• Journal of the Korean Society of Physical Medicine
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• v.14 no.3
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• pp.1-11
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• 2019

PURPOSE: This study compared the changes in the range of motion (ROM ) on the knee joint according to three different isometric contraction intensities when applying Evjenth - Hamberg stretching (EHS) to the hamstring muscles of healthy subjects. METHODS: Forty eight healthy subjects aged between 20 and 39 years were allocated randomly to four groups; performing EHS at 10% maximum voluntary isometric contraction (MVIC) group, EHS at 50% MVIC group, EHS at 100% MVIC group, and control group (CG) pre-, and post-intervention. The flexibility of the hamstring muscles was evaluated using a digital goniometer for measuring the knee joint ROM motion. A Chattanooga stabilizer was used to adjust the MVIC intensity by 10%, 50%, and 100%, respectively. RESULTS: These results show that the pre- and post-intervention knee joint ROM were significantly different in all four groups (p<.05). The post-intervention knee joint ROM showed a significant difference between the 100% MVIC group and non-MVIC group (p<.05). The knee joint ROM difference between the pre- and post-interventions was similar in the 10% MVIC and 50% MVIC groups but significant differences were observed among the other groups (p<.05). CONCLUSION: EHS of the hamstring muscles was effective in improving the knee joint ROM with an isometric contraction intensity of 10%, 50%, or 100% MVIC, and of these, 100% MVIC was most effective.

• Physical Therapy Korea
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• v.28 no.1
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• pp.65-71
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• 2021

Background: The hamstring is a muscle that crosses two joints, that is the hip and knee, and its flexibility is an important indicator of physical health in its role in many activities of daily living such as sitting, walking, and running. Limited range of motion (ROM) due to hamstring tightness is strongly related to back pain and malfunction of the hip joint. High-frequency diathermy (HFD) therapy is known to be effective in relaxing the muscle and increasing ROM. Objects: To investigate the effects of HFD on active knee extension ROM and hamstring tone and stiffness in participants with hamstring tightness. Methods: Twenty-four participants with hamstring tightness were recruited, and the operational definition of hamstring tightness in this study was active knee extension ROM of below 160° at 90° hip flexion in the supine position. HFD was applied to the hamstring for 15 minutes using the WINBACK device. All participants were examined before and after the intervention, and the results were analyzed using a paired t-test. The outcome measures included knee extension ROM, the viscoelastic property of the hamstring, and peak torque for passive knee extension. Results: The active knee extension ROM significantly increased from 138.8° ± 9.9° (mean ± standard deviation) to 143.9° ± 10.4° after the intervention (p < 0.05), while viscoelastic property of the hamstring significantly decreased (p < 0.05). Also, the peak torque for knee extension significantly decreased (p < 0.05). Conclusion: Application of HFD for 15 minutes to tight hamstrings immediately improves the active ROM and reduces the tone, stiffness, and elasticity of the muscle. However, further experiments are required to examine the long-term effects of HFD on hamstring tightness including pain reduction, postural improvement around the pelvis and lower extremities, and enhanced functional movement.

• The Journal of Korean Physical Therapy
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• v.28 no.1
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• pp.59-63
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• 2016

Purpose: The objective of this study was to identify determine the effect of the strap height on muscular activity of trunk and lower limbs muscles during bridging exercise with a sling. Methods: The subjects of the study were 17 healthy male adults. In order to For measurement of muscular activity, body surfaces electrodes were placed on areas including erector spinae, multifidus muscles, gluteus maximus, and hamstring and the results was were recorded based on three different heights of strap, which are Levels 1, 2, and 3. Results: The muscular activities in erector spinae, multifidus muscle, and gluteus maximus were significantly different in at all three heights (p<0.05)., Level 3 showed the highest the compared to Levels 1 and 2. In hamstring muscle, there was significant difference in levels 1 and 2, also and levels 1 and 3 (p<0.05),. Bbut there was no significant difference between 2 and 3. The ration of muscular activities in multifidus muscles/erector spinae and gluteus maximus/hamstrings were significantly different for all three strap heights (p<0.05). Also, Level 3 showed higher than 1 or 2. Conclusion: The results of this study suggests to adjustment of the level III, that which has high activity level of multifidus and gluteus maximus affecting trunk stability during bridging exercise using a sling.

• Physical Therapy Rehabilitation Science
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• v.11 no.3
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• pp.329-334
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• 2022

Objective: Low back pain (LBP) is a symptom that accounts for a large proportion of musculoskeletal pain. Among them, non-specific LBP (NSLBP) means that the pathological cause is unknown, and belongs to the most common LBP. Studies on the mechanism of muscle control in LBP are insufficient, and quantitative studies are needed. Design: Observational cross-sectional study design Methods: A Thirty participants with NSLBP symptoms were enrolled, and their pressure pain thresholds (PPT) and muscle and fat thickness were measured. Participants measured the paraspinal muscles (PM) of the thoracic and lumbar spine and medial hamstring (semitendinosus) on the dominant and non-dominant sides in the prone position. Results: Among the variables that were significant in the correlation analysis, PM of the thoracic and lumbar spine showed a significant relationship in the PPT ([thoracic spine PM]=1.141+0.912 [lumbar spine PM]). Also, there was a significant relationship between the lumbar spine PM in the PPT and the thoracic spine PM in the muscle thickness ([lumbar spine PM of PPT]=4.057+0.117 [thoracic spine PM of muscle thickness]) Conclusions: Although there was no muscle imbalance according to the dominant and non-dominant side, there is a correlation between the pressure pain threshold and the muscle thickness between the paraspinal muscles of the thoracic spine and the lumbar spine.

• Physical Therapy Korea
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• v.30 no.1
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• pp.8-14
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• 2023

Background: Excessive hamstring (HS) activation due to the weakness of the gluteus maximus (GM) causes pain in the hip joint. A single-leg deadlift is a hip extensor exercise, especially GM, that includes functional movements in daily life and complex multi-joint training. In single-leg deadlift, the muscle activity depends on the forward trunk lean angle, and it's necessary to study which muscles are used dominantly depending on the angle. Objects: The purpose of this study was to compare the effect on the muscle activity of the GM and HS during single-leg deadlift according to different forward trunk lean angles and the ratio of the GM vs HS (GM/HS). Methods: Twenty-one healthy female participants were recruited. The muscles activities of the GM, HS and the GM/HS ratio were measured through electromyography during single-leg deadlift according to three condition of forward trunk lean angles (30°, 60°, and 90°). Results: The GM and HS activities significantly differed among three conditions (p < 0.05). GM/HS ratio was significantly higher at 30° and 60° of forward trunk lean compared to 90°. Moreover, the GM activity was significantly higher at 60° of forward trunk lean than at 30° (p < 0.05). Conclusion: The single-leg deadlift at 60° of forward trunk lean is a proper GM muscle strengthening exercise.

• PNF and Movement
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• v.13 no.1
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• pp.31-37
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• 2015

Purpose: The purpose of this study is to compare changes in the flexibility of hamstring muscles which are relaxed on suboccipital muscle through suboccipital muscle inhibition and combination technique. Methods: Thirty sample subjects (16 male and 14 female) were randomly divided into an experimental group (n=15) and a control group (n=15). 1. Suboccipital muscle inhibition: Suboccipital muscles of the patients were placed on a bed. The occipital region was placed on a therapist's fingers, and the posture was maintained for three minutes before remeasurement. 2. Treatment with combination technique (body bolster and wooden pillow): Wooden pillows were placed where the participants could relax the posterior arch of the atlas; additional body bolsters were also placed to avoid high pressure, and the treatment was maintained for three minutes before remeasurement. Results: There was a statistical difference in finger floor distance (FFD) and straight leg raise (SLR) results for those treated with SMI (P<0.05). There was no statistical difference in FFD and SLR results for those treated with the combination technique (P>0.05). Conclusion: Between the two intervention methods; the suboccipital muscle inhibition technique was more effective in increasing the flexibility of subjects with a shortened hamstring than was the combination technique.

• Journal of Korean Physical Therapy Science
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• v.27 no.1
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• pp.9-17
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• 2020

Background: This study aimed to examine the repeatability of hamstring strength during maximal voluntary contractions (MVCs) and to examine the sex difference. Design: Quasi-experiment design. Methods: The study recruited 23 healthy young individuals as participants. Hamstring flexibility was measured before and after MVCs by active knee extension test. Five trials of MVCs were performed, and hip extension forces were measured using a strain gauge during MVCs. Repeatability was confirmed by intraclass correlation coefficient (ICC) and coefficient of variation, and the difference between male and female participants was confirmed by independent samples t-test. Results: The forces measured during MVCs were significantly different between men and women over five trials. We observed the minimum and maximum force production at the first and fifth trial of MVCs in both men and women. Excellent to moderate reliability of the hamstring strength during MVCs was found in men (ICC range, 0.70-0.98) and women (ICC range, 0.66-0.90). There was no significant difference in hamstring flexibility between men and women. Conclusion: In clinical settings, we recommend excluding the first trial of MVCs in both men and women. Additionally, performing at least three trials of MVCs would be useful to improve the reliability of the baseline measures in women.

• PNF and Movement
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• v.19 no.1
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• pp.1-8
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• 2021

Purpose: The purpose of this study was to determine how the position of tibial rotation affects peak force and hamstring muscle activation during isometric knee flexion in healthy women. Methods: Seventeen healthy women performed maximum isometric knee flexion at 30˚ with three tibial rotation positions (tibial internal rotation, neutral position, and tibial external rotation). Surface electromyographic (EMG) activity was recorded from the medial hamstring (MH) and lateral hamstring (LH) muscles. The strength of the knee flexor was measured with a load-cell-type strength-measurement sensor. Data were analyzed using one-way repeated analysis of variance. Results: The results showed that MH and LH activities and peak force were significantly different among the three tibial rotation conditions (p < 0.01). The post-hoc comparison revealed that the MH EMG activity in tibial neutral and internal rotation positions were significantly greater than tibial external rotation (p < 0.01). The LH activity in tibial external rotation was significantly greater than the tibial neutral position and internal rotation (p < 0.01). The peak force of the knee flexor was also greater in the external tibial rotation position compared with the tibial neutral and internal rotation positions (p < 0.01). Conclusion: Our findings suggest that hamstring muscle activation could be changed by tibial rotation.

• Journal of Korean Physical Therapy Science
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• v.28 no.1
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• pp.76-84
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• 2021

Background: In clinical practice, active knee extension (AKE) test has been widely used to measure hamstring flexibility. During the AKE test, the knee extension is repeated six times. The first five repetitions are considered as warm-up, and the sixth is used as baseline. In order to accurately measure the subject's inherent flexibility, warm-up trials have been proposed as mentioned above; but currently, the evidence is insufficient. Design: Cross-sectional study. Methods: Forty-three healthy adults participated in this study. The AKE was performed slowly after flexing the hip and knee joints by 90° in a supine position. The knee was extended as far as could be done without causing discomfort or pain. When reaching the end range, knee flexion was performed without stopping. As per standard protocol, the subjects performed the knee extension six times. Results: There was no significant difference between the AKE value in the first trial with those in the other five trials. During the repetitions, the average value in the group with higher flexibility tended to decrease and the Intraclass correlation coefficient gradually decreased. Conclusion: Successive repetitions of the AKE test can misrepresent an individual's inherent hamstring flexibility. In order to avoid a decrease in hamstring flexibility, it is strongly recommended that individuals with high initial hamstring flexibility avoid unnecessary repetitions of the AKE test.

• Physical Therapy Korea
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• v.30 no.4
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• pp.275-280
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• 2023

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.