Earticle

This study aimed to compare the short-term effects of sciatic nerve neural sliding and neural stretching exercises on hamstring muscle length and functional flexibility in wrestlers. The study participants in-cluded 74 wrestlers. The athletes were randomly divided into two groups: neural sliding and neural stretching groups. The hamstring flexibility and the functional flexibility were assessed using the active knee ex-tension limitation (AKEL) angle and the sit and reach (SR) test one day before and immediately after the neural mobilization exercises, respec-tively. A three-way repeated measures analysis of variance was con-ducted that examined the effect of mobilization type, time, and gender on interest in AKEL right leg, AKEL left leg, and SR test. There is not a significant difference between the effect of two different mobilizations on AKEL right and left leg, and SR test (P>0.05). It was determined there is statistically significant differences between premobilization and post-mobilization outcome measures for AKEL right leg (F=59.886, P=0.001), AKEL left leg (F=31.896, P=0.001), and SR test (F=22.630, P=0.001). There is not a statistically significant difference between males and females by these three measures neural sliding and neural stretching exercises to the sciatic nerve in wrestlers were effective in increasing hamstring flexibility and functional flexibility and not superior to each other.

This study aimed to determine whether foam roller with vibration (FRV) can improve hamstring flexibility and jump performance in young adults. Twenty subjects were randomly allocated into either the FRV or the foam- roller with no vibration (FRNV) groups. The vibration of the vibration foam-roller was 32 Hz. All participants completed one 10-min session on the hamstring. Active straight leg raising (ASLR) test in supine posi-tion and active knee extension (AKE) test in sitting position were per-formed to measure hamstring flexibility, before and immediately after the session. ASLR, AKE, and vertical jump performance test were per-formed before the session and immediately after the session. Analysis of covariance was used to determine statistical significance. ASLR and AKE tests were significantly different between FRV and FRNV, except the right hamstring. There was significant improvement with respect to ASLR and AKE tests after the session in FRV group. The vertical jump perfor-mance test of both groups was not significantly different after the ses-sion. FRV is more effective than FRNV for improving hamstring flexibility.

The purpose of this study was to investigate the effects of extracorporeal shock wave therapy on asymmetric hamstring and back pain in patients with non-specific chronic back pain. Twenty-nine subjects with nonspecific chronic low back pain were classified into experimental group (n=15) and control group (n=14). Outcome measures included hamstring length, hamstring length difference, compensative lumbar flexion and rotation, hamstring thickness, disability index, and pain intensity. The experimental group performed extracorporeal shock wave and stretching technique twice a week for three weeks, and the control group performed the stretching technique twice a week for three weeks. Extracorporeal shock waves applied 4 pressure (0.37 mJ/mm), and 2,000 shocks to the hamstring with 10 Hz. Stretching techniques are applied after extracorporeal shock wave therapy. There was a significant difference of dependent variables in the experimental group, and in the control group, there was a significant difference except for lumbar rotation. In between-group comparison, the experimental group showed signifiacnlty greater lumbar flexion and thickness of biceps femoris compared to the control group. Based on these results, we recommend extracorporeal shock wave therapy as an intervention that can reduce compensatory lumbar rotation and lengthen shortened hamstrings.

This study aimed to identify alterations in the thickness of the hamstring and the muscle tone in response to soft tissue mobilization (STM), passive stretching (PS), and muscle energy technique (MET). Forty-five male subjects with no orthopedic or neurological diseases volunteered to participate in the study, which were allocated either the SEM, PS, or MET groups, 10 in each. Outcome measure included the thickness and muscle tone of the hamstring. Intervention was an isometric contraction and 10-sec stretching for the STM group, a 10 repetitions of 10-sec stretch for the PS group, and an isometric contraction and relaxation for the MET group. Pre- and post-treatment changes in the thickness and muscle tone of hamstring were significantly different for the three groups (p<.05). However, there were not found statistically significant differences in the thickness and muscle tone of hamstring between the groups (p>.05). This study suggests that all tree methods may be helpful to increase the condition of hamstring. Further studies with robust design will be needed for the generality of our results.

본 연구는 수동적 불충분 스트레칭 적용에 따른 관절의 가동 범위와 햄스트링 근육의 근활성도를 분석하는데 연구 의 목적이 있다. 이를 위하여, 대학에 재학하고 있는 체육 계열 학생들로 편의표본추출 방법(Convenience Sampling Method)에 의해 표본을 추출하였고, 고관절 굴곡 운동 시 햄스트링 근육을 스트레칭 하는데 정형외과적 질환이 없는 학생 18명을 연구 대상으로 선정하였다. 스트레칭 유형별 사전 사후의 관절 가동 범위와 햄스트링 근육의 근활성도를 측정하였고 측정결과는 반복측정분산 분석을 사용하였다. 연구 결과는 다음과 같다. 첫째, 보편적 스트레칭과 수동적 불충분 스트레칭 유형에 따른 관절의 가동 범위는 통계적으로 유의한 차이가 나타났다. 관절의 가동 범위는 집단 간의 차이는 유의하지 않았지만, 집단과 측정 시점 간의 상호작용에 대한 주 효과가 유의하게 나타나 수동적 불충분 스트레칭이 보편적 스트레칭에 비해 관절의 가동 범위를 증가 시켜주는 것으로 나타났다. 둘째, 보편적 스트레칭과 수동적 불충분 스트레칭 유형에 따른 반건양근의 근활성도와 대퇴이두근의 근활성도는 통계적으로 유의한 차이가 나타나지 않았다.

The purpose of this study is to analyze the range of motion of joints and muscle activity of hamstring muscles according to the application of passive insufficient stretching. For this purpose, a sample was extracted from college students majoring in physical education using the convenience sampling method, and eighteen students without orthopedic conditions were selected as the subjects for a study on stretching the hamstring muscles during hip flexion. The range of motion of the joint and the muscle activity of hamstring before and after stretching for each type of stretching were measured, and the measurement results were analyzed using repeated measures analysis of variance. The research results are as follows: First, there was a statistically significant difference in the range of motion of the hip joint according to the type of universal stretching and passive insufficient stretching. Although there was no significant difference between groups in the range of motion of the joint, a significant main effect for the interaction between group and measurement time was observed, indicating that passive insufficient stretching increased the range of motion of the joint compared to universal stretching. Second, there was no statistically significant difference in the muscle activation of the semitendinosus and the biceps femoris according to the type of universal stretching and passive insufficient stretching.

Purpose: We investigated the effects of the hold-relax and foam roller techniques on the range of motion, flexibility, and tone of shortened hamstring muscles. Method: The study included 24 participants who were randomly categorized into hold-relax and foam roller groups. Both groups performed the assigned task thrice a week for a total of 5 sets of 15 s each on the hamstring muscles for 6 weeks. Range of motion was evaluated using a goniometer, flexibility was evaluated using the sit and reach test, and muscle tone was measured using a myotone. We evaluated joint range of motion, flexibility, and muscle tone pre- and 6 weeks post intervention in both groups. Results: We observed a significant intergroup difference in range of motion and flexibility after 6-week training. Conclusion: The hold-relax technique was more effective than the foam roller technique for stretching exercise to improve range of motion and flexibility of shortened hamstring muscles.

PURPOSE: The current generation has shortened hamstrings due to a sedentary lifestyle, resulting in reduced flexibility of the hamstring and dysfunction. This study was undertaken to compare effects of three different release exercises on hamstring flexibility, in participants with short hamstrings. METHODS: Totally, 20 subjects having short hamstrings were involved in this study. The inclusion criterion for study participation was active knee extension test (AKET) less than 60°. All participants were subjected to 3 methods: hamstring foam roller release (HFRR), sitting self myofascial release (sitting SMR), and standing self myofascial release (Standing SMR). All participants randomly performed all three methods to avoid bias caused by learning or fatigue. Passive knee extension test (PKET), AKET, finger to floor distance test (FTFT), and pelvic tilting angle test (PTAT) were measured pre- and post-exercises. RESULTS: The PKET, AKET and FTFT were significantly increased after HFRR, sitting SMR, and standing SMR exercise (p < .05). However, PTAT was not significantly increased after the three exercises (p > .05). Furthermore, no significant differences were observed between PKET, AKET, FTFT and PTAT subsequent to HFRR, sitting SMR, and standing SMR (p > .05). CONCLUSION: Our results indicate that HFRR, sitting SMR and standing SMR were immediately effective in improving hamstring flexibility in participants with short hamstrings.

Background Jack-knife stretching is a newly developed static hamstring stretching exercise. However, no studies have compared this stretching exercise to hamstring stretching with proprioceptive neuromuscular facilitation (PNF). Purpose This study compared the effects of PNF hamstring stretching and jack-knife stretching on hamstring flexibility. Study design Randomized controlled clinical trial Methods Twenty-four adults with bilateral hamstring tightness were randomly assigned to the PNF hamstring stretching or jack-knife stretching group. All participants performed PNF hamstring stretching or jack-knife stretching for 150 s. Before and after hamstring stretching, the participants completed the active knee extension (AKE), active straight leg raise (ASLR), and finger-to-floor distance (FFD) tests. Lumbar flexion and the anterior pelvic tilt angle were measured during the FFD test. Results Both hamstring stretching exercises increased the knee extension angle during the AKE test, hip flexion angle during the ASLR test, and lumbar flexion and anterior pelvic tilt angle during the FFD test while decreasing the FFD value (p<0.05). However, no significant between-group differences were found (p>0.05). Conclusions PNF hamstring stretching and jack-knife stretching have similar beneficial effects on hamstring flexibility.

Background: Hamstring shortness (HS) contributes to the limit of hip and knee range of motion and can limit the execution of multi-segmental movement exercises such as squatting, thereby altering the muscle activation. The double leg squat (DS) is fundamental exercise for knee injury rehabilitation programs. However, it may aggravate knee joint injury and cause low back pain. The Bulgarian split squat (BSS) is a one-leg squat exercise with greater knee joint stability than DS. Measuring muscle activation during the squat will provide insight into the contribution of hamstring activation and quadriceps and hamstring (Q:H) ratio to the knee in participants with HS. Objects: This study compares hamstring activation and Q:H ratios during squat exercises in individuals with and without HS. Methods: This study classified 30 healthy participants, based on active knee extension, into two groups: with HS and without HS. Surface electromyography was performed to determine muscle activation of the medial hamstring (MH) and biceps femoris of the hamstrings and coactivation of the Q:H. All participants performed DS and BSS. Results: MH activity was significantly higher in the with HS group than in the without HS group during all exercises, and the Q:H ratio was significantly closer to 1.0 during BBS compared to DS. Additionally, the with HS group had a significantly lower Q:H ratio than without HS group. Conclusion: In comparison between exercises, BBS can bring the Q:H ratio closer to 1.0 compared to DS, which may enhance knee stability. However, in between-group comparisons, the increased tension due to the shortening of the hamstrings leads to heightened hamstring activation, resulting in a Q:H ratio that is closer to 1.0 compared to the without HS group. Therefore, relying solely on the Q:H ratio to assess knee stability may be risky.

Objective: This study was conducted to compare the immediate effect of hamstring stretching techniques of static stretching, proprioceptive neuromuscular facilitation (PNF) hold-relax and PNF irradiation on the hamstring muscle. Design: Three-group pretest-posttest design. Methods: Fifty-one subjects with shortened hamstrings were randomly assigned to the static stretching group (n=17), PNF hold-relax group (n=17), and the PNF irradiation group (n=17). All subjects performed an active knee extension (AKE) test to assess for the lower extremity with a shortened hamstring. The static stretching group performed stretches by lifting their leg to the maximum extent (3 times, 30 seconds). The PNF hold-relax group performed maximal isometric contraction against the experimenter's resistance (3 times, 10 seconds). The PNF irradiation group performed maximum isometric contraction against the experimenter's resistance toward the direction of the body (5 times, 5 seconds). The pre and post-tests measured range of motion (ROM), pressure pain thresholds (PPT) and muscle tone. Results: There were significant differences in ROM and PPT between pre and post intervention in each group (p<0.05). There was a significant difference only in the ROM among groups (p<0.05). Post-hoc analysis showed that the changes in ROM occurred in the order of the PNF hold-relax group, static stretching group and PNF irradiation group (p<0.05). Conclusions: The findings of this study suggest that the PNF irradiation technique may improve ROM and may be used to improve ROM similar to other stretching techniques. Therefore, the PNF irradiation technique could be included in stretching programs and can be used as a suitable stretching method depending on the situation.

Background: Flexion-relaxation phenomenon (FRP) was a term which refers to a sudden onset of myoelectric silence in the erector spinae muscles of the back during standing full forward flexion. Hamstring muscle length may be related to specific pelvic and trunk movements. Many studies have been done on the FRP of the erector spinae muscles. However, no studies have yet investigated the influence of hamstring muscle flexibility on the FRP of the hamstring muscle and lumbopelvic kinematics during forward bending. Objects: The purpose of this study was to examine the flexion-relaxation ratio (FRR) of the hamstring muscles and lumbopelvic kinematics and compare them during forward bending in subjects with different hamstring muscle flexibility. Methods: The subjects of two different groups were recruited using the active knee extension test. Group 1-consisted of 13 subjects who had a popliteal angle under $30^{\circ}$; Group 2-consisted of 13 subjects who had a popliteal angel above $50^{\circ}$. The kinematic parameters during the trunk bending task were recorded using a motion analysis system and the FRRs of the hamstring muscles were calculated. Differences between the groups were identified with an independent t-test. Results: The subjects with greater hamstring length had significantly less lumbar spine flexion movement and more pelvic flexion movement. The subjects with greater pelvic flexion movement had a higher rate of flexion relaxation during full trunk bending (p<.05). Conclusion: The results of this study suggest that differences in hamstring muscle flexibility might cause changes in people's hamstring muscle activity and lumbopelvic kinematics.

Objective: This study evaluated the reliability and validity of the Nordic Hamstring Test (NHT) performed using a Wii Balance Board (WBB) for assessing eccentric hamstring strength, compared with a conventional isokinetic dynamometer (CSMI). Design: Cross-sectional validation study. Methods: Twenty-eight healthy young adults participated. Each performed three trials of the WBB-based NHT and eccentric knee extension testing using the CSMI at 60 °/s. Peak force and peak torque values were recorded and normalized to body weight. Reliability and validity were evaluated using standard statistical analyses. Results: The WBB-NHT demonstrated excellent within-session reliability. Peak force measured by the WBB-NHT showed significant positive correlations with peak torque obtained from the CSMI. A significant mean difference between the two measurement methods was observed. Conclusions: The WBB-based NHT provides reliable and valid measures of relative eccentric hamstring strength in healthy young adults. Its low cost and portability suggest that it may be a practical assessment tool in clinical and sports settings.

Purpose: To compare postural control strategies during single-leg stance between individuals with hamstring tightness and those with normal hamstring extensibility. Methods: Twenty healthy male adults in their 20s with right-leg dominance participated and were assigned to a hamstring tightness group (HT) or a control group based on the passive straight-leg raise (PSLR) performance. Postural control was assessed during single-leg stance (30 seconds, three trials, eyes open) using the LEGSys system (Biosensics, Cambridge, MA, USA). The outcome variables included mediolateral (ML) range, anteroposterior (AP) range, sway area, and sway velocity for center of mass (COM), hip angle, and ankle angle. Results: Compared to the control group, the HT group showed a significantly greater COM sway area and greater AP range and sway area of hip angle during single-leg stance (p<0.05). No significant between-group differences were observed for the remaining COM and hip variables (p>0.05). For ankle angle, no significant differences were observed in the ML range, AP range, sway area, or sway velocity (all p>0.05). Conclusion: The hamstring tightness was associated with selective alterations in postural control during single-leg stance, characterized by an increased COM sway area and greater hip kinematic excursions in the AP direction, while ankle kinematics remained comparable between groups. These findings suggest that the hamstring tightness may influence postural control strategies during the static single-leg stance by altering COM regulation and hip joint control rather than ankle-level adjustments.

Objective: The aim of this study is to investigate the effect of hamstring eccentric exercise on pain and functional activity in patients with chronic low back pain. Design: Randomized controlled trial Methods: Participants comprised 27 subjects with back pain persisting for 3 months. They were randomly assigned to the experimental group (Eccentric exercise: n=13) and the control group (Stretching: n=14). The experimental group performed gastrocnemius, iliopsoas, and quadratus lumborum stretching along with hamstring eccentric exercise, while the control group engaged in the same stretches along with hamstring stretching. The eccentric exercise for the hamstrings was Nordic curl exercise. Each group practiced for 1 hour a day, 3 times a week, for 4 weeks. Pain, disability index, balance, and hamstring length were measured. Results: Significant differences were observed in the comparison of changes in back pain, back disability index, and hamstring length before and after exercise within each group (p<0.05). The balance ability of the experimental group showed a difference before and after exercise (p<0.05), whereas no significant difference in the control group. There were no significant differences in back pain and hamstring length between the groups. Changes in back disability index and balance ability significantly increased in the experimental group compared to the control group (p<0.05). Conclusion: Hamstring eccentric exercise using Nordic curls has a positive effect on back pain, back disability index, balance ability, and hamstring length changes.

Objective: This study aimed to examine the relationship between hamstring muscle tension, muscle activation patterns, and flexion-relaxation during trunk flexion and extension. Design: Cross-sectional study. Methods: Twenty-five healthy adults were recruited and stratified into two groups based on hamstring tension; flexible (n = 13) and rigid (n = 12). Surface electromyography was used to quantify muscle activation in the trunk, hamstring, and gastrocnemius muscles during trunk flexion and extension. The primary outcome measure was the level of hamstring activation immediately after trunk flexion, which served as an indicator of flexion-relaxation. Results: Participants with elevated hamstring tension demonstrated significantly greater hamstring muscle activation immediately after trunk flexion (p < 0.05). Hamstring muscle activation and flexion-relaxation had a significant correlation, with significant differences in the flexion-relaxation ratio between both groups (p < 0.05). Conclusions: Hamstring tension was significantly correlated with muscle activation and flexion-relaxation during trunk flexion and extension. Hamstring tension may contribute to the development and persistence of lower back pain and offer deeper insights into the biomechanical mechanisms underlying back pain.

Objective: The purpose of this study was to examine the effectiveness of pelvic displacement when self-hamstring muscle stretches were applied to persons with low back pain. Design: Three-group pretest-posttest design. Methods: Forty persons with low back pain participated in this study. Pelvic tilt angle, hamstring flexibility, Quadruple Visual Analogue Scale (QVAS), Fear Avoidance Beliefs Questionnaire (FABQ), Korea version of the Oswestry Disability Index (KODI) and pelvic mobility were measured at pre-post. All participants were divided into either the pevic anterior tilt group (PAT group, n=12), pelvic midrange group (PMR group, n=18), or the pelvic posterior tilt group (PPT group, n=10). Self-stretching was performed using the pilates ring three times a week for a total of four weeks and the post-test was conducted and compared with the pre-test. Results: Hamstring flexibility, QVAS, KODI scores were significantly different compared to before the intervention (p<0.05). The changes in hamstring flexibility of the three groups were significantly different (p<0.05). Changes in KODI and FABQ results of the three groups were not significant. The pelvic posterior tilt range were significantly different in the PMR and PPT groups (p<0.05). The pelvic anterior tilt ranges showed significant differences after stretching in the PPT group (p<0.05). Conclusions: A large amount of change of hamstring flexibility, pelvic mobility of anterior and posterior tilt test in the PPT group was observed. Furthermore, therapists should consider pelvic displacement of the participant when applying intervention, which may, accordingly, have different effectiveness.

Background In clinical settings, a pressure biofeedback unit (PBU) is sometimes used to detect pelvic movement and retrain movement patterns during lower limb movement. Hamstring length influences changes in pelvic movement during passive straight leg raising (PSLR). Purpose To determine the relationship between pelvic motion and biofeedback pressure measured by a PBU during PSLR, and to identify changes in biofeedback pressure after hamstring stretching. Study design Cross-sectional study Methods Twenty participants with short hamstrings were recruited for this study. A three-dimensional motion analysis system and PBU were used to measure pelvic angle and biofeedback pressure during PSLR, respectively. The pelvis angle and biofeedback pressure were measured before and after hamstring stretching, increasing PSLR in 10-degree increments. Results There was a significant relationship between pelvic motion and biofeedback pressure (Pearson’s r=0.76, p<0.05). Linear regression equation using lumbopevic angle as an independent factor was as follows: Pressure of PBU=45.05+(3.35×angle of lumbopelvic motion) (R2=0.57, p<0.05). Biofeedback pressure decreased significantly between PSLR angles of 10?60° after hamstring stretching (p<0.05). The pelvic angle decreased significantly at PSLR angles of 50° and 60° after hamstring stretching (p<0.05). Conclusions Biofeedback pressure measured with a PBU can be used to assess pelvic motion during muscle length tests following hamstring stretching.

ABSTRACT Background Hamstring tightness is a major cause of low back pain (LBP). The active knee extension (AKE) test is frequently used to measure hamstring tightness in supine-positioned subjects. In patients with musculoskeletal pain, it is important to maintain the axis of rotation for accurate range of motion assessment. Purpose The purpose of this study was to investigate the intrarater test-retest reliability of an AKE test with belt-guided inferior gliding of the hip, which was designed to minimize excessive anterior-superior gliding of the hip in LBP patients with hamstring tightness. We also compared the range of AKE with versus without inferior gliding of the hip in this study population. Study design Reliability study. Methods Thirty-eight patients with LBP and hamstring tightness were recruited to this study. Hamstring tightness was measured in a supine AKE test, with and without inferior gliding of the hip, using the Smart KEMA device. Test?retest reliability was assessed by the intraclass correlation coefficient (ICC). Significant differences in the range of AKE between the groups were detected using a paired sample t-test. Results The hamstring flexibility tests with and without inferior gliding of the hip exhibited good to excellent test-retest reliability (ICC=0.89 for both). The range of AKE with inferior gliding of the hip was significantly less than that of AKE without inferior gliding of the hip. Conclusions Assessment of hamstring flexibility via an AKE test with inferior gliding of the hip is reliable when applied to patients with LBP; the range of AKE was lower in this test compared to those that do not incorporate inferior gliding of the hip.

Background: Although warm-ups before exercise are widely accepted, research on sex differences in improving hamstring flexibility is limited. Differences in the physical and physiological characteristics between males and females may result in different responses to warm-ups. Objects: This study aimed to examine sex differences in the effects of specific warm-up on hamstring flexibility. Methods: This study included 24 young adults with hamstring tightness. The participants performed five maximal knee extensions and flexions at 90° flexion of the hip, and the maximal knee extension angle was measured in real-time using a smartphone clinometer application. Results: The groups did not significantly affect the maximal knee extension angle but showed a significant effect for repetition (p = 0.002) and group-repetition interaction (p = 0.002). Males had no significant change in hamstring flexibility; however, females showed a significant increase in flexibility in the 5^th trial compared with the 1^st trial (p = 0.041). These results demonstrated sex-specific differences in flexibility improvement over time. Conclusion: The findings of this study suggest that specific warm-up can successfully improve hamstring flexibility in females. This may be due to various factors, such as muscle stiffness of the lower extremity, estrogen levels, and temperature sensitivity. In clinical settings, specific warm-up might be helpful for females who participate in sports or activities, such as running or jumping, which require a full range of motion in the hip and knee joints.