• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.67-73
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• 2010

The purpose of this study was to compare the differences in kinematic and kinetic parameters of the ankle and knee joint according to three landing direction(central, left, right). Fifteen collegiate male athletes(age: $22.7{\pm}3.5$ years, height: $174.9{\pm}7.1\;cm$, weight: $69.4{\pm}6.7\;kg$) with the right leg as dominant were chosen. The subjects performed series of drop landings in three directions. In terms of the three different landing directions, plantar flexion was the greatest during the central drop landings. For each initial contact of the landing direction, plantar flexion of the ankle was greatest at the central drop landing, inversion of the ankle was greatest at the right landing and valgus of the knee was greatest at the left drop landing. Regarding the peak force, the greatest was at the 1st peak force during the central drop landing. For the time-span of the 2nd peak force and the 2-1 peak force, both right sides resulted as the greatest. Therefore, with the appropriate training in landing techniques and developing neuromuscular training for proprioception by taking the injury mechanisms on ankle and knee during drop landings into account, it will assist in preventing such injuries.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.15-22
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• 2011

Purpose: The purpose of this study was to investigate the relationship between hip abductor muscle strength and lumbar instability in patients with chronic low back pain. Methods: Fifty-two female patients were recruited for this study. The patients' history was recorded and was used to determine the general characteristics of the female complaints. The women were additionally examined to determine whether the level of pain was characteristic of patients with chronic lumbar instability. The following tests were also carried out in the subjects during the examination: 1) the prone instability test. 2) the test for aberrant movement patterns during lumbar flexion test. 3) the straight leg raising test. 4) posterior-to-anterior mobility test, and 5) the test for age and strength of the hip abductor muscle following assessment of the dominant side. In particular, hip abductor muscle strength was evaluated using a dynamometer. Results: The test results showed that the number of positive responses for the five types of lumbar instability tests performed, was significantly related to the strength of the hip abductor muscle. The average hip abductor muscle strength in total subjects was $72.89{\pm}7.66N$, whereas the average hip abductor muscle strength in subjects who showed positive responses to more than four out of the five tests, was $44.70{\pm}5.79N$. Conclusion: The results demonstrated that the hip abductor muscle strength and lumbar instability were negatively correlated. The lower was the strength of the hip abductor muscle, the higher was the possibility of lumbar instability.

• Physical Therapy Korea
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• v.24 no.1
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• pp.9-18
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• 2017

Background: Short foot exercise (SFex) is often prescribed and performed in the sport and rehabilitation fields to strengthen intrinsic foot muscles. However, SFex is difficult to perform because of lack of feedback methods. Objects: The aim of this study was to compare the effects of SFex with and without electromyography (EMG) biofeedback on the medial longitudinal arch (MLA) of healthy individuals who maintained a static standing position. Methods: All participants (14 males and 12 females) were randomly divided into two groups (biofeedback and non-biofeedback groups). The EMG activity of the abductor hallucis (AbdH) and tibialis anterior (TA) and the MLA angle on the dominant leg side were measured with the participant in the standing position in the pre- and post-intervention conditions. The intervention session consisted of 15 minutes of SFex with (biofeedback group) or without (non-biofeedback group) EMG biofeedback. The groups were compared using two-way repeated measures analysis of variance. Results: The post-intervention activities of the AbdH muscle (p<.05) and the AbdH/TA ratio (p<.05) were significantly greater in the biofeedback group than in the non-biofeedback group. The activity of the TA (p<.05) and the MLA angle (p<.05) in the biofeedback group were significantly lower in the post-intervention condition than in the pre-intervention condition. Conclusion: The present findings demonstrate that the combination of SFex and EMG biofeedback can effectively facilitate the muscle activity of the AbdH and strengthen the medial longitudinal arch.

• Physical Therapy Korea
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• v.24 no.2
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• pp.19-26
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• 2017

Background: To improve lumbo-pelvic stability, passive support devices (i.e., a pelvic belt) are recommended clinically. Nevertheless, to understand the influence of passive support on lumbo-pelvic stability, it is necessary to examine the influence of a pelvic belt on the abdominal and hip abductor muscles. Objects: To examine the effects of a pelvic belt on the forces of the hip adductor and abductor muscles and activity of the abdominal muscles during isometric hip adduction and abduction. Methods: This study recruited 14 healthy men. All subjects performed isometric hip adduction and abduction with and without a pelvic belt in a neutral hip position. Load cells, wrapped with a non-elastic belt, were placed above the medial and lateral malleoli of the dominant leg to measure the muscle forces of the hip adductors and abductors, respectively. The forces of the hip adductors and abductors were measured using a load cell during isometric hip adduction and abduction, while the electromyographic activities of the bilateral rectus abdominis, internal oblique, and external oblique muscles were measured. Results: The forces generated by the hip adductors and abductors were significantly greater with the pelvic belt than without (p<.05). No significant differences in abdominal muscle activities between the two conditions were found (p>.05). Conclusion: These findings suggest that use of a pelvic belt could lead to effective strengthening exercise of hip muscles in individuals with sacroiliac joint pain.

• Physical Therapy Korea
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• v.26 no.3
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• pp.84-90
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• 2019

Background: Ankle evertor muscles are important for preventing lateral ankle sprain. Since, the evertor muscles cross the ankle and toe joints, the position at which the ankle evertor muscle strength is measured is important. However, no studies have previously investigated the effect of ankle and toe positions on the strength of the ankle evertor muscle. Objects: This study is aimed to determine the effect of various ankle and toe joint positions on the strength of the ankle evertor muscles in healthy subjects. Methods: Eighteen healthy subjects participated in this study. Isometric ankle evertor strength of the dominant leg was determined in each subject in different ankle and toe positions (dorsiflexion (DF) with toe extension (TE), DF with toe flexion (TF), plantar flexion (PF) with TE, and PF with TF). A 2 by 2 repeated analysis of variance (ANOVA) was used to determine the difference in the evertor strength between the ankle positions (PF and DF) and toe positions (TE and TF). Results: The results indicate that there was no significant ankle position by toe position interaction effect (p=.83). However, the ankle evertor strength was significantly increased in the ankle DF position than in the PF position (p<.01), and the ankle evertor strength during eversion with TE was significantly higher than eversion with TF (p<.01). Conclusion: The findings of this study suggest that clinicians should consider the ankle and toe positions when measuring the muscle strength and during performance of selective muscle strengthening exercises of the ankle evertor muscles.

• Journal of Korean Physical Therapy Science
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• v.26 no.1
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• pp.45-53
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• 2019

Background: The purpose of present study was to examine the effect of ultrasound therapy and static stretching on hamstring length and balance. Design: Randomized Controlled Trial. Methods: A total of 30 adults in S college, Seongnam city, Gyeonggi-do, between the ages of 20-30 were randomly assigned to two groups. Group 1 (n=15) had ultrasound therapy, called US group. Group 2 (n=15) had static stretching, called SS group. Measurements were taken prior to starting the program and after completing the experiment using Finger to floor test and Active knee extension test to get the results of hamstring flexibility and the ability of static balance. Paired t-test was used to compare each group pre-test values to post-test values and to compare US post-test values to SS post-test values on PASW 18.0. Results: 1) Both hamstring SS group and US group had significant increase (p<.05) in Finger to floor test and Active knee extension test. 2) Dominant leg standing had significant change (p<.05) only in US group. 3) There was no significant difference between US group and SS group. Conclusion: Results showed that US group and SS group had an effect on changes in hamstring length (p<.05). However, they did not show a significant increase in static balance. Further effective studies on hamstring SS group and US group were needed based on this examination.

• Physical Therapy Rehabilitation Science
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• v.8 no.3
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• pp.125-133
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• 2019

Objective: To compare the postural control between non-specific chronic low back pain (NSCLBP) subgroups and healthy people during dynamic balance performance using a modified Star Excursion Balance Test (mSEBT). Design: Cross-sectional study. Methods: Eighteen NSCLBP subjects (9 active extension pattern [AEP], 9 flexion pattern [FP]), and 10 healthy controls were enrolled in this study. All subjects performed mSEBT on their dominant leg on a force plate. Normalized reach distance and balance parameters, including the center of pressure (COP) displacement and velocity, were recorded. Results: There were significant differences in mean reach distances in both posterolateral and posteromedial (PM) reach directions between AEP and healthy subjects (p<0.001) and between FP and healthy subjects (p<0.001). However, there were no significant differences among the three groups in the anterior reach direction. Also, the results showed no significant differences in mean COP variables (velocity and displacement) between pooled NSCLBP and healthy subjects. However, the subjects were reclassified into AEP, FP and healthy groups and the results showed a significant difference in mean COP velocity in the PM direction between AEP and FP subjects (p=0.048), and between AEP and healthy subjects (p=0.024). Conclusions: The findings in this study highlight the heterogeneity of the individuals with NSCLBP and the importance of identifying the homogenous subgroups. Individuals with AEP and FP experience deficits in dynamic postural control compared to healthy controls. In addition, the findings of this study support the concept of the Multidimensional Classification System.

• Physical Therapy Rehabilitation Science
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• v.12 no.1
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• pp.1-11
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• 2023

Objective: This study aimed to investigate the effects of squat posture, band position, and contraction type on the muscle activity of the hip abductors during resisted lateral band walking. Design: A cross-sectional survey study Methods: 24 healthy male subjects were recruited, and surface electromyography was used to measure the muscle activity of the gluteus maximus, gluteus medius, and tensor fascia lata of the dominant leg during lateral walking exercises. Resistance bands were applied to the knees, ankles, and feet in semi-squat and squat postures, and exercises were randomly performed under six different conditions. Results: The results showed significant differences in muscle activity in the gluteus maximus, gluteus medius, and tensor fascia lata according to posture, band position, and contraction type (p<0.05). The muscle activity of the hip abductors increased in the squat posture and with the band placed on the distal joint compared to the proximal joint (p<0.05). Additionally, muscle activity was higher in the eccentric contraction phase than in the concentric contraction phase (p<0.05). Contrary to previous studies, moving the resistance band from the ankle to the foot increased the muscle activity of the tensor fascia lata while the activity of the gluteus maximus and gluteus medius also increased. Conclusions: According to the results, squat posture with a resistance band placed on the feet and using an eccentric contraction phase were found to be the most effective methods for strengthening the hip abductors.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.414-420
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• 2022

Objective: In this study, the test-retest reliability and validity were presented to evaluate the usability of isokinetic rehabilitation equipment for the knee joint. Design: Cross-sectional design, reliability & validity study. Methods: Thirty healthy adults participated in the study. A CSMI dynamometer was used as a standardized measuring device to present the validity of the equipment. It was measured based on the dominant leg. The average peak torque value was selected as the measurement variable. After the measurement, a questionnaire was conducted on safety, satisfaction, and performance through the usability evaluation questionnaire. Results: The knee joint isokinetic rehabilitation equipment showed high reliability with Intraclass Correlations Coefficients (ICC) =0.883~0.956. In order to check the validity of the equipment, the 95% confidence interval of the mean difference limit was confirmed by the Bland & Altman plot. As a result, all three angular velocities showed a smaller confidence interval in the flexion than in extension. There were less than 10 plots that were not included in 2 Standard Deviation (SD) between all measurements. As a result of the usability evaluation questionnaire, the average of the safety domain(4.9±0.4), satisfaction domain(4.1±0.8), performance domain(4.3±0.8). Conclusions: If the product is improved by supplementing the items identified in the usability evaluation process, it is judged that it can be used as a useful device in various knee joint rehabilitation fields.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.183-190
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• 2015

Objective : Walking with a Material handling is an activity frequently undertaken by agricultural workers in Korea, due to the nature of their work. This study aimed to investigate differences in biomechanical variables according to the mechanical alignment of the lower limbs when walking with a heavy load, and to use this as basic data in the design of various working environments to reduce the skeletomuscular burden on the knee joint. Method : The study subjects comprised of 22 right-foot dominant adult men and women aged between 20 and 23 years. The subjects were divided into a varus or valgus group according to the mechanical alignment of the lower limb by using radiographic findings. The subjects walked without any load and with a load of 10%, 20%, or 30% of their body weight held in front of them. The Kwon3d XP program was used to calculate biomechanical variables. Results : The flexion/extension moment of the knee joint showed a decreasing trend with increased load, irrespective of the mechanical alignment of the lower limb, while the varus group did not show normal compensatory action when supported by one leg at the point of maximum vertical ground reaction force. In addition, in terms of the time taken, subjects showed no difficulties in one-foot support time up to 20%/BW, but at 30%/BW, despite individual differences, there was an increase in single limb. The increased load resulted in a decrease in the ratio of standing phase to ensure physical stability. The valgus group showed a trend of increasing the stability of their center of mass with increasing load, through higher braking power in the early standing phase. Conclusion : In conclusion, although there was no statistical difference in biomechanical variables according to the mechanical alignment of the lower limbs, the varus group showed a more irregular walking pattern with a Material handling than the valgus group, partially proving the association between lower limb alignment and walking with a Material handling.