Immediate Effect of Tensor Fascia Latae. Stretching Exercise on Muscle Activity and. Hip Motion During Active Side lying Hip

Transcription

1 Immediate Effect of Tensor Fascia Latae Stretching Exercise on Muscle Activity and Hip Motion During Active Side lying Hip Abduction in Subjects With Tensor Fascia Latae Shortness Myungki Ji The Graduate School Yonsei University Department of Physical Therapy

2 Immediate Effect of Tensor Fascia Latae Stretching Exercise on Muscle Activity and Hip Motion During Active Side lying Hip Abduction in Subjects With Tensor Fascia Latae Shortness Myungki Ji The Graduate School Yonsei University Department of Physical Therapy

3 Immediate Effect of Tensor Fascia Latae Stretching Exercise on Muscle Activity and Hip Motion During Active Side lying Hip Abduction in Subjects With Tensor Fascia Latae Shortness A Masters Thesis Submitted to the Department of Physical Therapy and the Graduate School of Yonsei University in partial fulfillment of the requirements for the degree of Master of Science Myungki Ji June 2013

4 This certifies that the masters thesis of Myungki Ji is approved. Thesis Supervisor: Ohyun Kwon Chunghwi Yi: Thesis Committee Member #1 Heonseock Cynn: Thesis Committee Member #2 The Graduate School Yonsei University June 2013

5 Acknowledgements Many people contributed to my academic growth in preparing this thesis. First of all, I would like to express my profound appreciation to professor Oh yun Kwon for his help and support. He guided me in the research topic, and writing of my thesis. Furthermore, he gave me various advices and encouragement including enlightened me by saying Always think. Additionally, I want to express my deep gratitude to professor Chung hwi Yi for his great teaching who has various academic experiences and enormous knowledge. I would like to express my gratitude to professor Heon seock Cynn for his kindness and careful concern, giving me encouragement and intelligent advice. I also sincerely thank professors, Hye seon Jeon, Sung hyun You, and Sang hyun Cho, who helped expand my knowledge and perspective. I wish to thank sincerely my colleagues and friends, Kyue nam Park, Sung dae Choung, Il woo Park, and Min sue Cho, who have given me encouragement for better or worse. Thank all of your support. Also, I would like to thank all of the members in the Graduate School Department of Physical Therapy. They have provided me enormous mental support and assistance for my graduate course. I deeply appreciate all of the therapists and professors of the Seoul National University Bundang Hospital Department of Rehabilitation Medicine. They always gave me the time to study, opportunity, and valuable support. More than anybody, I wish to express my deep love and gratitude to all family who

6 always pray for me. My parents have provided endless love and mental support, and wife s parents have given me encouragement and careful concern. Especially my wife, Yoo jin and sons, Sung june, and Hye june have given me too much love and affection. Without their belief in me and encouragement, I could never have finished my graduate study. Finally, I thank and praise God. I was able to finish my thesis with grace and guidance by God. Thank you.

7 Table of Contents List of Figures iii List of Tables iv Abstract v Introduction 1 Method 5 1. Subjects 5 2. Experimental Equipment Surface Electromyography Electromagnetic Motion Tracking System Inclinometer 6 3. Clinical Measurement Tensor Fascia Latae Length Test With Inclinometer 7 4. Outcome Measurements Muscle Activity Kinematic Data Using Electromagnetic Motion Tracking System 9 5. Tensor Fascia Latae Stretching Exercise Active Tensor Fascia Latae Stretching Exercise Passive Tensor Fascia Latae Stretching Exercise Experimental Procedure 12 - i -

8 7. Statistical Analysis 14 Results General Characteristics of the Subjects Muscle Activity Hip Flexion and Internal Rotation Angle Tensor Fascia Latae Muscle Length 25 Discussion 27 Conclusion 32 References 33 Abstract in Korean 40 - ii -

9 List of Figures Figure 1. Active Tensor Fascia Latae Stretching Exercise 11 Figure 2. Passive Tensor Fascia Latae Stretching Exercise 11 Figure 3. Active Side Lying Hip Abduction 13 Figure 4. Gluteus Medius, Gluteus Maximus, and Tensor Fascia Latae Muscle Activity 20 Figure 5. Hip Flexion and Internal Rotation Angle 24 - iii -

10 List of Tables Table 1. General Characteristics of Subjects 16 Table 2. Comparison of Gluteus Medius, Gluteus Maximus, and Tensor Fascia Latae Muscle Activity Between Pre and Post Stretching Exercises 18 Table 3. Comparison of Effects on Gluteus Medius, Gluteus Maximus, and Tensor Fascia Latae Muscle Activity Between Passive and Active Tensor Fascia Latea Stretching Groups 19 Table 4. Comparison of Hip Flexion and Internal Rotation Angle Between Pre and Post Stretching Exercises 22 Table 5. Comparison of Effects on Hip Flexion and Internal Rotation Angle Between Passive and Active Tensor Fascia Latae Stretching Exercise Groups 23 Table 6. Comparison of Tensor Fascia Latae Muscle Length Between Pre and Post Stretching Exercises 26 Table 7. Comparison of Effect on Tensor Fascia Latae Muscle Length Between Passive and Active Tensor Fascia Latae Stretching Exercise Groups 26 - iv -

11 ABSTRACT Immediate Effect of Tensor Fascia Latae Stretching Exercise on Muscle Activity and Hip Motion During Active Side lying Hip Abduction in Subjects With Tensor Fascia Latae Shortness Myungki Ji Dept. of Physical Therapy The Graduate School Yonsei University The purposes of this study were to investigate the effect of tensor fascia latae (TFL) muscle stretching exercise on muscle activity and hip motion, and to compare the effects of the passive and active TFL stretching exercise during active side lying hip abduction in subjects who have TFL shortness. Twenty subjects with TFL shortness were recruited for this study and, using a random number table, were randomly assigned to two groups: the passive TFL stretching exercise group (PTS - v -

12 group) and the active TFL stretching exercise group (ATS group). The subjects were instructed how to perform PTS exercise or ATS exercise. Muscle activity of gluteus medius (Gmed), gluteus maximus (Gmax), and TFL was measured with surface electromyography (EMG), and electromagnetic motion tracking system was used to measure the hip flexion and internal rotation angle during active side lying hip abduction. Measurement of TFL length is elicited by modified Ober test with inclinometer. A paired t test was utilized for determining the differences between pre and post stretching exercise s outcome (muscle activity of Gmed, Gmax, and TFL, angle of hip flexion, and internal rotation, and TFL length). A comparison of the effect of outcome measure of both groups was completed by an independent t test. The level of significance was set at α = The results showed a significant increase in Gmed muscle activity and significant decrease in hip flexion angle between pre and post stretching exercise during active side lying hip abduction. Also, the results indicated that active TFL stretching exercise significantly increased the Gmax muscle activity than passive TFL stretching exercise. It decreased the TFL muscle activity, and decreased the hip flexion angle during active side lying hip abduction in subjects with TFL shortness. In conclusion, active TFL stretching exercise may be an effective method for modifying hip muscle activity and motion during active side lying hip abduction in people with TFL shortness. Key Words: Active stretching, Passive stretching, Side lying hip abduction, Tensor fascia latae shortness. - vi -

13 Introduction Hip abductor muscles play a major role in control of rotational alignment of the limb (Fulkerson 2002; Lee 1999; Neumann 2002). The middle portion of the gluteus medius (Gmed) muscle abducts the hip joint and the gluteus maximus (Gmax) muscle is an extensor and an external rotator of the hip joint (Cutter, and KerVorkian 1999; Neumann 2010). The superior portion of the Gmax also acts as a hip abductor during gait (Lyons et al. 1983). The Gmed provides frontal plane stability for the pelvis during walking and other functional activities (Earl 2004; Fredericson et al. 2000). The Gmed has a more vertical pull and help initiate hip abduction, which is then completed by the tensor fascia latae (TFL) (Gottschalk, Kourosh, and Leveau 1989). The TFL muscle acts through the iliotibial band (ITB) by pulling it superiorly and anteriorly (Gottschalk, Kourosh, and Leveau 1989). It assists in flexion, internal rotation, and abduction of the hip (Fredericson et al. 2000; Travell, and Simons 1998). Generally, one muscle dominates the movement pattern causing an imbalance to occur, which may lead to injury (Jull, and Janda 1987; Page, Clare, and Robert 2010; Sahrmann 2002). When muscle imbalance exists, some muscles are shortened and other muscles are weakened (Jull, and Janda 1987; Page, Clare, and Robert 2010). Muscle weakness is a common occurrence that arises in the synergistic muscles in the hip. The TFL becomes short and the posterior fiber of the Gmed becomes weak (Bewyer, and Bewyer 2003; Kendall et al. 2005). The imbalance of two synergistic muscles contributes to compensatory joint motion and the development of movement - 1 -

14 impairment (Sahrmann 2002). The weak Gmed is related to many injuries of the lower extremities and abnormalities in the gait cycle (Kendall et al. 2005). The TFL can become structurally short and mechanically incapable of lengthening to an appropriate level and the weak Gmed can become structurally long and incapable of shortening to an appropriate level (Comerford, and Mottram 2001; Kendall et al. 2005; Sahrmann 2002). When muscles are incapable of firing correctly, compensation occurs and this will alter joint motion and movement (Sahrmann 2002). Janda (1983) have hypothesized a common muscle imbalance pattern in shortness of the TFL in chronic musculoskeletal pain syndromes. Assessments of movement are considered an important part of the physical examination because movement may contribute to excessive stress and compression on joints, and muscle, resulting in musculoskeletal pain and various injuries (Sahrmann 2002). Janda (1983) suggested that in hip abduction movement pattern test, the sign of an altered movement pattern is the tensor mechanism of hip abduction facilitated by a short TFL. Instead of pure hip abduction in the plane of the trunk, the movement is combined with hip flexion due to the TFL s dual action as a hip flexor and abductor (Page, Clare, and Robert 2010). Sahrmann (2002) suggested that lack of posterolateral stabilization of the proximal femur is caused by impaired positioning and overstretch of the muscles of the hip. This impaired movement is associated with recruitment of TFL for hip abduction and flexion (Sahrmann 2002). Sahrmann (2002) proposed that in lower quarter examination, the TFL is dominant when hip flexes and - 2 -

15 the Gmed is weak when the hip is unable to tolerate during applying maximum resistance in side lying hip abduction with lateral rotation and extension. It has been suggested that there are relative to a shortened TFL and a weak Gmed with various lower extremity injuries and low back pain. Trendelenberg (1998) was the first to describe a hip drop upon weight bearing which indicated a Gmed weakness in the gait, and concluded that lateral leg stability was solely maintained by the tensile strength of the TFL. With a Trendelenburg gait, the pelvic drop occurs when the Gmed doesn t produce a sufficient internal hip abduction moment to balance the external hip adduction moment that occurs during single leg stance (Earl 2004). Therefore, those with a Trendelenberg gait will have reduced gait efficiency and be at greater risk of developing low back pain as a result of the pelvis not being stabilized during the gait and other activities or when performing unilateral weight training exercises (Bewyer, and Bewyer 2003; Earl 2004). Fredericson et al. (2000) suggested that ITB syndrome may occur as a result of weakness of the Gmed, which lead to decreased control of thigh abduction and external rotation. Fredericson et al. (2000) hypothesized that this sequence of events places the ITB under increased tension, making it more prone to impingement on the lateral epicondyle of the femur. Earl (2004) described patellofemoral pain syndrome as an overuse injury. Inhibition or dysfunction of the Gmed may contribute to decreased hip control, allowing greater femoral internal rotation (Hertel, Sloss, and Earl 2005). This produces a larger valgus vector at the knee, increasing the laterally directed forces acting on the patella (Earl 2004; Hertel, Sloss, and Earl 2005). Ober (1936) reviewed TFL shortness as a factor - 3 -

16 in low back pain. Duchenne (1949) attributed that lower extremity changes from the tough ITB contractures as femoral internal rotation, hip flexion contractures. In previous studies, intervention methods to lengthen TFL and increase gluteal muscle activity have been used. Fredericson et al. (2000) suggested that runners with ITB syndrome have weaker hip abduction strength in the affected leg compared with their unaffected leg. Through TFL ITB self stretching exercise, symptom improvement with a successful return to the pre injury training program parallels improvement in hip abductor strength (Fredericson, and Wolf 2005). Tyler et al. (2006) suggested that patients with patellofemoral pain syndrome have associated hip weakness. Also, improvements in TFL ITB flexibility were associated with excellent results in patients with patellofemoral pain syndrome (Tyler et al. 2006). Among previous studies related TFL stretching, hip muscle activity and hip motion were not demonstrated in side lying position. In addition, the comparison of passive and active TFL stretching exercise on hip muscle activity and motion was not established during active side lying hip abduction in subjects with TFL shortness. The purposes of this study were to investigate effect of TFL stretching exercise on hip muscle activity and hip motion, and to compare effects of passive and active TFL stretching exercise on muscle activity and hip motion during active side lying hip abduction in subjects with TFL shortness. The hypothesis of this study was that the stretching exercise on TFL increases the muscle activity of Gmed, and reduces angle of hip flexion and hip internal rotation during active side lying hip abduction in subjects with TFL shortness

17 Method 1. Subjects Twenty volunteers at the Yonsei University were recruited. The inclusion criteria for subject selection in this study included that the shortness of TFL were a positive sign by modified Ober test. Twenty subjects were randomly allocated into one of two exercise groups: passive TFL stretching exercise group, or active TFL stretching exercise group. Subjects with restricted passive range of motion of hip joint, history of direct trauma or surgery to the lower extremity, diagnosis with disease in hip joint, and significant weakness of Gmed, Gmax and TFL that interfere with hip abduction were excluded (Arab et al. 2010). Prior to the study, the principal investigator explained all procedures to the subjects, and all subjects signed an informed consent form. This study was approved by Yonsei University Wonju institutional review board

18 2. Experimental Equipment 2.1 Surface Electromyography Muscle activity was measured using a Noraxon Telemyo 2400T (Noraxon, INC., Scottsdale, AZ, USA) with a pair of Ag AgCl surface electrodes 2cm in diameter. Raw electromyography (EMG) signals were band pass sampled at 1000Hz, filtered between 20 and 450Hz, and converted to root mean square using the MyoResearch Master Edition 1.06 XP software (Noraxon, INC., Scottsdale, AZ, USA). 2.2 Electromagnetic Motion Tracking System An electromagnetic motion tracking system (Liberty Polhemus, Colchester, VT, USA) was used to measure angle of hip flexion and internal rotation. This system consists of a transmitter, receivers, digitizers and a system electronics unit. 2.3 Inclinometer An inclinometer (Johnson Magnetic Angle Locator, Johnson, Mequon, WI, USA) is a circular shape with a weighted needle that indicates the number of degrees on a scale of a protractor. An inclinometer with markings at 1 increments was used for the measurement of TFL length

19 3. Clinical Measurement 3.1 Tensor Fascia Latae Length Test With Inclinometer Measure of TFL length is elicited by modified Ober test with inclinometer. The subjects were asked to lie laterally recumbent with the affected side uppermost. The affected lower limb was then brought into full extension by the examiner, with some abduction at the hip and the knee is extended. The examiner then slowly releases support of the limb, allowing the limb to fall into adduction past the neutral position. A short TFL restricts adduction and prevents the knee from falling past the neutral position. An inclinometer was used during the modified Ober test to measure hip adduction as an indication of TFL flexibility. Bandy et al. (2003) purposed that the use of an inclinometer to measure hip adduction using the modified Ober test appears to be a reliable method for the measurement of TFL length. During each measurement session, subjects were positioned lying down with their tested side facing up. The inclinometer was positioned at the popliteal fossa of the knee on the involved side using the double sided tape to hold it securely in place, and hip adduction was measured using the modified Ober test. If the limb was horizontal, it was considered to be at 0 degrees, below horizontal (adducted) was recorded as a positive number, and above horizontal (abducted) was recorded as a negative number (Bandy et al. 2003)

20 4. Outcome Measurements 4.1 Muscle Activity Prior to electrode placement, the electrode sites were shaved and cleaned with rubbing alcohol to prepare the skin. The electrode placement for the Gmax was middle area in the line between greater trochanter and second sacrum spinous process (S2). The electrode placement for Gmed was proximally 2cm area in the line between iliac crest and greater trochanter of femur. The electrode on TFL was attached on the 2cm area below anterior superior iliac spine (ASIS). Raw data was processed into the root mean square (RMS) with a moving window of 50 milliseconds. For normalization, the mean RMS of three trials of 5 seconds maximal voluntary isometric contraction (MVIC) was calculated for Gmed, Gmax and TFL. The MVIC for the Gmax was tested such that hip extension was resisted with the subject lying fully prone, with the knee flexed to 90. The MVIC for the Gmed was obtained during resisted hip abduction while subjects were lying in supine position on the treatment table. Subjects exerted maximal abduction force against resistance on the distal lateral leg, in a position of 30 of hip abduction, with the hip and knee at 0 of flexion. The MVIC for the TFL was acquired in the same supine position used for the Gmed, except that the hip was positioned in 45 between the sagittal and coronal planes (Kendall et al. 2005)

21 4.2 Kinematic Data Using Electromagnetic Motion Tracking System The receivers were mounted to thermoplastic frames and secured firmly to lower third of the lateral thigh and over the first sacrum spinous process (S1) with double sided tape. An anatomically relevant reference system for identifying the hip joint centre was defined with a predicative method based on each subject s pelvic and lower limb anthropometrics (Bush, and Gutowski 2003). Using anatomically relevant local coordinate axes derived from digitized bony landmarks data were reduced using standard matrix transformations to determine the rotational matrix of the femur with respect to the pelvis. Coronal plane motion was calculated as a composite angle between hip and pelvis rotating about the sagittal axis of the pelvis. Transverse plane motion was calculated as relative angle about the vertical axis (Bussey, Milosavljevic, and Bell 2009). Thus, hip motion is described in three angles of movement in the side lying position; abduction (in the sagittal plane), flexion (in the transverse plane) and rotation (in the coronal plane)

22 5. Tensor Fascia Latae Stretching Exercise 5.1 Active Tensor Fasica Latae Stretching Exercise Active stretching exercise begins with the subject lying in prone position on the treatment table. The subjects were asked to hip being positioned in rotation 0 and adduction 0, and flexed the knee 90. The opposite hip was in the neutral rotation and full knee extension. The subject slowly rotated the hip externally before separating the ASIS of the pelvis in a direction to the upper side from the floor of the table with pelvis hold to hand. This motion continues until the subject feels a stretch on the side of the hip around the greater trochanter. The subjects were instructed to maintain this position for 30 seconds and then rest for 30 seconds. The subjects were asked to perform this exercise for 10 sets (Figure 1). 5.2 Passive Tensor Fascia Latae Stretching Exercise Passive stretching exercise started in the same position as active stretching exercise. The examiner conducted subjects to stretching exercise. The examiner executed the exercise with his hand, holding pelvis with one hand and holding ankle with the other hand. The examiner applied subjects to rotate the hip externally until the examiner feels the end feel. The examiner maintained this position for 30 seconds and the rest for 30 seconds. This exercise completed 10 sets (Figure 2)

23 Figure 1. Active Tensor Fascia Latae Stretching Exercise. Figure 2. Passive Tensor Fascia Latae Stretching Exercise

24 6. Experimental Procedure All subjects were evaluated for study inclusion/exclusion at the visit. The length of each subject s TFL was assessed by modified Ober test with inclinometer. The angle of the hip motion and EMG data were collected during active hip abduction in side lying position. The subjects were asked to lie on the table in side lying position and the leg on the table was flexed to 45 at the hip and 90 at the knee. The subjects were instructed to perform three times of active hip abduction extending knee (Figure 3). A target bar was placed to control the angle of the abducted hip. The target bar was placed at 20 hip abduction position. The subject was asked to abduct their hip until their ankle touched target bar and hold the position for 5 seconds. When the subjects performed this motion, the examiner was not involved in any of the verbal cue and touch. A large board was used to minimize the movement of pelvic, back, and neck related to hip motion. The angle for hip was collected three times for the tested side. The angle of the hip motion was measured using an electromagnetic motion tracking system. EMG data were collected in three times by surface EMG and were normalized by percent of MVIC. Subjects were allowed to rest for 1 minute between trials. Following the pre stretching exercise measurement, the subjects received instruction in each TFL stretching exercise by a licensed physical therapist with 7 years of clinical experience. All measurements were performed three times at

25 the time of entry into the study and at the direct time after each TFL stretching exercise (pre and post stretching exercise). Figure 3. Active Side Lying Hip Abduction

26 7. Statistical Analysis The data are expressed as the means ± standard deviations. Statistical significance between pre and post stretching exercise measurement was assessed through paired t test. This method was used to assess statistical significance of muscle activity of Gmed, Gmax, and TFL, angle of hip flexion and internal rotation, and TFL length. The independent t tests were used to evaluate statistical significance of effects on muscle activity for Gmed, Gmax, and TFL, angle of hip flexion and internal rotation, and TFL length between passive and active stretching groups. The level of statistical significance was set at p < All statistical analysis was performed using the statistical package for the Social Sciences for windows version 18.0 (SPSS, Inc., Chicago, IL, USA)

27 Results 1. General Characteristics of the Subjects The general characteristics of the subjects including age, height, weight, body mass index (BMI) are shown in Table 1. There were no significant differences in parameters between passive TFL stretching exercise group and active TFL stretching exercise group (p > 0.05)

28 Table 1. General characteristics of the subjects. (N=20) Parameters Passive TFL a stretching group (n 1 =10) Active TFL stretching group (n 2 =10) Age (yrs) 23.4 ± 2.5 b 23.3 ± Height (cm) ± ± Weight (kg) 67.8 ± ± BMI c (kg/m 2 ) 22.4 ± ± a TFL: Tensor fascia latae. b Mean ± standard deviation. c BMI: Body mass index. p value is comparison of groups using an independent t test. t p

29 2. Muscle Activity The muscle activity of the post exercise Gmed was significantly greater than the pre exercise Gmed muscle activity (p<0.05). The post exercise Gmax muscle activity showed significantly greater activity when it was compared with the pre exercise Gmax in active TFL stretching exercise group (p<0.05). The post exercise TFL muscle activity was significantly lower than the pre exercise in active TFL stretching exercise group (p<0.05). However, there was no significant difference in Gmax muscle activity between the pre and post stretching exercise in passive TFL stretching group (p>0.05). Also, there was no significant difference in TFL muscle activity between the pre and post stretching exercise in passive TFL stretching group (p>0.05) (Table 2) (Figure 4). There was significant difference in effects on Gmax or TFL muscle activity between passive and active TFL stretching groups (p<0.05). However, there was no significant difference in effect on Gmed muscle activity between passive and active TFL stretching groups (p>0.05) (Table 3) (Figure 4)

30 Table 2. Comparison of gluteus medius, gluteus maximus, and tensor fascia latae muscle activity between pre and post stretching exercises. Muscle Group Pre Stretching exercise Post t p Gmed a PTS d ± f ± <0.01 * ATS e ± ± * Gmax b PTS ± ± ATS ± ± * TFL c PTS ± ± ATS ± ± * a Gmed: Gluteus medius. b Gmax: Gluteus maximus. c TFL: Tensor fascia latae. d PTS: Passive tensor fascia latae stretching exercise. e ATS: Active tensor fascia latae stretching exercise. f Mean ± standard deviation. * p < 0.05, p value is comparison of pre and post stretching exercise using paired t test

31 Table 3. Comparison of effects on gluteus medius, gluteus maximus, and tensor fascia latae muscle activity between passive and active tensor fascia latae stretching groups. Muscle PTS d Group ATS e t p Gmed a 7.17 ± 3.64 f 8.46 ± Gmax b ± ± * TFL c 1.07 ± ± * a Gmed: Gluteus medius. b Gmax: Gluteus maximus. c TFL: Tensor fascia latae. d PTS: Passive tensor fascia latae stretching exercise. e ATS: Active tensor fascia latae stretching exercise. f Mean ± standard deviation. * p < 0.05, p value is comparison of passive and active stretching exercise using independent t-test

32 Figure 4. Gluteus medius, gluteus maximus, and tensor fascia latae muscle activity. prepts: Pre passive tensor fascia latae stretching exercise. postpts: Post passive tensor fascia latae stretching exercise. preats: Pre active tensor fascia latae stretching exercise. postats: Post active tensor fascia latae stretching exercise. Gmed: Gluteus medius. Gmax: Gluteus maximus. TFL: Tensor fascia latae. *p<0.05: significant difference between pre post test. **p<0.05: significant mean difference between passive tensor fascia latae stretching and active tensor fascia latae stretching exercise groups

33 3. Hip Flexion and Internal Rotation Angle The angle of post exercise hip flexion was significantly lower than pre exercise hip flexion (p<0.05). The post exercise internal rotation was significantly lower than pre exercise internal rotation in active stretching group (p<0.05). However, there was no significant difference in internal rotation angle between pre and post stretching exercise in passive stretching group (p>0.05) (Table 4) (Figure 5). There was significant difference in effect on flexion angle between passive and active stretching groups (p<0.05). However, there was no significant difference in effect on internal rotation angle between passive and active stretching groups (p>0.05) (Table 5) (Figure 5)

34 Table 4. Comparison of hip flexion and internal rotation angle between pre and post stretching exercises. Hip motion Group Pre Stretching exercise Post t p Flexion PTS b ± 4.70 d 8.31 ± * ATS c ± ± <0.01 * IR a PTS ± ± ATS ± ± * a IR: Internal rotation. b PTS: Passive tensor fascia latae stretching exercise. c ATS: Active tensor fascia latae stretching exercise. d Mean ± standard deviation * p < 0.05, p value is comparison of pre and post stretching exercise using paired t test

35 Table 5. Comparison of effects on hip flexion and internal rotation angle between passive and active tensor fascia latae stretching exercise groups. Hip motion PTS b Group ATS c t p Flexion ± 2.31 d ± <0.01 * IR a ± ± a IR: Internal rotation. b PTS: Passive tensor fascia latae stretching exercise. c ATS: Active tensor fascia latae stretching exercise. d Mean ± standard deviation. * p < 0.05, p value is comparison of passive and active TFL stretching exercise using independent t test

36 Figure 5. Hip flexion and internal rotation angle. prepts: Pre passive tensor fascia latae stretching exercise. postpts: Post passive tensor fascia latae stretching exercise. preats: Pre active tensor fascia latae stretching exercise. postats: Post active tensor fascia latae stretching exercise. IR: internal rotation. *p<0.05: significant difference between pre post test. **p<0.05: significant mean difference between passive tensor fascia latae stretching and active tensor fascia latae stretching exercise groups

37 4. Tensor Fascia Latae Muscle Length The TFL length of post exercise was significantly greater than pre exercise (p<0.05) (Table 6). However, there was no significant difference in effect on TFL length between passive and active TFL stretching groups (p>0.05) (Table 7)

38 Table 6. Comparison of tensor fascia latae muscle length between pre and post stretching exercises. Group Pre Stretching exercise Post t p TFL a length ( ) PTS b ± 2.39 d ± <0.01 * ATS c ± ± <0.01 * a TFL: Tensor fascia latae. b PTS: Passive tensor fascia latae stretching exercise. c ATS: Active tensor fascia latae stretching exercise. d Mean ± standard deviation. * p < 0.05, p value is comparison of pre and post stretching exercise using paired t test. Table 7. Comparison of effect on tensor fascia latae muscle length between passive and active tensor fascia latae stretching exercise groups. Group t p PTS b ATS c TFL a length ( ) 4.70 ± 2.75 d 7.10 ± a TFL: Tensor fascia latae. b PTS: Passive tensor fascia latae stretching exercise. c ATS: Active tensor fascia latae stretching exercise. d Mean ± standard deviation. * p < 0.05, p value is comparison of passive and active TFL stretching exercise using independent t test

39 Discussion The purposes of the present study were to investigate the effect of TFL stretching exercise on hip muscle activity and hip motion in subject with TFL shortness, and compare effects on muscle activity and hip motion between passive and active TFL stretching exercises during active side lying hip abduction. The result showed that the muscle activity of the post exercise Gmed was significantly greater than the pre exercise. Also, the muscle activity of the post exercise TFL was significantly lower than the pre exercise in active stretching group. There are several possible explanations for lower muscle activity of TFL during active side lying hip abduction. First of all, mechanical factors involving the viscoelastic properties of the muscle may affect the muscle s length-tension relationship. Previous studies (Kokkonen, Nelson, and Cornwell 1998; Nelson, and Kokkonen 2001) have suggested that the primary mechanism underlying the stretching induced decreases in force may alter the muscle length tension relationship. Secondly, it has also been hypothesized that neural factors contribute to the stretching induced decrease in force. A number of peripheral mechanisms have been proposed to explain the reduced muscle activation after stretching (Avela et al. 1999; Behm, Button, and Butt 2001; Fowles, Sale, and MacDougall 2000). The peripheral mechanism includes the autogenic inhibition of the Golgi tendon reflex, mechanoreceptor and nociceptor afferent inhibition, joint pressure feedback inhibition

40 due to excessive ranges of motion during stretching, and stretching reflex inhibition originating from the muscle spindle. Additionally, Avela et al. (1999) suggested that a central nervous system mechanism may be responsible for the decreases in muscle activation. The increase in Gmed activation and decrease in TFL following the stretching exercise was contrary with the original hypothesis that their activation would respectively reduce and increase in subject with TFL shortness (Fredericson, and Weir 2006). Some investigators have also hypothesized a common muscle imbalance pattern of weakness in hip abductor and shortness of TFL (Sahrmann 2002; Comerford, and Mottram 2001). It is assumed that when the primary muscle responsible for hip abduction; gluteus medius, is weakened, the synergistic muscle; TFL, is substituted and becomes overactive to be the primary muscle (Sahrmann 2002; Comerford, and Mottram 2001). Hence, in theory, it is thought that hip abductor increase is accompanied with TFL decrease in these subjects. Finally, this study suggests that the TFL stretching exercise affect increase of Gmed activation and decrease of TFL muscle activity during active side lying hip abduction in subjects with TFL shortness. The results of this study indicate that hip flexion is significantly decreased during active side lying hip abduction following stretching exercises. Also, the angle of the post exercise internal rotation was significantly lower than the pre exercise in active stretching exercise group. There are numerous possible reasons for these results. Firstly, although the Gmed and TFL are both hip abductors, the Gmed,

41 especially the posterior fiber of Gmed is an external rotator of the hip and TFL is an internal rotator and a flexor of hip. Thus, the function of hip abductor muscle following the stretching exercise could not be completely substituted by TFL, but the function of hip abductor muscle could be acted by Gmed. In the second place, it is assumed that when primary muscle responsible for a specific joint movement is weakened, the synergistic muscle is substituted and becomes overactive to be the primary muscle responsible for the movement (Sahrmann 2002). Based on this hypothesis, it is speculated that TFL shortness is a compensatory mechanism. Accordingly, TFL stretching exercise allows the subjects with TFL shortness to be responsible for the activation of the primary muscle: Gmed, during the hip abduction. Therefore, this study recommended that TFL stretching exercise affects decrease of hip flexion and internal rotation angle during active side lying hip abduction in subjects with TFL shortness. Hip flexion angle between pre and post stretching exercise differences were ± 2.31 in passive TFL stretching exercise group and ± 3.45 in active TFL stretching exercise group. Our results indicate that the active TFL stretching exercise decreased the hip flexion angle significantly more than the passive TFL stretching exercise during active side lying hip abduction. Also, the differences of Gmax and TFL muscle activity between pre and post stretching exercise were ± and 1.07 ± 3.54 in passive TFL stretching exercise group, and ± and ± in active TFL stretching exercise group, respectively. The results indicate that the active TFL stretching exercise increased the muscle activity of

42 Gmax and decreased TFL muscle activity significantly more than the passive TFL stretching exercise during active side lying hip abduction. Nonetheless, there was no significant difference in effects of TFL stretching exercise on hip internal rotation angle, the muscle activity of Gmed, and TFL length between passive and active stretching exercise groups. Previous studies (Medeiros et al. 1977; Tanigawa 1972; Taylor et al. 1990) proposed that improvements made by patients using passive stretching may be the result of both autogenic inhibition and tensile stress applied to the muscle according to muscles viscoelastic characteristics; when stress is applied over a constant period of time, the muscle will gradually relax and increase in length. With autogenic inhibition, the muscle being stretched is inhibited and is thought to simultaneously relax. Active stretching also places a tensile stress on the muscle being stretched, but additional increases in length are thought to be achieved through relaxation via reciprocal inhibition (Kandel, Schwartz, and Jessell 2000). Although the neurologic mechanisms of muscle relaxation in active and passive stretching are thought to be different, tensile stress is common to both types of stretching and is probably the primary factor for increasing muscle flexibility. This could explain various results about this topic. White, and Sahrmann (1994) suggested that active stretching increase the flexibility of the tight muscles while concomitantly improving function of the antagonistic muscles. This study assessed the effect of stretching type on the function of the antagonist muscles. There are significant differences in effects on Gmax muscle activity between passive and active stretching exercises. Consequently, present study suggests that active stretching exercise was more

43 effective than passive stretching exercise on Gmax and TFL muscle activity, and hip flexion angle during active side lying hip abduction in people with TFL shortness. Both post exercise showed a significantly greater increase in the length of TFL than pre exercise. The present study showed that TFL stretching exercise lengthened the TFL muscle. Our results are consistent with those of a previous study showing that stretching TFL is an effective method for increasing TFL length (Fredericson et al. 2002). Therefore, this study suggests that TFL stretching exercise in this study was effective method for elongating the TFL. The present study has several limitations. First of all, we did not directly measure the length of TFL muscle. Besides, we studied the effect of the TFL stretching exercise, and it is not clear whether our results can be generalized to other functional activities in subjects with TFL shortness. In addition, generalization of the study is limited because a small number of subjects participated and our subjects were young. Finally, the stretching exercise was a short term intervention. Further studies are needed to determine the long term effect of TFL stretching on hip motion and muscle activity during active side lying hip abduction in more subjects than present subjects with TFL shortness

44 Conclusion The present study investigated the effect of the TFL stretching exercise on hip muscle activity and motion, and compared the effect of the passive and active stretching exercise during active side lying hip abduction in subjects with TFL shortness. The findings of this study showed significant increase in Gmed muscle activity and significant decrease in hip flexion angle between pre and post stretching exercise during active side lying hip abduction. The results indicate that active stretching exercise is compared with passive stretching exercise significantly increased the Gmax muscle activity, decreased the TFL muscle activity, and decreased the hip flexion angle during active side lying hip abduction in subjects with TFL shortness. In conclusion, active TFL stretching exercise may be an effective method for modifying hip muscle activity and motion during active side lying hip abduction in people with TFL shortness. In its final analysis, the findings of the present study provide evidence for the effectiveness of TFL stretching in subjects with TFL shortness

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52 국문요약 넙다리근막긴장근단축대상자에게신장운동이 근활성도와엉덩관절움직임에미치는즉각적인영향 연세대학교대학원 물리치료학과 지명기 본연구의목적은넙다리근막긴장근이단축된대상자에게수동적넙다리근막긴장근신장운동과능동적넙다리근막긴장근신장운동을시킨후옆으로누운자세에서엉덩관절벌림시근활성도와엉덩관절움직임에미치는영향을알아보고수동적신장운동과능동적신장운동의효과를비교하는것이다. 본연구를위해넙다리근막긴장근이단축된 20명의대상자가참여하였고, 수동적넙다리근막긴장근신장운동집단과능동적넙다리근막긴장근신장운동집단에난수표를이용하여무작위로할당하였다. 각각의대상자들은수동적신장운동이나능동적신장운동수행방법을교육받았다

53 중간볼기근, 큰볼기근, 그리고넙다리근막긴장근의근활성도는표면근전도장비를사용하여측정하였고전자기움직임추적시스템은옆으로누워엉덩관절벌림시엉덩관절의굽힘과안쪽돌림각도를측정하는데사용하였다. 중간볼기근, 큰볼기근과넙다리근막긴장근의근활성도, 엉덩관절굽힘과안쪽돌림의각도, 그리고넙다리근막긴장근의길이에대한신장운동전과후간차이를알아보기위해짝비교 t 검정을하였다. 수동적신장운동집단과능동적신장운동집단간의차이가있는지를알아보기위해독립 t 검정을하였다. 통계학적유의수준 α = 0.05로하였다. 연구결과옆으로누워엉덩관절벌림시신장운동전과후중간볼기근의근활성도는유의하게증가하였으며, 엉덩관절굽힘각도는유의하게줄어들었다. 또한, 수동적넙다리근막긴장근신장운동과비교하여능동적넙다리근막긴장근신장운동이넙다리근막긴장근이단축된대상자가옆으로누워엉덩관절을벌림시유의하게큰볼기근의근활성도는증가하였고넙다리근막긴장근의근활성도는감소하였으며, 엉덩관절굽힘각도는유의하게감소하였다. 결론적으로, 능동적넙다리근막긴장근신장운동이넙다리근막긴장근이단축된사람들이옆으로누워엉덩관절을벌림시엉덩관절근활성도와움직임을교정하는데효과적인중재방법으로사료된다. 핵심되는말 : 넙다리근막긴장근단축, 능동적신장, 수동적신장, 옆으로누워엉덩관절벌림