• Physical Therapy Korea
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• v.19 no.3
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• pp.105-114
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• 2012

This study was performed to compare the muscle activity of lumbar stabilizers between stoop and semi-squat lifting techniques at different lifting loads. Twenty healthy subjects (9 males, 11 females) were recruited for this study. Muscle activity of external obliques (EO), internal obliques (IO) and lumbar multifidus (LM) muscle was measured by surface electromyography during stoop and semi-squat lifting at different lifting loads (10%, 20%, and 30% of the subject's body weight). A one-way repeated measure ANOVA was applied. The results showed that EMG activity of EO was significantly increased with a load of 30% of body weight compared to 10% and 20% of body weight in both lifting techniques (p<.05). Muscle activity of LM was significantly increased in 20% compared to 10% and 30% compared to 10% of subject's body weight in stoop lifting and the muscle activity of LM was significantly increased in 20% compared to 10%, 30% compared to 20%, and 30% compared to 10% of the subject's body weight in semi-squat lifting (p<.05). However, there was no significant difference in activity of IO according to lifting loads in both lifting techniques. There were no significant differences in muscle activity of EO, IO, and LM between stoop and semi-squat technique (p>.05). Therefore, the results of this study suggested that the EO can contribute to increase the lumbar stability during stoop and semi-squat lifting at 30% of body weight rather than at lower loads, and the LM seems to act as counteractor to imposed loads during stoop and semi-squat lifting with increasing loads.

• The Journal of Korean Physical Therapy
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• v.24 no.2
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• pp.134-142
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• 2012

Purpose: This study examined the effect on postural control during the stimulation of haptic touch with fingertip on the stable surface at quiet standing posture, squat flexion stage, 60 degrees squat stage and squat extension stage. Methods: The postural sway was measured on the force platform, while 30 subjects were squatting, under three different haptic touch conditions (No Touch [NT], Light Touch [LT], Heavy Touch [HT]), above the touch pad in front of their body midline. Three different haptic touch conditions were divided into 1) NT condition; squatting as right index fingers held above the touch pad, 2) LT condition (<1N); squatting as the touch pad was in contact with right index fingers pulp with a pressure not exceeding 1N and 3) HT condition; squatting as subjects were allowed to use the touch pad for mechanical support by transmitting onto it with as much force, choosing with their index fingers. Results: There was significant decrease in LT, rather than that of NT (p<0.01), and in HT, rather than that of LT (p<0.01), as the results of the distance and velocity of center of pressure (COP) in mediolateral direction at quiet standing position. In anteroposterior direction, the distance and velocity of COP in LT and HT showed significant decrease, when compared to that of the data of NT (p<0.01). There was no significant difference between the 3 conditions (NT, LT, and HT), with respect to the distance and velocity of COP in mediolateral direction, during dynamic balance (squat flexion stage, squat extension stage) (p>0.05). In anteroposterior direction, the results of the distance and velocity of COP in HT showed significant decrease when compared to that of the data of NT (p<0.05). Conclusion: Light touch, during the task, decreased the postural sway at static balance. The results suggest that haptic touch should be applied, appropriately, because it varies the effects according to different conditions.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.216-221
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• 2019

Purpose: This study examined the effect of visual feedback squat on the core muscle thickness of young adults experiencing back pain. Methods: Thirty adult men and women who experienced back pain were assigned randomly to 15 members of the visual feedback squat group (VSG) and 15 of the normal squat group (NSG) to train three times a week for a total of eight weeks. The core muscle thickness was compared prior to the test for four weeks and eight weeks after the test by dividing it into warm-up exercise, main exercise, and 10 minutes finishing exercise. Before, and four weeks and eight weeks later, the thickness of the core muscle was compared using an ultrasonic imaging system. Repeated measured ANOVA was performed to compare the groups, and a Bonferroni test was performed as a post-hoc test to assess the significance of the timing of the measurements in each group according to the periods. An independent t-test was conducted to test the significance between the groups according to the measurement points. Results: A significant change in the main effects of time and interactions of the time difference in muscle thickness of transvers abdominis were observed between the visual feedback squat and control groups according to the measurement point (p<0.05). No significant difference in the muscle thickness of both muscles was observed between the groups with the exception of the right abdominis (p>0.05). Conclusion: These findings suggest that visual feedback squat exercise is expected to have positive effects on the development of transverse abdominis in core muscles.

• Physical Therapy Rehabilitation Science
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• v.8 no.2
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• pp.61-66
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• 2019

Objective: The purpose of this study was to investigate the effects of resistance applied in various directions on lower extremity muscle activity and balance during squat exercise performance. Design: Cross-sectional study. Methods: Forty-one adults (19 males and 22 females) agreed to the study purpose and procedures. All subjects randomly performed squat exercises with an intensity of overcoming 10% of body weight resistance pulled forward, backward and general squats with $60^{\circ}$ of knee joint flexion. Electromyography was used to measure muscle activity of the vastus medialis oblique (VMO), rectus femoris (RF), vastus lateralis oblique (VLO), biceps femoris (BF), and semitendinosus (ST) muscles. The Wii Balance Board was used to assess balance during the three-method squat operation. Each operation was measured three times for 10 seconds. Results: There were significant differences in muscle activities of the VMO, RF, VLO, ST and balance ability with the application of three directions of resistance (p<0.05). Post hoc comparisons revealed that squats performed with resistance pulled in the backward direction resulted in higher VMO, RF and VLO activity than with the resistance placed in a pulled forward direction (p<0.05). In the ST, resistance applied in the pulled forward direction showed greater muscle activity compared to the pulled backward direction (p<0.05). With balance, squats performed with resistance pulled in the forward direction showed greater muscle activity than with resistance applied in the pulled backward direction and during general squat performance (p<0.05). Conclusions: In this study, squat exercises performed with resistance applied in the direction of pulling backwards was found to be the most effective in improving quadriceps muscle strength and balance. It is effective to provide resistance that is placed in the forward when it is difficult to perform a general squat due to weakness of the quadriceps.

• PNF and Movement
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• v.12 no.3
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• pp.167-171
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• 2014

Purpose: The purpose of this study was to show the effects of voluntary change of weight bearing on the vastus medialis oblique and the vastus lateralis ratio during squat exercise. Methods: Twenty-four healthy adults were recruited for this study. The subjects performed squat exercise with median weight bearing, lateral weight bearing and non-changed weight bearing. The muscle activities of the vastus medialis oblique and the vastus lateralis were measured during the squat for all three conditions. The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition. The statistical analyses were performed using SPSS ver. 17.0, and a p-value of less than 0.05 was considered significant for all cases. A post-hoc test was performed using Tukey's test. Results: The study showed that the vastus medialis oblique and the vastus lateralis ratio significantly changed according to the voluntary change of weight bearing during a squat. The vastus medialis oblique and the vastus lateralis ratio significantly decreased under the condition of voluntary lateral weight bearing. Conclusion: We suggest squat exercise on median weight bearing to increase the vastus medialis oblique and the vastus lateralis ratio. If your patient has.

• Journal of Korean Physical Therapy Science
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• v.29 no.1
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• pp.64-72
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• 2022

Background: The purpose of this study is to investigate the effect of wall squat exercise according to the difference in the support surface on the thickness change of external oblique, internal oblique and transverse abdominalis of the trunk muscles and the change in distance of center of pressure when the eyes are opened and closed. Design: Randomized controlled trial. Methods: The subjects were 26 healthy adults, 18 males and 8 females. The composition of each group using the single-blind method was 13 people in the unstable side wall squat exercise group and 13 people in the stable side wall squat exercise group. Experimental measurements were divided into before, 3 weeks, and 6 weeks after the experiment, and changes in muscle thickness and balance were confirmed. Muscle thickness was measured using ultrasinic, and static balance change was measured using Bio-rescue. Results: There were significant differences in the thickness changes of external oblique, internal oblique and transverse abdominalis according to the wall squat exercise method by period and in the interaction between the period and the group (p<0.05). As a result of the post-hoc analysis, there was a significant difference in the change between the two groups in external oblique muscle after 6 weeks. And there was a significant difference in the distance of the pressure center between eyes open and closed eyes (p<0.05). Conclusion: In terms of instability, wall squat exercise was positive for changes in trunk muscle thickness. It suggests the possibility of using it for trunk muscle strengthening training in the future.

• The Journal of Korean Physical Therapy
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• v.34 no.2
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• pp.63-67
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• 2022

Purpose: The purpose of this study was to investigate the effect of assistance tools such as gym balls, wedges, and straps on lower extremity muscle activity and the increase in the range of motion made possible by the use of these tools. The subjects were divided into two groups: a group capable of deep-squatting (PS) and the second finding it impossible or having difficulty in performing such squats (IS). Methods: Twenty-three subjects participated in this study. Surface electromyography was used to measure the muscle activation of the rectus femoris (RF), vastus medialis (VM), and tibialis anterior (TA) muscles during deep squats, normal squats (NS), gym ball squats (GS), wedge squats (WS), and strap squats (SS). A motion analysis system was used to measure the range of motion of the knee joint during each of these exercises. Results: There was a significant difference in the RF muscle activity between the possible squat (PS) and the impossible squat (IS) groups in the GS, and there were significant differences in the RF and TA muscle activity between the groups in the WS. Both the PS group and the IS group showed a significant difference in the TA muscle activity depending on the tool used. There were also significant differences in the range of motion of the knee joints between the intervention methods using NS and those using the tools. Conclusion: In both groups, the muscle activity of the TA muscles was lower when GS, WS, and SS were performed compared to NS. In addition, compared to NS, the range of motion of the knee joint increased when the three tools were used. This study shows that the activity of the RF, VM, and TA muscles decreased and the range of motion of the knee joint increased during deep squats for both the PS and IS groups when tools were used.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.3
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• pp.91-98
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• 2023

Purpose : The purpose of this study was to investigate the effect of the posture holding band on muscle activity of the rectus femoris, medial vastus, and vastus lateralis muscles and weight distribution during squat exercise. Methods : This study was conducted with 30 healthy adult men and women in their 20s, and all subjects were randomly assigned to the experimental group and the control group. Squat exercise was performed for 6 weeks. The experimental group received squat exercise while wearing a posture holding band, and the control group applied without wearing a posture holding band. Muscle activity of the quadriceps femoris (rectus femoris, vastus medialis, and vastus lateralis) and weight distribution (knee flexion 0 °, 30 °, 60 °, and 90 °) was measured. Results : According to the results of this study, all three muscles showed a main effect on time and group, and a significant interaction was shown only in the vastus lateralis. In addition, the value of the weight distribution difference according to the knee flexion angle did not show a main effect according to time and group at 30 ° of knee flexion, but showed an interaction. Conclusion : It was confirmed that the application of the posture holding band during squat exercise increased the muscle activity of the quadriceps muscle, and showed greater changes in the vastus lateralis muscle. In addition, it was confirmed that the difference in weight distribution was reduced in the knee flexion, and in particular, a greater change was shown in reducing the difference in weight distribution in the knee flexion of 30 °. Therefore, it is considered that the effect of the exercise can be further enhanced if the unnecessary movement of the trunk is controlled by using equipment such as a posture holding band during squat exercise.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3802-3807
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• 2010

In most sports, a key evaluator of athletic performance is sprinting speed. There are two trainable factors associated with speed including mechanical efficiency and force production. The squat exercise is one of the beneficial exercises implemented to enhance lower extremity power for sprinters. However, there has been little research on the optimal exercise intensity for sprinting performance. This study was to investigate whether performing different squat exercises prior to a 40m sprint would improve running speed. Ten male high school sprinters performed six 40m sprints following the different squat intensities (30%, 50%, 70%, and 90% of 1RM). A one-way ANOVA with repeated measures revealed that 40m sprint times had significantly improved after 50% ($5.27{\pm}0.13$, p<0.0001) and 70% ($5.26{\pm}0.15$, p<0.0001) of 1RM squat exercises compared to sprint times not following a squat % ($5.33{\pm}0.16$). Performing squat exercises with intensities of 50% and 70% of 1RM may improve 40m sprint times. Therefore, it is suggested that coaches and sprinters could include a medium intensity squat exercise (70%) in the warm-up procedure in order to improve sprint performance.

• Journal of Korean Physical Therapy Science
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• v.28 no.2
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• pp.57-64
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• 2021

Background: During squat exercises, Ankle joint stability during squat movement transfers forces produced by unstable supports or various loads to the leg joints and trunk, reducing the risk of injury; therefore, a reference is needed for correct ankle joint posture during squat exercises. The purpose of this study was to examine the effect of ankle joint stability on quadriceps femoris and hamstring activation during squat exercises. Design: Quasi-experiment one group pretest-posttest design. Methods: The participants in this study were 20 volunteers who performed squat exercises with and without kinesiology tape. We measured quadriceps femoris and hamstring activation using surface electromyography. The ankle joint was stabilized with kinesiology tape using the ankle balance taping (ABT) method. A paired t-test was performed to compare differences between taping conditions. Results: Vastus medialis and vastus lateralis activation were greater following squat exercises with kinesiology tape than without; however, the difference was not significant. Medial and lateral hamstring activation was not significantly different between taping conditions. Conclusion: Although it is difficult to maintain stability using kinesiology tape alone, ankle joint stability is believed to affect quadriceps femoris muscle activity, which increases the effectiveness of the squat exercise.