• 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.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.463-471
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• 2019

The purpose of this study was to investigate the effect of muscle imbalance on motion of back squat. The isokinetic muscle strength of the 8 subjects was recorded for the knee flexion/extension by the cybex 770 dynamometer. Each subject performed 3 back squats with the long barbell with an intensity of 25% body weight(BW), 50%BW, 100%BW, 125%BW. During the back squat through the recorded kinematic data the subjects' maximum flexion and extension knee angle, center of mass displacement and V-COP were calculated for evaluation of the stability of the movement. For the statistical analysis independent t-test was used. Knee flexion angle and COM displacement are dominated by the reciprocal muscle ratio. V-COP factor was dominated by bilateral extension deficit. Based on the results we can know that as the intensity of the squat increased to a level control was difficult because the muscles' imbalance influenced the movement.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.172-180
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• 2022

Objective: The purpose of this study was to investigate the effects of squat exercises using elastic bands of ballet dancers on muscle activity, arabesque angle, and static balance of ballet dancers during arabesque posture. Design: A randomized controlled trial Methods: A total of 25young female ballet dancer svoluntarily participated in the study. The participants were randomized to the elastic resistance squat group(n₁=13) and body squat group(n₂=12). The squats exercise was applied to a total of 12 exercises per four weeks and consisted of 15 times per one set in one to two weeks, 4 sets in three to four weeks. All subjects were evaluated muscle activity, arabesque angle, and static balance during arabesque posture at before-after intervention. All participants were measured muscle activity, arabesque angle, and static balance during arabesque posture at before-after intervention. Results: Elastic resistance squat group and body groups showed a significant increase in the muscle activity, angle, and static balance ability during arabesque posture(p<0.05). In the comparison between the groups, the elastic resistance squat group showed a significant increase in muscle strength, angle, and static balance during arabesque posture (p<0.05). The results showed that the elastic resistance squat exercise was more increased than the body squat exercise in all variables (p<0.05). Conclusions: Therefore, when planning a training program for a ballet dancer, the elastic resistance squat movement can be applied as an exercise method to improve the muscular performance and balance ability of the ballet dancer.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.2
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• pp.169-176
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• 2022

Purpose : The purpose of this study is to investigate the effect of squat, bracing and aerobic exercise on lung function, which is known to be effective for strength training, on lung function. Methods : The study was conducted with 33 students from Busan K university. Eleven students were assigned to squats, bracing, and aerobic exercise, six weeks three times a week. In order to measure lung activity, pony Fx manufactured the change amount of FVC (forced vital capacity), FEV₁ (Forced expiratory volume at one second), and FEV₁/FVC % (forced vital capacity/forced expiratory volume at one second) was analyzed after inputting the information of experimental group A and B controls. As a method of measurement, the difference between the three groups was analyzed using repeated ANOVA. Results : As a result of analyzing the effects of squat, bracing, and aerobic exercise for 6 weeks, all values of FVC, FEV₁, FEV₁/FVC % were increased from 0 weeks to 6 weeks except FEV₁/FVC %. There was no significant difference in FVC from week 3 to week 6. In the squat, bracing, and aerobic exercise, the changes in spirometry showed that the FVC, FEV₁, and FEV₁/FVC % values in bracing exercise were significantly increased with time than before exercise. As a result of analyzing the changes in the spirometry of squat, bracing, and aerobic exercise, the FVC, FEV₁, FEV₁/FVC % values in the squat exercise showed statistically significant difference according to the period, but the lowest increase among the three groups. Conclusion : In conclusion, aerobic, bracing and squat exercises all had a significant impact on improving lung function. Therefore, even without aerobic exercise, squat or bracing exercise alone can be expected to improve lung function.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.1-9
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• 2022

Purpose : The purpose of this research is to propose a more efficient exercising method by measuring and comparing the movement of center of pressure (COP) while hemiplegic stroke patients perform kneeling squat exercise and squat exercise. Methods : 17 hemiplegic stroke patients were instructed to perform kneeling squat exercises and squat exercises, and the research was designed as a cross-over study. For data collection, a pressure distribution measurement platform (PDM) was used to measure the movement area, length, speed, and distance from the center of the X-axis of center of pressure. The data was then analyzed through a paired t-test. Results : Kneeling squat exercises have been found to have a significantly smaller center of pressure movement area compared to that of squat exercise(p<.001), and the center of pressure movement length of kneeing squat exercise has also been found to be relatively shorter (p<.001). Moreover, kneeling squat exercises have been found to have a significantly slower center of pressure movement speed than squat exercise (p<.001), and kneeing squat exercise center of pressure movement distance from the center of the X-axis has been found to be significantly small (p<.001). Conclusion : Kneeling squat exercises have significantly decreased amounts of center of pressure movement area, distance, and speed compared to squat exercises. Also, the center of pressure movement distance from the center of the X-axis was relatively closer. This result seems to derive from patients performing their motions with wide base surfaces while being refrained from using unstable ankle joints during kneeing squat exercise. Therefore, it can be concluded that kneeing squat exercises show relatively balanced center of pressure movements between the paralyzed and non-paralyzed sides because kneeling squats show smaller shakes in the center of pressure.

• PNF and Movement
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• v.21 no.2
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• pp.255-263
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• 2023

Purpose: This study aims to investigate the immediate effects of electromyography (EMG) biofeedback training of the gluteus medius on dynamic balance during single leg squats in healthy individuals. Methods: The sample size in this study was estimated using the G-power program at an effect size of 0.4, a significance level (α) of 0.05, and a testing power of 0.90. In addition, as a result of considering the 10% dropout rate, this study recruited 21 healthy individuals (8 males and 13 females). All subjects measured the Y-balance test-lower quarter (YBT-LQ) and limits of stability (LOS) before and after a single leg squat (SLS) and SLS with EMG biofeedback training of the gluteus medius (SLSEB). They were trained for 10 minutes for each exercise, and two dynamic balance tests were performed three times. Results: There was a significant difference in the YBT-LQ score between the two exercises (p < 0.05). In the YBT-LQ score, there was a significant difference before and after SLS and SLSEB (p < 0.05). SLSEB showed a significantly higher YBT-LQ score than SLS (p < 0.05). There was a significant difference in LOM between the two exercises (p < 0.05). However, there was no significant difference between the two exercises. Conclusion: A single-leg squat with EMG biofeedback exercises is an effective method to improve dynamic balance, such as the YBT-LQ.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.69-76
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• 2023

Purpose : This study aimed to compare lung capacity measures (forced vital capacity; FVC, forced expiratory volume at 1 second; FEV1, and FEV1/FVC) and the activities of rectus femoris (RF) and gastrocnemius (GCM) muscles between young adults prescribed aerobic exercise combined with lower limb strength exercise (complex exercise) and those prescribed only aerobic exercise. Methods : We randomly divided 22 young adults into 2 groups: the complex exercise group that combined the leg strengthening and aerobic exercises (n = 11) and the aerobic-exercise-only group (n=11). Before the intervention, the FVC, FEV1, and FEV1/FVC values and the activities of RF and GCM muscles were measured. Measurements were in triplicates, and the average of the 3 measurements was used. The complex exercise group performed the treadmill exercise followed by squats and lunges, and the group performed only the treadmill exercise. Both groups were allocated the same time. Both groups performed the assigned exercise thrice a week for 3 weeks. After the intervention, the FVC, FEV1, and FEV1/FVC values and the activities of RF and GCM muscles were measured again. Results : The FVC and FEV1 values increased significantly in both groups after the intervention (p<.05). RF activity increased significantly after the intervention in the complex exercise group (p<.05), and the magnitude of change in RF activity after the intervention was significantly higher in the complex exercise group than in the aerobic-exercise-only group (p<.05). GCM activity also significantly increased after the intervention in both groups (p<.05). Conclusion : On the basis of our results, we recommend combining leg strengthening and aerobic exercise to improve leg muscle activity along with lung function.

• Journal of Fashion Business
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• v.27 no.5
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• pp.93-107
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• 2023

This study aimed to design a knee brace with dry electrode EMS (Electrical Muscle Stimulation) for elite badminton players suffering from knee pain and assess its effectiveness in relieving pain and improving mobility. The assessment measured knee joint range of motion (ROM), Sargent jump height, and pain perception using a visual analog scale (VAS). Four experimental groups were established: stability, pain induction after 100 squats, muscle soreness induction with a regular knee brace, and muscle soreness induction with the EMS knee brace. The most suitable knee brace was selected from four samples to design the EMS knee brace. The conductive fabric was integrated into the inner surface of the knee brace to enhance EMS conductivity for the quadriceps muscles. Tensile strength tests showed that the dry electrode did not significantly affect the physical functionality of the knee brace.Regarding knee joint ROM and Sargent jump height, the EMS knee brace outperformed muscle soreness induction with a regular knee brace and wearing a standard knee brace. VAS measurements demonstrated that the EMS braces effectively alleviated pain perception in most cases. The results indicate the potential for developing EMS braces to alleviate pain and prevent injuries for athletes across various sports.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.5
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• pp.330-338
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• 2024

With the growing interest in rehabilitation therapy and exercise programs, there is an increasing need for smart content that simultaneously addresses both health and engagement. Particularly, exercises performed in a state of physical imbalance carry a high risk of injury, making it essential to detect and integrate balance into the training process. This paper proposes Rehabilitation Training program that combines a pressure platform with virtual reality (VR) technology to address this issue. The program enables users to perform exercises such as squats, stationary walking, and forward-backward walking in a VR environment, utilizing real-time foot pressure data captured through a pressure mat. Additionally, an algorithm based on YOLOv8-pose extracted skeletal coordinates is proposed to assess body balance and automatically count squat repetitions. The experimental results showed an average accuracy of 87.9% for each posture, confirming that users can be provided with a safer, more efficient, and immersive training experience through this approach.

• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.509-515
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• 2020

The purpose of this study was to analyze the correlation between passive ankle movement range and knee joint kinetic variables during squat movement. In this study, a total of 27 subjects participated in this study, 19 men and 8 women, who had no history of the musculoskeletal system of the lower extremity. To verify the correlation between the ankle joint flexibility and the knee joint kinetic variables during deep squat, it was performed pearson's correlation coefficient and variables showing statistically significant correlation were performed by simple regression analysis at a significant level of α .05. Through this study, the relationship between the peak joint moment and joint reaction force factors that determine ankle joint flexibility and knee joint pressure was confirmed. Therefore, when applying an exercise that can generate a lot of load on the knee joint such as deep squats during strength training, checking the degree of flexibility of the ankle joint among physical characteristics to the individual may reduce the stability of the body and the risk of injury to the knee joint. It is expected to be helpful in setting the intensity of exercise that can be done.