• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.585-590
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• 2022

Objective: The purpose of this study was to investigate the effects of neuromuscular training of ballet dancers with chronic ankle instability on ankle stability and posture controlability. Design: A randomized controlled trial. Methods: A total of Thirty-twoyoung female ballet dancers with chronic ankle instability have voluntarily participated in the study. The participants were randomized to the neuromuscular training group(n₁=11), elastic resistance squat group(n₂=11), and control group(n₃=10). The intervention was applied to a total of 18 exercises per six weeks and conducted in each group for one hour a day, three times a week. All subjects were evaluated for Cumberland ankle instability tool(CAIT), static balance at before-after intervention. Results: In the comparison of the effects within the groups, the effect of the intervention on CAIT and posture control was significantly increased in the neuromuscular training group and elastic resistance squat group (p <0.05). In the comparison of the effects between the groups, the neuromuscular training group, and elastic resistance squat group were found to significantly increase more than the control group (p <0.05). The effect of ankle stability is similar in neuromuscular training and elastic resistance squat training, neuromuscular training is more effective in improving posture control rather than elastic resistance squat training. Conclusions: When planning a rehabilitation training program for a ballet dancer with chronic ankle instability, neuromuscular training can be applied as an intervention method to improve ankle stability and posture control ability.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.9-17
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• 2024

Objective: The purpose of this study is to apply 8-week velocity-based training to domestic professional athletes and the kinematic and kinetic analysis of the 1-RM improvement of back squat and power clean, which can represent strength-power ability, to verify the effectiveness of velocity-based training in Korea and to establish a basic basis. Method: The subjects who participated in this study were 10 professional athletes from K University (age: 21.40 ± 0.97 yrs., height: 179.90 ± 3.54 cm., body mass: 71.298 ± 2.98 kg). All subjects performed back squat and power clean 1-RM before and after 8-weeks of velocity-based training. A 3-dimensional motion analysis with 8 infrared cameras and 4 channels of EMG was performed in this study. A paired t-test was used for statistical verification. The significant level was set at α=.05. Results: Both Back squat and Power Clean 1-RM showed statistically significant increases (p<.05). In the case of back squat, there was no statistically significant difference in both kinematic and kinetic variables (p>.05). In the case of Power Clean, only the quadriceps of Phase 1 showed a statistically significant decrease (p<.05). Conclusion: Domestic professional athletes can improve their strength-power ability through velocity-based training, and such training for at least 8-weeks is considered a way to improve their performance.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.128-136
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• 2023

Objective: The aim of this study was to investigate the effect of an 8-week closed kinetic chain typed Reformer and Chair Pilates exercise on static and dynamic lower limb alignment for healthy female adults. Method: Ten healthy young female adults without musculoskeletal injury history in last 6 months (Age: 29.3 ± 3.5 yrs., Height: 165 ± 3.4 cm, Body mass: 58.2 ± 5.4 kg) participated in this study. All participants asked to join the 8-week closed kinetic chain typed Reformer and Chair Pilates exercise, and the program was conducted for 60 minutes twice a week. Participants were asked to be measure a static Q-angle and performed free squat one week before and after the program. A 3-D motion analysis with 8 infrared cameras and 5 channels of EMG was executed in this study. The effectiveness of the training was evaluated by paired t-test, and the significance level was set at .05. Results: A significantly decreased in internal rotation angles was found at hip joint during free squat after the training. Also, significantly decreased in lateral rotation angles were found at knee and ankle joint during free squat after training. Finally, significantly decreased in muscle activations were found at adductor longus and peroneus longus during free squat after training. Conclusion: From results of our study, it is concluded that an 8-week closed kinetic chain typed Pilates exercise positively effect on lower limb alignment during dynamic movement.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.1
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• pp.23-31
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• 2021

PURPOSE: This study was conducted to identify the effects of altering foot position on quadriceps femoris including vastus medialis obliques (VMO), vastus lateralis (VL) and rectus femoris (RF) activation during wall squat exercises. METHODS: All subjects (n = 15) were selected and randomly performed three kinds of wall squats: 1) GWS (General Wall Squat), 2) WSS1/4 (Wall Squat Short 1/4), and 3) WSS1/2 (Wall Squat Short 1/2). Each subject completed all three kinds of wall squatting exercises at three different times and recorded the muscle activity data of vastus medialis obliques, vastus lateralis and rectus femoris. RESULTS: Compared with GWS exercise, VMO and RF muscle activity significantly increased under WSS1/2 exercise (p < .05), while only RF muscle activity significantly increased under WSS1/4 exercise (p < .05). CONCLUSION: The results of the present study indicate that moving the foot toward the wall during wall squats has a positive effect on quadriceps activation. The exercise of wall squat short can not only be used as the lower limb muscle strengthening training for normal people, but also as the recovery training for patellofemoral pain syndrome patients in the rehabilitation stage. Besides, Anterior cruciate ligament patients can also try this exercise according to the advice of doctors and therapists.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.37-43
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• 2018

Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.3
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• pp.1-11
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• 2023

Background: The aim of this study was to compare the effects of squat training on an unstable support surface with different knee flexion angles on the balance ability of normal adults balance ability. Methods: 41 university students in their 20s attending N University in Cheonan, Chungcheongnam-do were divided into a 45-degree knee-bending squat training group and a 90-degree knee-bending squat training group. The groups trained on an unstable support surface 20 minutes per day, 3 times a week, for a total of 4 weeks. Results: Changes in static balance ability were not significant within and between the groups for both the sway distance and sway area in the eyes open and eyes closed states (p<.05). The changes in dynamic balance ability were significant in the forward, leftward, and rightward angles in both groups at the limit of stability (p<.05), but not significant in the backward angle (p>.05), and the comparison between groups was not significant (p>.05). Conclusion: No significant difference between static balance-related variables within and between the groups was found. Significant changes in dynamic balance-related variables within the groups were found but not between the groups. Therefore, in future studies, it is considered necessary to study various ages and differentiated intervention periods, such as young adults and the population of elderly people, with sufficient intervention periods to affect balance ability.

• Physical Therapy Rehabilitation Science
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• v.8 no.2
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• pp.86-92
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• 2019

Objective: The purpose of this study was to compare the effects of performing squats and kneeling squats on trunk and lower extremity muscle activity in persons with stroke. Design: Cross-sectional study. Methods: Ten persons with stroke (3 male and 7 female) were recruited. The subjects were instructed to randomly perform the 4 different squat conditions: squat with 30 degrees of knee flexion, squat with 60 degrees of knee flexion, squat with 90 degree of knee flexion, and the kneeling squat. During the squat performance, surface electromyograms (sEMG) was used to assess muscle activity of the erector spinae (ES), gluteus maximus (Gmax), gluteus medius (Gmed), and biceps femoris (BF) muscles. Results: Muscle activation of the ES and BF were significantly increased with the kneeling squats compared to the general squats with 30 degrees and 60 degrees of knee flexion (p<0.05), and muscle activation of the Gmax and Gmed were significantly increased with the kneeling squats compared to all other squat conditions (p<0.05). Conclusions: The results suggest that the kneeling squat is an effective exercise to strengthen the proximal muscles of the lower extremities. Rather than applying a difficult general squat to the stroke population, the kneeling squat may be applied as a safer method for training the proximal muscles.

• The Journal of Korean Society for Neurotherapy
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• v.22 no.3
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• pp.7-10
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• 2018

Purpose The purpose of this study was to investigate the difference of brain activity during action observation training and image training throughout EEG. Methods This study was participated 1 healthy college student without mental illness or cognitive impairment. The subject was randomly selected from university students and was interested in participating in the experiment. The purpose of this study was to investigate the visual and auditory stimuli (action observation) and brain image training. Results The results of our study, EEG value measured o.1 during resting. But brain activity changed to 0.3 during action observation. Finally, it changed to .05 after brain image training. Conclusion EEG measurement results were showed that after watching the Ball squat video, Brain activity increased.

• The Journal of Korean Physical Therapy
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• v.28 no.2
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• pp.95-100
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• 2016

Purpose: The purposes of this study were to examine muscle activities of trunk and lower limb during squat and 108 bows exercises and to provide objective data for establishing a training method for improving muscle strength of trunk and lower limb. Methods: Twenty normal healthy subjects participated in this study. Each exercise was divided into five periods. Muscle activities of trunk and lower limb in each period of both 108 bows and squat exercises were measured and analyzed by independent t-test. Results: In starting, mid-flexion, mid-extension, and end period muscle activities obtained from 108 bows exercise were significantly higher than those from squat exercise. However, in the final flexion period, muscle activities of multifidus, elector spinae, rectus femoris, biceps femoris, and tibialis anterior from squat exercise were significantly higher than those from bow exercise. Conclusion: In this study, high muscle activities in most muscles of trunk and lower limb were observed from all periods of 108 bows exercise except the final flexion period. Therefore, it is likely that 108 bows exercise rather than squat exercise is more suitable for high strength exercise to improve muscle strength of trunk and lower limb and thus will be applicable for strengthening muscles of trunk and lower limb of patients.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.691-701
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• 2017

The barbell squat is a fundamental physical exercise for strengthening the lower body and core muscles. It is an integral part of training and conditioning programs in sports, rehabilitation, and fitness. In this paper, we proposed a virtual test framework for squat exercises using a Smith machine to simulate joint torques and muscle forces, based on an integrated product-human model and motion synthesis algorithms. We built a muscular skeletal human model with boundary conditions modeling the interactions between the human body and a machine or the ground. To validate the model, EMG, external forces, and squat motions were captured through physical experiments by varying the foot position. A regression-based motion synthesis algorithm was developed based on the captured squat motions to generate a new motion for a given foot position. The proposed approach is expected to reduce the need for physical experiments in the development of training programs.