The Effects of Two Stretching Procedures on Hip

The Effects of Two Stretching Procedures on Hip Range o f ~ o t i o n and Gait Economy

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JOSEPH J. GODGES, MPT,' HOLDEN MacRAE, MEd? CHARLES LONGDON,3 CHRISTINE TINBERG: PRISCILLA MacRAE, PhD4 The purpose of this study was to 1) compare two commonly practiced stretching techniques to determine which is most effective for improving hip range of motion, and 2) evaluate the effect of these techniques on gait economy. Seven asymptomatic males, 18-22 years of age, served as subjects. Goniometric measurements of hip range of motion (ROM) and gait economy, as measured by submaximal oxygen consumption of walking and running on a treadmill, were taken before and after each of the two stretching procedures, (a) static stretching, and (b) soft tissue mobilization with proprioceptive neuromuscular facilitation (STMIPNF). Static stretching procedures resulted in significant improvements in ROM for hip extension (p < 0.01) and hip flexion (p < 0.01). The STMIPNF also resulted in significant improvements in hip extension ROM (p < 0.01) and hip flexion ROM (p < 0.05). There was a significant improvement in gait economy at 40% \i02max (p c 0.05), at 60% ~ 0 m a (p x c 0.05), and at 80% ~Onmax(p < 0.01) following the static stretching procedure. The STMI PNF procedure improved gait economy only at one workload, 60% of VO~rnax(p < 0.05). These results suggest that a single bout of static stretching or STMIPNF was effective for improving hip ROM but static stretching was more effective for improving gait economy in young, asymptomatic males.

Many patients and athletes demonstrate limited movement abilities. One consequence of limited movement range is diminished efficiency when performing functional activities, such as walking (13). For example, full hip extension is required during the terminal stance phase of gait. Otherwise, compensations will occur at segments above and below the hip, such as in the lumbar spine or knee. Normal mobility of the hip requires extensibility of the periarticular structures as well as flexibility of the muscles and their fascia1 elements. There are many techniques used by therapists and trainers to improve range of motion. Questions remain, however, as to which proce-

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' Physical Therapist. 1231 Lincoln Blvd.. Suite 101. Santa Monica. CA 90401. Reprint requests should be addressed to Mr. Godges. Instructor, Department of Sports Medicine. Pepperdine University. Malibu, CA 90265. Student. Department of Sports Medicine. Pepperdine University. Malibu, CA 90265. Associate Professor, Department of Sports Medicine. Pepperdine University. Malibu, CA 90265.

0196-601 1/89/1009/0350$02.00/0 OF ORTHOPAEO~C AND SPORTS PHYSICAL THERAPY THEJOURNAL Copyright Q 1989 by The Orthopaedic and Sports Physical Therapy Sections of the American Physical Therapy Association

dures are most effective for improving flexibility and therefore joint range of motion (ROM). Several studies have examined the effects of various stretching techniques on joint ROM, but only a few have controlled 1)the stabilizationof proximal and distal articulations during the stretch and during the ROM measurements, and 2) the amount of force applied during the stretch as well as during the ROM measurements. These controlled studies have demonstrated that end-range static stretching, either alone or intermixed with muscle contractions, is effective for improving muscle flexibility and consequently joint range of motion (1, 3, 7, 8). The midrange procedures of soft tissue mobilization (STM) and proprioceptive neuromuscular facilitation (PNF) often used by physical therapists, with the goal of improving movement and function in patients with orthopaedic or neurologic disorders, have not been subjected to controlled experimental designs. One purpose of this study was to evaluate the efficacy of the midrange stretching procedures of STM and PNF, and to compare that procedure with one which utilizes end-range static stretching, to determine which procedure was more effective at improving hip range of motion. The second purpose of this study was to examine the JOSPT March 1989

effects of changes in hip range of motion on gait economy. This study examined the hypothesis that effective elongation of tight or adaptively shortened myofascia around the hip improves the agonist/antagonist balance of the hip musculature, thus promoting pelvic symmetry and economy of movement patterns (4, 10). Assessing gait economy, by measuring submaximal oxygen consumption per unit body weight required to walk or run at a given speed, tests the hypothesis that reducing muscle imbalances at the hip and pelvis by stretching shortened myofascia decreases inefficient compensations of the structures above and below the pelvis (9). METHODS


Subjects

Seven male college students (X age=20 years, X weight=75 kg, X height=l68 cm) participated in the study. All subjects actively participated in some form of physical activity as a recreational athlete; however, none participated at the intercollegiate level. All of the subjects were free of known orthopaedic dysfunction that might influence their response to 1 ) walking and running on a treadmill, and 2) connective tissue stretching procedures. The criteria for admission to this study was the presence of limitation of hip flexion and/or extension ROM (see pretest screening procedures). Hip flexion ROM was evaluated by utilizing a modified straight leg raise procedure. Hip extension ROM was evaluated by utilizing a modified Thomas Test Procedure. Both procedures will be described in detail later in the procedures section. Prior to participation in the study, all subjects read and signed an informed consent form that had been approved by the Pepperdine University Human Subjects Committee. All data were collected in the Motor Behavior and Human Performance Laboratories at Pepperdine University. All subjects completed the protocol as outlined in Table 1. Five of the subjects received the STM/PNF procedure first and then the static stretching procedure at the same time of day 1 week later. Two of the subjects received the static stretching procedure first and then the STM/PNF procedure at the same time of day 1 week later. Instructions to Subjects

The subjects were informed that their participation in the study required that they attend three laboratory sessions at the same time of day, with each session 1 week apart. The first 1/2 hour session was used to determine the subject's maximal oxygen consumption. The next two sessions (approximately 2 hours in length) included a submaximal exercise test, measurements of hip JOSPT March 1989

TABLE 1 Summary of procedures

Test day 1 Maximum oxygen consumption test using a graded treadmill protocol Seven days Test Day 2 Submaximal oxygen consumption measures of treadmill exercise at 40, 60, and 80% of the subjects ~0,max (4 minutes at three speeds for a total of 12 minutes) Ten minute rest in supine position Hip ROM measurements, both hips, flexion and extension Stretching procedure No. 1 (static stretching or STM/PNF) Hip ROM measurements, both hips, flexion and extension Submaximal oxygen consumption measures of treadmill exercise at 40, 60, and 80% of the subjects ~0,max (4 minutes at three speeds for a total of 12 minutes) Seven days Test Day 3 Submaximal oxygen consumption measures of treadmill exercise at 40. 60. and 80% of the subjects ~0,max (4 minutes at three speeds for a total of 12 minutes) Ten minute rest in supine position Hip ROM measurements, both hips, flexion and extension Stretching procedure No. 2 (static stretching or STM/PNF) Hip ROM measurements, both hips, flexion and extension Submaximal oxygen consumption measures of treadmill exercise at 40. 60, and 80% of the subjects V02max (4 minutes at three speeds for a total of 12 minutes)

range of motion, followed by one of the two stretching techniques, and then reassessment of the ROM measurements and submaximal testing. Subjects were instructed to maintain the same physical activity level over the course of their participation but not to exercise on the day of the testing. Subjects were also instructed to refrain from drinking any substance that contained caffeine on the day of testing. Pretest Screening for Shortened Hip Extensors and/or Flexors

Prospective subjects were tested for bilaterally shortened hip extensors by having them lie supine. One leg was kept in anatomical position while the other leg was passively raised with the knee in full extension until the experimenter felt the first sign of resistance. If the subjects demonstrated less than 90' of hip flexion, then they were included as subjects in the study. Prospective subjects were also tested for bilaterally shortened hip flexors. Subjects were asked to lie in a supine position with their thighs extending off the end of the table. The subject brought his knees to his chest, then released one leg, while tightly holding the other knee to his chest in order to maintain the lumbar spine flat against the table. If the released leg was short of full extension then the subject was labeled as having a shortened hip flexor and included in the study.

STRETCHING EFFECTS ON HIP ROM AND GAIT ECONOMY

351


Gait Economy Measurements

Maximal oxygen consumption (~0,max) was determined via open circuit spirometry (Vista metabolic measurement cart, Vacuumed Inc., Ventura, CA) using a graded treadmill exercise test. Subjects ran at 188-228 m/sec (7-8lh miles/ hour) to familiarize them with treadmill locomotion. Ten minutes after the familiarization run, the speed of the treadmill was set at 188-228 m/sec (depending on the subject's capabilities). The grade was increased 4% at 3 minutes, and then by 2% every 2 minutes until voluntary exhaustion. Criteria for achieving V02max were 1) increase in workload with no further increase in oxygen consumption, and 2) respiratory quotient of 1.1 or greater. Submaximal oxygen consumptionwas measured 1 week after the individual's V02max test, prior to, and following one of the two stretching procedures. Subjects ran at speeds that. elicited approximately 40, 60, and 80% of their VOnmax for 4 minutes each. The 40% of max workload elicited a brisk walk while running was elicited at the other two workloads. For all subjects, the velocity needed to elicit 40% of VOnmax was 108 m/sec (4 mph), while the velocity needed to elicit 60% of \jo2max was 161 mlsec (6 mph). However, the velocity needed to elicit 80% of ~0,max

ranged between 188-228 m/sec (7-8.5 mph) depending on the subject's capabilities. Expired gas analyzers were calibrated with gases of known concentrations prior to each maximal and submaximal test. Hip Range of Motion Measurements

To improve reliability, all measurements of hip ROM were performed by the same three investigators and each investigator performed the same task during each procedure. Numerous practice trials were performed on volunteers (not subjects) prior to beginning the study. Hip flexion ROM was evaluated using the modified straight leg raising procedure depicted in Figure 1. Bledsoe Adjustable Knee Braces (Medical Technology, Grand Prairie, TX) were placed on both extremities and locked at 0' extension. Using an indelible marker, reference lines were drawn on the lateral midline of the lower trunk and thigh. These lines were drawn parallel to the table top and served as landmarks for the goniometric measurements. The contralateral thigh was securely fixed to the table with a velcro strap. The ipsilateral leg was passively raised and a load of 15% of the subject's body weight (to the nearest l/2 kg) was applied to the leg using a pulley system with suspended weights. The force

Figure 1. Hip flexion ROM measurement.

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JOSPT March 1989


was applied at approximately 90' to the leg using an ankle cuff which was placed just proximal to the ankle. The load was applied very slowly, over 10-1 5 sec, to avoid the stretch reflex and consequent involuntary contractions by the subject's hip extensors. While the load was being applied the subject was instructed to relax and allow the weight to stretch his leg muscles. One investigator was positioned to ensure that the leg was maintained in the sagittal plane. This prevented any undesired hip abduction or adduction. The goniometric measurement was taken at the instant in which the load was fully applied. The angle between the two previously drawn lines on the trunk and the thigh was determined and this served as the hip flexion ROM measurement. If the lower extremity measured 89" or less of hip flexion ROM, the stretching procedure was applied to the hip extensors of that thigh. Hip extension ROM was evaluated using the modified Thomas Test Procedure depicted in Figure 2. The leg braces on both extremities were locked at 90" of knee flexion. One investigator flexed both hips up to the point at which the lumbar spine was flat against the table. The contralateral thigh was maintained in this flexed position while the ipsilateral thigh was lowered toward the table. Another investigator was positioned to prevent abduction or adduction of the thigh as it was slowly lowered into extension. The

subject was instructed to relax and let the leg stretch toward the floor. The third investigator, using the previously placed skin markings as guides, performed the goniometric measurements. The measurements were taken at the instant in which the thigh initially stopped moving into extension in response to the gravitational force. If the lower extremity was lacking 0' or more of hip extension ROM (I0 or greater of hip flexion), the stretching procedure was applied to the hip flexors of that thigh. Static Stretching Procedure

The subject positioning and stabilization procedures that were used for the hip extension ROM measurements were also utilized for static stretching of the hip flexors. Additionally, a velcro strap stabilized the contralateral thigh in hip flexion to assist in maintaining the pelvis in a position of posterior tilt. Also, a stretching force of 15% of the subject's body weight was applied using suspended weights through a strap around the subjects midthigh (Fig. 3). The stretching force was slowly applied, utilizing approximately 10-1 5 sec, to gradually lower the weights while loading the thigh. This stretching force was maintained for 2 minutes. Following this 2-minute period, the stretching force was gradually removed (10-15 sec). All of the subjects reported that this proce-

Figure 2. Hip extension ROM measurement.

JOSPT March 1989

STRETCHING EFFECTS ON HIP ROM AND GAIT ECONOMY


Figure 3. Static stretching procedures of hip flexors.

dure provided a strong stretching force but that they were able to relax their musculature during the stretch. The 2-minute stretch period was followed by a 2-minute period where the stretching force was removed and the leg was placed in a position of hip flexion. This cycle was repeated three times resulting in a total stretching time of 6 minutes interspaced by two, 2-minute periods of no stretch. Thus, the total intervention time for the static stretching procedure for one thigh was 10 minutes. If the subject demonstrated limited hip extension ROM in both lower extremities, one thigh received the 2-minute stretching force while the opposite thigh received a 2-minute period of no stretch. The subject positioning, stabilization, and weight loading procedures that were used for the hip flexion ROM measurements, were also used for static stretching of the hip extensors (Fig. 1). The intensity and duration of the stretch and nostretch periods were the same as outlined for the hip flexor static stretch. However, most of the subjects reported that the 15% of body weight load was greater than they could tolerate, as measured by their ability to relax their thigh musculature during the stretch, for the full 6 minutes of stretching. All were able to tolerate at least 10% of their body weight. The mean hip extensor stretching force was 11.0% of the subject's body weight. 354

STM/PNF Procedure

All of the STM/PNF procedures were performed by the same investigator (J. J. G.). The STM/PNF procedure for the hip flexors involved 1 minute of PNF using the lower extremity unilateral pattern of extension/abduction/internal rotation (12). This was followed by 8 minutes of STM applied to the hip flexors and then 1 minute of PNF repeating the extension/abduction/intemal rotation pattern. The STM/PNF procedure for the hip extensors involved 1 minute of PNF using the lower extremity unilateral pattern of flexionladduction/external rotation (12). This was followed by 8 minutes of STM applied to the hip extensors and then 1 minute of PNF repeating the flexion/ adduction/external rotation pattern. The selected PNF diagonal patterns were chosen because they facilitate contractions of muscles which are antagonistic to the myofascia associated with the limited hip motions. Active concentric muscle contractions were facilitated using maximum resistance applied to the tolerance of the weakest component of the diagonal. For example, if it was perceived by the investigator that abduction was the weakest component of the combined muscle contraction of the extension/abduction/internal rotation diagonal, the resistance was given with only enough force to match the strength of the abduction component while a smooth, coordi-

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nated diagonal pattern was performed. Also, during the facilitation of the lower extremity patterns, the investigator ensured that the lower trunk musculature provided balanced counter forces in order to maintain the proper trunk/pelvic girdle/ lower extremity alignment. The STM techniques chosen for this study consisted of manual pressure applied to the hypomobile, shortened myofascia. These techniques are similar to the connective tissue stretching associated with rolfing (9). The investigator who performed these techniques is a physical therapist as well as a certified rolfer. The STM applied to the hip flexors consisted of 4 minutes applied to the anterior thigh myofascia and 4 minutes applied to the hip flexors of the lower abdominal region, namely iliacus and psoas major. The STM applied to the hip extensors consisted of 4 minutes applied to the posterior thigh myofascia and 4 minutes applied to the hip extensors of the gluteal region. Statistical Procedures

The independent variables included the stretching procedure, static versus STMIPNF and testing prior to stretching (pre-test) versus testing following stretching (post-test). The dependent measures included oxygen consumption at each of the three treadmill speeds, ROM during hip flexion, and ROM during hip extension. Paired ttests were performed on each of these dependent variables to determine if there were significant changes caused by either of the two stretching procedures. All statistical analysis tests were made at the 0.05 level of significance. RESULTS

Prestretch Poststretch t Values Sianificance

Hip flexion 83O Hip extension -1 l o Values are means

+3 +3

107' -7'

+6

+3

5.30 6.13

p p

< 0.01

< 0.01

+ standard errors. TABLE 3

Range of motion of hip flexion and hip extension before and after a single bout of soft tissue mobilization and proprioceptive neuromuscular facilitation (STMIPNF) applied to the hip flexors and/or hip extensors of seven young adult males --

--

-

Prestretch Poststretch t Values Significance

+

Hip flexion 77O 3 Hip extension -13O f 3 Values are means

89O + 3 -4O + 1

3.6 3.2

p p

< 0.05 < 0.01


Oxygen consumption (ml/kg/min) at three workloads (40, 60, 80% of ofl lax) before and after a single bout of static stretching applied to the hip flexors andlor hip extensors of seven young adult males ~0,max

Prestretch

Values are means

Poststretch

t Values Significance


Oxygen consumption (mllkglmin) at three workloads (40, 60, 80% of ~ 0 m a xbefore ) and after a single bout of soft tissue mobilization and proprioceptive neuromuscular facilitation (STMIPNF) applied to the hip flexors andlor hip extensors of seven young adult males ~0,rnax

Hip ROM

Prestretch

Poststretch

t Values ~ i ~ n ' f i c a n c

%

Significant improvements in hip ROM were found for both the static and STM/PNF procedures (Tables 2 and 3). The static stretch procedure improved hip flexion by 24' (p