• Korean Journal of Applied Biomechanics
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• v.30 no.4
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• pp.311-319
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• 2020

Objective: The purpose of this study was to examine of this study is to study the effect of squat exercise on muscle activation in a sling device using various types of ropes and to propose an effective sling exercise method for strengthening the lower extremity strength. Method: 20 adult male subjects (age: 25.2±2.4 yrs, height: 176.5±3.2 cm, weight: 77.2±4.5 kg) participated in this study. In the experiment, a total of four squats were conducted: squat [SE], sling squat using inelastic rope [IR], sling squat using elastic rope [ER], and sling squat using two elastic ropes [TER]. Squats were performed 5 times for each condition, and a 60-second break was given for each condition to minimize muscle fatigue. The activation of biceps brachii, rectus femoris, gastrocnemius, and tibialis anterior muscles was measured. Results: It was found that the activation of all muscles was the lowest during the squat exercise [SE]. During the sling squat using inelastic rope [IR], the muscle activation of the biceps brachii was the highest. During the sling squat using elastic rope [ER], the activation of the rectus femoris, gastrocnemius, and tibialis anterior muscles was found to be the highest. In the sling squat using two elastic ropes [TER], most of the muscle activation was similar to that of the sling squat using inelastic rope [IR]. Conclusion: Our results of the experiment, it was found that sling squat exercise using elastic rope had a positive effect on the activation of all muscles. It is thought that performing a squat exercise under moderate weight load and unstable conditions, such as sling squat exercise using elastic rope, can increase the muscle activity of the lower limbs and perform more effective exercise effect than performing a conventional squat exercise under stable conditions. In the future, if research is conducted not only on adult men, but also on various ages and patients, it will be able to provide positive help in improving balance, stability and stamina through squat exercise.

• 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.

• Physical Therapy Korea
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• v.26 no.4
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• pp.20-28
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• 2019

Background: The wall squat exercise has been recommended for strengthening of the lower extremity muscles with maintaining lumbar lordosis. Although squat has been studied to be related to lower extremity extensor strength, the relationship between wall squat and lower extremity extensor strength unclear. Because squat and wall squat are biomechanically different, study on the relationship is needed. Objects: The purpose of this study was to determine the lower extremity extensor strength associated with wall squat performance. Methods: 74 healthy volunteers were recruited to participate in this study. The volunteers were measured hip and knee extensors strength and then performed wall squat exercise for maximum count. Results: We found significant relationships between wall squat performance and hip extensor strength normalized by body weight, knee extensor strength normalized by body weight and the composite value. In a regression analysis, hip extensor strength normalized by body weight explained 29% of the variation in wall squat performance in males and 35% in females. Conclusion: These results demonstrate that hip extensor strength normalized by body weight is critical to wall squat performance in both sexes.

• Physical Therapy Korea
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• v.24 no.1
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• pp.79-85
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• 2017

Background: The wall squat is considered an effective exercise because it can reduce the knee load and prevent excessive lumbar movement. However, the relationship between wall squat performance and strength of knee extensors and hip extensors remained unclear. Objects: The purpose of this study was to compare the strengths of the knee extensors and hip extensors between groups with low and high wall squat performance. Method: Nineteen males (low performance group: 9 subjects, high performance group: 10 subjects) participated in this study and performed wall squats. The subjects who were performing less than 30% of the average wall squat count were classified into the low wall squat performance group (less than or equal to 4 times) and the subjects who performed more than 30% of the average wall squat count were classified into the high wall squat performance group (greater than or equal to 8 times). Knee extensor and hip extensor strength were measured with a strength measurement system. An independent t-test was used to compare the strengths of the knee extensors and hip extensors between the groups with low and high wall squat performance. Results: The ratios of knee extensor and hip extensor strength to bodyweight were greater in the high wall squat performance group than in the low wall squat performance group (knee extensors: p<.001; hip extensors: p=.03). In the high- and low-performance groups, the ratios of knee extensor strength to bodyweight were $42.74{\pm}5.72$ and $30.76{\pm}8.54$, respectively, and the ratios of hip extensor strength to bodyweight were $31.95{\pm}10.61$ and $20.66{\pm}11.25$, respectively. Conclusion: Our findings suggest that knee extensor and hip extensor strength are needed for high wall squat performance. Thus, exercise to increase the knee and hip extensors strength can be recommended to improve squat performance.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.107-114
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• 2011

Closed kinematic chain exercises such as squatting have been widely indicated for knee rehabilitation in patients with patellofemoral disorders such as osteoarthritis and patellofemoral pain. Patellofemoral disorders are thought to be associated with abnormal patellar kinematics. In addition, the Q-angle may be undervalued in patients with patellofemoral pain and a laterally displaced patella. The purpose of this study was to assess patellar kinematics and the Q-angle during double-leg semi-squat and wall-slide semi-squat exercises. In this study, 28 asymptomatic subjects(16 male, 12 female) were assessed. Patellar tilt, patellar spin, and Q-angle were recorded using a motion analysis system during double-leg semi-squat and wall-slide semi-squat exercises. The Q-angle and patellar tilt were significantly increased, whereas patellar spin was significantly decreased, at $45^{\circ}$ of knee flexion compared with $0^{\circ}$. No differences were observed for the Q-angle, patellar tilt, and patellar spin during double-leg semi-squat and wall-slide semi-squat exercises. However, a significant interaction was observed between squat type and knee angle for patellar spin. We found that the patella is laterally tilted during semi-squat exercises and that there was no difference in patellar tracking between knee flexion during double-leg semi-squat and wall-slide semi-squat exercises.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.299-309
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• 2021

Purpose : The purpose of this study was to compare the ankle pronation squat with the general squat and investigate the effect on the geun varum and the muscles around the knee. Methods : Subjects were chosen as the target for squat exercise with the distance between the knees more than 5 cm. The selected 30 students were randomly divided into 15 pronation squat group and 15 general squat group, and performed five sets movements 20 times. Global postural system (GPS) and digital goniometer were used to check the distance between the knees and the Q angle, and muscle activity was measured with EMG during squat exercise. Results: The result is as follows. First, as a result of analyzing the change in the distance between the knees, the distance between the knees decreased and the Q angle increased in the pronation squat group after exercise. Second, as a result of analyzing the change in muscle activity of the peroneus longus, the muscle activity increased in the pronation squat group after exercise, and it was more effective than the general squat group. Third, as a result of analyzing the change in the VMO (vastus medialis oblique) and VL (vastus lateralis) muscle activity ratio, the activity ratio of the pronation squat group increased after exercise, and the imbalance in the VMO/VL muscle activity was decreased. Conclusion: The pronation squat exercise applied to the ankle will greatly affect what is made into a balanced leg as decreased of the distance between knees, increased of Q angle, increased of the muscle activity of the peroneus longus and the ratio of VMO/VL.

• 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.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.152-160
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• 2021

The purpose of this study was to investigate the difference in the number of repetitions and the change in electromyographic response during the maximum speed squat exercise according to the depth conditions and the maximum speed squat exercise according to the time of each depth. Ten men in their 20s were selected as subjects and the maximum speed squat was performed for one minute in three environmental conditions (ground, knee depth, waist depth). We found that the number of repetitions according to the depth of water showed a significant difference, and as a result of the post-mortem comparison, the number of repetitions was higher in the ground condition and the knee depth than in the waist depth. And the muscle activity of rectus abdominis, erector spinae, rectus femoris, biceps femoris was increased during ground squat exercise, activity of all muscle was decreased during knee depth squat exercise, and activity of rectus abdominis, erector spinae, biceps femoris, tibialis anterior, gastrocnemius was decreased during waist depth squat. In conclusion, muscle activity of lower extremities during squat exercise in underwater environment can be lowered as the depth of water is deep due to buoyancy, but muscle activity of trunk muscles can be increased rather due to the effect of viscosity and drag.

• The Journal of Korean Physical Therapy
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• v.22 no.5
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• pp.57-61
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• 2010

Purpose: The purpose of this study was to identify the effect of active foot arch support on the muscles of lower extremity electromyographic activity during squat exercise in persons with pronated foot. Methods: The study subjects were 16 persons with pronated foot. They have no history of surgery in lower extremity and trunk and limitation of range of motion or pain when performing squat exercise. Each subject was measured the navicular drop (ND) to determine the pronated foot. And then the subjects were asked to perform three repetitions of a $90^{\circ}$ knee flexion squat in both conditions which are 1) preferred squat and 2) squat with active foot arch support. Results: Paired t-test revealed that squat with active foot arch support produced significantly greater EMG activities in abductor hallucis (p=0.00), proneus longus (p=0.03) and gluteus medius (p=0.04) than preferred squat. But the EMG activities of tibialis anterior, vastus medialis oblique and vastus lateralis were not showed significantly different between the both squat conditions. Conclusion: The findings of this study suggest that active foot arch support during squat increase the activities of lower extremity muscles which are the abductor hallucis, proneus longus and gluteus medius. Also, the abductor hallucis which is one of the planter intrinsic muscle and peroneus longus play a role in support of the foot arch and active foot arch support induced the increase of the activity of gluteus medius. Therefore active foot arch support can change the lower extremity biomechanics as well as passive foot support such as foot orthotics and taping.

• Journal of Korean Physical Therapy Science
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• v.25 no.1
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• pp.20-30
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• 2018

Background: This study evaluates the effects of lower muscle activity of squat exercise on supporting surface and visual feedback. Methods: The subjects include 30 healthy subjects. To measure muscle activation of the lower limb during squat exercise(stable and unstable surface, visual and unvisual). For evaluation of muscle activation(rectus femoris, biceps femoris), was measured using the Electromyogram, EMG was used. Results: The results shows that Rectus Femoris(RF) and Biceps Femoris(BF) muscle activations were significantly (p<0.05) difference in unvisual-unstable surface(USUV), unvisual-stable surface(SUV), visual-unstable surface(USA), and visual-stable surface(SV) during squat exercise. Conclusion: Squat exercise can improve muscle activation of the lowe limb. particularly, unvisual-unstable surface during squat exercise can improve muscle activation of the lowe limb.