lateral pelvis tilt and also greater rotation (p ! 0.05). Conclusions: Based on our results, we can suggest that a supervised stretching program is effective to alter a number of gait vari-
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ables. Moreover, after the stretching protocol, aged participants displayed gait parameters which were similar to those reported in young healthy adults. Therefore, stretching can be used as an effective means to improve range of motion and reverse some age-related changes that influence gait performance. Copyright © 2009 S. Karger AG, Basel
Introduction
The ageing process is marked by a gradual reduction of locomotor efficiency as a consequence of changes in several factors including strength, muscle mass and muscle-tendon unit contracture [1, 2]. These changes may alter the individual’s ability to produce and control segmental and overall movements and, consequently, influence gait performance [3–5]. Hip flexion contracture [6], induced by immobility or low levels of regular physical activity, causes a decrease in peak hip extension, increased pelvic tilt, decreased contralateral step length and speed, and therefore lower gait efficiency [7]. Some studies [8, 9] have also suggested that individuals with diminished movement of the hip joint are more prone to a fall.
André L. Felix Rodacki Departamento de Educação Física, Universidade Federal do Paraná R. Coração de Maria, 92 – BR116 km 95 – Jardim Botânico Curitiba (Brazil) Tel. +55 41 3360 4333, Fax +55 41 3360 4336, E-Mail
[email protected]
However, a decline in gait efficiency seems not be an inevitable consequence of increasing age. Positive effects of strength training programs on gait performance have been shown in a number of studies [10–12], indicating that age-related changes may be retarded or reversed to some extent. By contrast, only a few studies have analyzed the effects of stretching programs [7–9], which may reverse the hip flexion contracture noted above. To the knowledge of the authors, the only studies designed to analyze the effects of stretching on gait performance were conducted by Kerrigan and colleagues [e.g. 9]. They found only a small increase in hip extension range of motion at the end of the stretching program, which was not sufficient to produce any change in peak hip extension, pelvic tilt, step length or speed during gait. Unfortunately, the unsupervised nature of the program may have influenced the magnitude of possible changes due to the stretching protocol and prevented any possible improvements from such an intervention. In fact, King et al. [13] demonstrated that exercises performed under supervision are more effective than when practiced at home (with no supervision). Therefore, exercise execution and lack of control of adherence to the program may have influenced the outcomes of the study of Kerrigan et al. [9]. These are 2 critical aspects of any training protocol as it is difficult to control intensity (i.e. degree of stretching) or whether the stretching routines were fully performed by the participants (i.e. adherence). Thus, it is still not clear whether a stretching program designed to reduce hip joint contracture is able to reverse age-related decrements in gait parameters. Therefore, the aim of this study was to determine whether a 4-week (12-session) supervised stretching program for the lower limbs alters gait kinematics in an aged population. We hypothesized that a stretching program for the lower limbs should alter a number of gait parameters that influence the risk of a fall. Understanding these changes may help physical activity professionals to design programs that allow older individuals to improve their functional ability and fully benefit from physical activity.
Methods Subjects Twenty healthy elderly women living in the local community (close to the University) were contacted by flyers and folders and, after agreeing to participate in this study, gave their written informed consent. The study had been granted ethical approval by the Institutional Review Board. Participants were randomly as-
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signed to 1 of 2 groups. Twelve participants (aged 65.9 8 4.2 years, BMI 24.9 8 3.5) were assigned to the experimental group, while 8 participants (aged 65.4 8 2.9 years, BMI 24.7 8 1.0) were assigned to the control group. The control group initially consisted of 12 participants, but 4 were unavailable during the assessment sessions and, consequently, excluded from the study. Participants were screened by their physicians to determine their fitness to join a program of physical training. Participants were also screened for known physical problems that could influence gait performance (e.g. osteoarthritis, low back pain). Participants who had engaged in other regular physical activity during the 12 months preceding the present study were excluded. In addition, the Baecke questionnaire [14] was applied to determine the participants’ daily physical activity levels. As no differences were found between the participants’ physical activity levels, it was assumed that no bias occurred due to the randomization procedure applied to assign the participants to the groups. Static range of motion and gait performance were assessed for all participants at the beginning of the study and 4 weeks later. The participants in the experimental group attended 3 sessions per week, for 4 weeks, totaling 12 sessions of stretching exercises. The participants in the control group did not perform any specific activity in this period. Participants from both groups were requested to refrain from engaging in any physical activity program or from changing their usual physical demands during the period of the study. Gait Assessment Gait analysis to determine temporal and spatial gait characteristics was performed before and after the 4-week intervention period. Participants walked barefoot at their preferred velocity along a defined runway in the laboratory. Walking performances were videotaped using 4 digital camcorders (JVC, GR-D250) sampling at 60 Hz. Spherical markers were placed on the right side of the body (at the anterior superior iliac crest, the center of the greater trochanter, the lateral aspect of the epicondyle of the femur, the fibular malleolus, the center of the 5th metatarsophalangeal joint and over the most prominent point of the rear aspect of the calcaneus) and were digitized using specific software (Simi Motion, version 6.1). After digitizing images from all 4 cameras, 3-dimensional coordinates were recreated (direct linear transformation) and filtered using a recursive 2nd-order Butterworth filter with a cutoff frequency of 10 Hz. Figure 1 depicts a biomechanical model in which the landmarks, segments and joints are indicated. Movements of posterior tilt, extension and plantar flexion were reported as negative [5], as were leaning movements to the right side and forward rotation of the pelvis to the left side [15]. Two successive ipsilateral heel contacts were used to define 1 gait cycle, which was time-normalized (0–100%). After this procedure, the ensemble average of the right segment from 3 gait cycles of each participant was calculated and the following spatial and temporal gait variables were determined: cycle duration (seconds); swing phase duration (seconds); stance phase duration (seconds); double stance duration (seconds); step length (meters); gait velocity (meters/second); heel contact velocity (meters/second); pelvic anterior leaning (degrees); pelvic lateral tilt (degrees); pelvic rotation (degrees); hip joint range of movement (degrees); knee range of movement (degrees); ankle range of movement (degrees), and toe clearance (meters).
Cristopoliski /Barela /Leite /Fowler / Rodacki
Stretching Assessment and Training Program The static range of the hip and ankle joints was determined 4 weeks apart for all participants by photography [16]. Markers were placed at the greater trochanter, the femoral lateral epicondyle, the fibular malleolus, the 5th metatarsophalangeal joint of the right segment and the tibial malleolus of the left segment, which allowed later quantification of initial and final displacement during a gradual and slow joint manipulation. Hip extension range of motion was assessed in a prone position while the right segment was extended until the point at which no further movement was possible or a compensatory movement of the opposite segment occurred. Hip flexion range of motion was assessed using the Thomas test [9], which is a popular and straightforward procedure to quantify hip joint contracture. Ankle plantar flexion range of movement was assessed in a supine position. Participants from the experimental group undertook a 12-session training program (3 sessions per week). Before starting the stretching exercises, participants walked in the laboratory for 5 min to warm up [17]. Then participants performed the training exercises in a random order. Hip extensor muscles were stretched with the participants in the dorsal position while the experimenter flexed the joint. Hip flexor muscles were stretched with the participant in a lateral lying position with the segment closer to the ground flexed at 90° at the hip level, while the ipsilateral segment was driven by the experimenter into hyperextension at the hip joint and flexion at the knee joint. Ankle plantar flexor muscles were stretched with the participant in a supine posture by a dorsiflexion action of the experimenter with the thigh raised at 45°. All stretching exercises were performed 4 times and held for 60 s each time [18, 19] (i.e. a total of 240 s for each segment). Exercises were alternated between segments and were held in the position at which participants reported initial discomfort. The interval between each exercise was not controlled but was sufficient to position the participant for the next exercise. Static exercises were chosen because they have been described as the most appropriate for elderly people [20] and are commonly employed in this population [6]. Statistical Analyses After confirming data normality and homogeneity, multivariate analyses of variance with group (experimental and control) and testing time point (before and after training) as factors were conducted, with the last factor treated as a repeated measure. Dependent variables for the multivariate analyses of variance are presented in tables 1–4. Univariate analyses and post hoc Scheffé tests were applied when necessary. Statistical analyses were performed using the Statistica쏐 software (Statsoft Inc., version 5.5) and the alpha level was set at 0.05.
Fig. 1. Representation of the anatomical landmarks (top), joints (middle) and movement convention (bottom) used to determine the gait variables in both conditions (before and after the stretching program). ASIC = Anterior superior iliac crest (L = left; R = right); TROC = the most prominent protuberance of the greater trochanter; LAEF = lateral aspect of the epicondyle of the femur; MALE = fibular malleolus; META = center of the 5th metatarsophalangeal joint; CALC = the most prominent point of the rear aspect of the calcaneus; LPT = lateral pelvic tilt; APT = anterior pelvic tilt.
Results
Physical activity level, measured using the Baecke questionnaire, did not differ between the experimental (6.2 8 0.4) and control (6.0 8 0.3) groups (p 1 0.05), both of which were deemed moderately active. Static range of motion increased in both hip and ankle joints for the experimental group after the stretching program, whereas
for the control group it remained unchanged. The stretching training program also resulted in changes in the Thomas test, in which uni- and biarticular hip flexor muscles showed significantly improved results. Table 1 depicts the flexibility results for both experimental and control groups.
Stretching Improves Gait
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Table 1. Mean 8 SD values for the flexibility tests performed before and after the stretching program
Group
Variable
Before
After
Mean variation %
Experimental
hip extension hip uniarticular flexors hip biarticular flexors plantar flexor amplitude
73.087.9 6.382.1 7.084.7 39.685.4
91.987.0 2.081.3 2.782.7 48.784.0
+25.0* –66.7* –66.1* +17.5*
Control
hip extension hip uniarticular flexors hip biarticular flexors plantar flexor amplitude
67.583.7 5.181.6 7.182.8 43.086.2
67.984.5 2.081.3 7.582.5 42.787.4
+0.3 –2.0 –5.6 +0.8
Values shown are degrees. * Significant differences between groups after training. Variation represents percentage with respect to the pre-test values.
Table 2. Mean 8 SD values of temporal variables before and after the stretching program
Group
Variable
Before
After
Experimental CD, s STD, % SWD, % DSD, s
1.1080.13 65.383.3 34.783.3 0.3380.06
1.0580.08 –5.0* 61.581.8 –5.9* 38.581.8 +11.2* 0.2580.05 –22.3*
Control
1.0780.04 66.982.0 33.182.0 0.3280.02
1.0780.08 66.082.8 34.082.8 0.3280.01
CD, s STD, % SWD, % DSD, s
Mean variation %
+0.7 –1.4 –2.8 –0.7
CD = Cycle duration; STD = stance phase duration; SWD = swing phase duration; DSD = double support phase duration. * Significant differences between groups after training. Variation represents percentage with respect to the pre-test values.
Spatiotemporal Variables Participants from the experimental group also walked with greater step length and higher velocity after the stretching exercises, whereas no difference was observed for the control group participants. No differences were observed for the other variables when comparing testing time points and groups. Table 3 shows the spatiotemporal variables. Angular Variables Table 4 shows the angular variables for both experimental and control groups. The experimental group participants showed greater anterior and lateral pelvis tilt and also greater pelvis rotation. No differences were observed for the control group participants between the testing time points. No differences were observed between the groups with regard to the range of joint motion.
Discussion
Temporal Variables There was no change in cycle duration either between the groups or the testing time points. However, participants in the experimental group had reduced relative stance phase duration and increased relative swing phase duration. Finally, participants in the experimental group showed reduced double support phase duration when compared to the control group. Table 2 shows the gait temporal variables.
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The aim of the present study was to examine the effects of a stretching program involving the hip flexor and extensor muscles and ankle plantar flexor muscles on the gait of aged individuals. The results showed that the stretching program was efficient at increasing both hip and ankle range of motion for those participants in the experimental group compared to those in the control group. This improved range of motion resulted in a faster gait with increased step length and shorter double support duration. The stretching training program also proCristopoliski /Barela /Leite /Fowler / Rodacki
duced changes in the pelvis motion during the gait cycle. In general, the stretching program was seen to produce a reduced tightness of the tissues surrounding the hip and pelvis [9]. The effectiveness of the stretching program in our aged participants is also demonstrated by the similarity in the range of motion of the hip extensor muscles at the end of the training period with the normative data reported for young healthy adults (91.3 8 7.0° [21]). In addition, the average gain in the range of movement was greater than that presented in other studies [18, 19, 22] and reinforces the idea that the stretching protocol undertaken by our aged participants was sufficient and effective to cause important changes in the joint range of motion. After the stretching protocol, step length and velocity not only improved but also assumed values that resemble those generally found in younger adults [23, 24]. Walking velocity has been one of the most widely used variables to examine gait pattern in elderly adults [4, 25] as well as in populations with specific motor impairments, such as hemiparetics [26]. Therefore, the improvements in gait performance shown in this aged population following a stretching program suggest that stretching (i.e. reducing hip joint tightness) is an effective strategy to reverse changes in some gait parameters related to the ageing process. On the other hand, participants in the control group showed no changes in the selected parameters. The similarity of the results observed in the control group is a strong indication that the changes were a consequence of the training effect. The gait pattern displayed after the stretching program not only indicates an improvement in behavioral performance but also in terms of stability. In general, aged individuals tend to modify the temporal organization of walking in an attempt to improve stability, where reduced swing phase duration and increased stance phase duration are found [3, 27]. In addition, double stance duration is also reported to increase as a strategy to improve dynamic stability [4, 23, 28]. The stretching program was successful not only in improving important gait characteristics but also in influencing these variables; changes in these variables were partially reversed, and this then presented a pattern compatible to that reported in healthy young adults [23, 24]. The most important changes induced by the stretching protocol occurred around the pelvis, which plays an important role in movement control of the lower limbs. The peak anterior tilt of the pelvis has been described as being closely related to the risk of falling as it projects the Stretching Improves Gait
Table 3. Mean 8 SD values of spatiotemporal variables before
and after the stretching program Group
Variable
Before
After
Experimental STL, m GVE, m/s HPAV, m/s CLE, cm
1.1680.08 1.0780.17 0.8380.23 1.5580.59
1.2680.07 +8.6* 1.2280.13 +13.9* 0.8180.12 –3.5 1.9780.59 +27.1
Control
1.1280.05 1.0680.07 0.8880.18 1.5380.60
1.1280.13 1.0680.09 0.9080.26 1.4880.37
STL, m GVE, m/s HPAV, m/s CLE, cm
Mean variation %
0.0 +0.1 +2.3 –3.4
STL = Step length; GVE = gait velocity; HAPV = heel anteriorposterior velocity; CLE = toe clearance at midswing phase. * Significant differences between groups after training. Variation represents percentage with respect to the pre-test values.
Table 4. Mean 8 SD values of angular variables before and after
the stretching program Group
Variable
Before
After
Mean variation %
Experimental
APT LPT PRO HRM KRM ARM
9.380.7 6.380.7 11.382.0 29.883.8 53.285.5 29.083.2
6.081.4 8.481.5 15.383.4 28.583.5 55.286.2 29.683.1
–35.8* +33.8* +35.4* –4.4 +3.8 +2.1
Control
APT LPT PRO HRM KRM ARM
9.680.6 6.781.8 10.882.4 29.983.2 53.784.0 27.883.6
9.481.1 6.782.1 10.782.9 29.783.4 53.885.5 27.883.1
–1.8 +0.1 –1.2 –0.7 +0.2 –0.1
Values shown are degrees. APT = Anterior pelvic tilt; LPT = lateral pelvic tilt; PRO = pelvic rotation; HRM = hip range of motion; KRM = knee range of motion; ARM = ankle range of motion. * Significant differences between groups after training. Variation represents percentage with respect to the pre-test values.
center of mass forwards during walking and increases instability [5, 9, 23]. Thus, pelvic retroversion can be interpreted as a positive effect of stretching training and can be attributed to a reduction in the tension provoked by the tightness of tissues around the hip flexor muscles Gerontology
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that restricted joint extension and caused an anterior inclination of the pelvis [8, 9, 23]. The results of the present study did not confirm the results of Kerrigan et al. [9] who were not able to show a significant reduction of the peak anterior pelvic inclination after a 10-week period of training. Possibly, the lack of rigorous control of participants’ adherence to the training program may have compromised the results of their study, as indicated by the authors [9]. In fact, unsupervised programs tend to be less effective than programs closely monitored by qualified professionals [13]. Lateral tilt and pelvic rotation are important components of the pelvic step that influence and determine the step length and displacement velocity [8, 29]. Greater rotation and lateral tilt of the pelvis allow the heel of the swinging leg to be positioned further than usual with respect to the support limb [15]. After the stretching program, pelvic tilt and rotation in our participants were similar to those reported for younger individuals [24]. The changes observed around the pelvis may be the effect of a reduced moment around the segment as a result of diminished passive resistance offered by the muscles that restrict extension (e.g. the iliopsoas muscle and rectus femoris) and flexion (e.g. hamstrings) movements [9, 23]. Similar joint ranges of movement around the hip, knee and ankle during walking revealed no effect derived from stretching training. It can be speculated that changes around the pelvis may have minimized changes around the other joints of the lower limb. Our results indicated that the stretching training program induced changes around the pelvis in a more pronounced way than it did changes in other joints of the lower limbs during gait performance. In fact, control of the pelvis plays an important role in the dynamics of the lower limbs as the muscles spanning this joint are responsible for trunk stabilization and limb control. One possibility is that reducing the stiffness of the muscles of the pelvis may have allowed
participants to better control movement dynamics. Changes in the variables selected to describe pelvic behavior, also known as the gait determinants [30], have been proven to reduce height variations of displacement of the center of mass and consequently to improve gait performance and reduce energetic demand [30, 31]. This demonstrates the importance of targeting exercise programs to these critical muscles if improved gait is the desired outcome. Other studies which have analyzed the effects of chronic stretching failed to detect significant changes in response to such training [9, 32], possibly as a consequence of a failure to target and influence the key pelvic musculature or due to participants’ poor compliance with the program. On the other hand, a study designed to determine the acute effects of stretching, i.e. effects of a single training session [33], showed results comparable to those of the present study. Thus, the important changes in gait characteristics observed after a single stretching session can also be achieved with a stretching program involving many sessions when closely monitored and conducted. The present study has some limitations that are important to bear in mind, such as the fact that the control group did not undertake any physical activity and may have had different motivation in comparison to their counterparts in the experimental group. In addition, our participants were aged around 65 years, and adults over this age tend to experience a greater reduction in hip range of motion, and their response to a stretching protocol might differ from that of our participants. Finally, it is not known if there is a ‘ceiling effect’ above which increases in peak hip extension exert no influence on gait performance. Future studies using different walking speeds may provide more insight into how different changes in joint range of motion influence gait-related parameters.
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