• Journal of the military operations research society of Korea
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• v.8 no.1
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• pp.77-98
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• 1982

Experiments have been performed for estimating the individual muscle capabilities of the biceps brachii and the quadriceps femoris muscle. The surface EMG has been recorded on the bellies of the biceps brachii and the quadriceps femoris muscle during isometric contractions at $50\%,\;75\%,\;and\;100\%$ MVC. The rectified EMG amplitudes of the maximum voluntary contraction (MVC) were in the range of $2.8\~3.0\;mV\;and\;6.9\~7.2\;mV$ the biceps brachii and the quadriceps femoris, respectively. In the biceps brachii, Type S motor units were recruited in the range of $41\~49\%$ MVC; and Type F motor units were recruited in the range of $51\~59\%$ MVC, In the quadriceps femoris, Type S, Type SF, and Type F motor units were recruited in the ranges of $31\~38\%,\;33\~48\%$, and $21\~29\%$ MVC respectively.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.4
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• pp.541-550
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• 2012

PURPOSE: The purpose of this study was compare quadriceps femoris muscle activity while performing wall slide squats of four methods. METHODS: Forty subjects, with no history of patellofemoral pain, quadriceps injury, or other knee injury volunteered for this study. Muscle activation of the vastus medialis obliquus, rectus femoris, vastus lateralis muscles were recorded while subjects performed 10 consecutive wall slide squats. Subjects performed the wall slide squats during four different methods: (1) basic wall slide squat, (2) keep back upright against fitness ball, (3) standing of unstable surface, (4) squeezing ball between both knees. Statistical analysis were accomplished by utilizing the one-way ANOVA(Bonferroni's post-hoc test) by SPSS 20.0 program. Significance level was set at p<.05. RESULTS: Muscle activations induced wall slide squats of four methods compared and results showed that there was significant difference only in vastus medialis obliquus and rectus femoris but there was no significant difference in vastus lateralis. The vastus medialis obliquus was significantly different only keep back upright against fitness ball at post-hoc test. The rectus femoris was significantly different keep back upright against fitness ball and standing of unstable surface at post-hoc test. CONCLUSION: Based on these results, we conclude that quadriceps femoris muscle activations are differenced by performing wall slide squats of four different methods in healthy subjects. These data suggest that for quadriceps muscle strengthening, exercise professionals can perform the wall slide squats by altering several task variables. Further research is needed to determine the exact mechanism by which quadriceps function is altered.

• PNF and Movement
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• v.16 no.1
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• pp.125-132
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• 2018

Purpose: The aim of this study was to investigate the isolated activation ratio of the quadriceps femoris muscle on different support surfaces during squat exercise. Methods: Twenty participants (10 males and 10 females) voluntarily agreed to participate in the research after receiving an explanation about the purpose and process of the study. Each participant performed squat exercises on three different support surfaces (a flat surface, a form roller, and an unstable surface). Muscle activities of the rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) were measured by electromyography. The isolated activation ratio of the quadriceps femoris muscle was calculated using the %isolation formula. Results: For the squat exercise, the %isolation value of the VM was significantly higher on the unstable surface than on the flat surface and form roller. In contrast, the %isolation values for the RF for the squat exercise were significantly higher on the flat surface and form roller than on the unstable surface. There was no significant differences in the %isolation values of the VL on the three different surfaces. Conclusion: The findings indicate that squat exercise on different surfaces results in differential activation of the quadriceps femoris muscle, which suggests that squat exercise on a multi-directional unstable surface could increase the isolated activation ratio of the VM.

• Journal of Korean Physical Therapy Science
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• v.15 no.3
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• pp.65-72
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• 2008

Background : The purpose of present study was to investigate the effect of quadriceps femoris taping in normal gait using 3D motion capture technique. Method : Twenty healthy volunteers, have no musculoskeletal problems, were recruited as subjects for this study. In experimental group, 20 healthy young(males 10 and females 10) were included. The subjects were assessed during two conditions: control tape(no muscle stretched) and quadriceps (muscle stretched)taping application. To obtain the dynamic data, we captured the motion of subject attached markers without taping during repeated gaits five times or more in 7 m Capture volume of gait analysis center. The result was obtained as a mean value in three times. After taping on quadriceps femoris, the same procedure was carried out. Statistical analysis were performed using statistical software packagess SPSS WIN 12.0(SPSS, Chicago, IL, USA). Differences were tested for statistical significance using paired t-test, independent t-test, chi-squared test for comparisons between the muscle stretched and no muscle stretched. Results : The date of 20 subjects who carried out the whole experimental course were statistically analyzed. 1. gait velocity was showed that muscle stretched group had more significantly increased than no muscle stretched group(p<.05). 2. step length was showed that muscle stretched group had more significantly increased than no muscle stretched group(p<.05). 3. cadens was showed that muscle stretched group had more significantly increased than no muscle stretched group(p<.05). Conclusion : kinesio taping on quadriceps femoris promoted cadence, gait velocity, step length in normal subject (muscle stretched) group.

• Physical Therapy Rehabilitation Science
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• v.10 no.3
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• pp.367-373
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• 2021

Objective: Short foot exercise(SFE) is frequently used to increase the medial longitudinal arch of the foot, as well as the intrinsic foot muscles. This studyinvestigated the effects of SFE onmuscular activity and the onset of contraction of the quadriceps femoris muscle during squats in healthypeople. It also aimed to compare and analyze the results with those of the general squat method and propose a more efficient squat method. Design: Cross-sectional study. Methods: This study compared 20 adults (male=10, female=10) who statisfied the inclusion criteria for the muscle activity and onset of the muscle contraction of the quadriceps femoris using surface EMG under two conditions: general squats and SFE squats. Results: Separate analyses and comparisons of the outcomes of the SFE squat and the general squat, showed a significant increase in the muscle activities of the rectus femoris and vastus medial muscles in both males and females (p<0.05). The onset of muscle contraction was significantly delayed for the vastus lateralis relative to that for the vastus medialis (p<0.05). However, it delayed significantly in females, but not in males. Conclusions: The SFE squats induced selective muscular activities of the rectus femoris and vastus medialis muscels and affected the onset of contraction of the vastus medialis and lateralis muscles.

• Journal of Korean Physical Therapy Science
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• v.9 no.3
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• pp.67-75
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• 2002

The purpose of this study was to evaluate the effects of quadriceps femoris flexibility exercise which would improve the degree of knee flexion range of motion, extension torque, and the activities of daily living (ADL) in elderly subjects with degenerative knee arthritis. Fourteen elderly patients (two men and twelve women) with degenerative knee arthritis participated and had a quadriceps femoris flexibility exercise intervention program in this study. The mean age of the patients was 70.00 years for men and 71.16 years for women. This study carried out the experimental study of one group pretest-posttest design, which evaluated the degree of knee flexion range of motion, extension torque, the ADL ability of the patients before and after applying the exercise intervention for five weeks. The results of this study are as follow: 1. The knee flexion ranges of motion of the patients were measured before and after the intervention and the ranges increased significantly both in the left and right knee flexion range of motion (p < 0.05). 2. The peak torque of the knee muscle, the peak torque/body weight, and average power of the patients showed significant increases in both in the left and right knee after applying the intervention (p < 0.05). 3. The intervention produced a significant reduction in pain of the patients (p < 0.05). Their functional activities of ADL improved significantly compared with before the intervention (p < 0.05). It has been shown that the quadriceps femoris flexibility exercise intervention program increased significantly the knee flexion range of motion, and extension torque, as well as an increase in performance of functional activities of ADL of the patients. Thus, the quadriceps femoris flexibility exercise should be considered as one of the therapeutic exercises for the elderly patients with degenerative knee arthritis applied.

• Physical Therapy Korea
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• v.8 no.2
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• pp.1-16
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• 2001

This study was designed to identify the effects of foot position on electromyographic (EMG) activity of the quadriceps femoris during maximum voluntary contraction (MVC) in standing. Twenty young adults who had not experienced any knee injuries were recruited. Their Q-angles were within a normal range. They were asked to stand in five different foot positions ($40^{\circ}$ externally rotated, $30^{\circ}$ internally rotated, neutral, $20^{\circ}$ plantarflexed, and $10^{\circ}$ dorsiflexed foot position). The EMG activities of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis oblique (VMO) were recorded in standing by surface electrodes and normalized by MVC EMG values derived from manual muscle test. The normalized EMG activity levels (%MVC EMG) of muscles in the five foot positions were compared using repeated measures ANOVA. The EMG activity levels of the VL, RF, and VMO were the highest when foot was externally rotated. The EMG activity levels of the VL and RF were significantly different among the foot positions (p<.05). However, EMG activity levels of the VL, RF, VMO, and VMO/VL ratio did not show significant differences in each foot position (p> .05). The results suggest that the quadriceps femoris may be effectively activated by performing MVC at an externally rotated foot position. Therefore, the externally rotated foot position can be considered as an effective foot position for quadriceps femoris strengthening exercise. Further studies are needed to identify whether there are differences in the effects of foot position on muscle strength after MVC exercise of quadriceps femoris in standing.

• The Journal of Korean Physical Therapy
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• v.35 no.2
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• pp.53-57
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• 2023

Purpose: The purpose of this study was to compare the changes in the muscle activation of the quadriceps muscle (rectus femoris, vastus lateralis, vastus medialis) during the stand-to-sit (StandTS) movement according to the plantar flexion angle of the ankle joint. Methods: A total of 22 healthy young females participated in this study. During the StandTS under the three conditions (plantarflexion angle 0°, 20°, and 45° of the ankle), electromyography (EMG) data (% maximum voluntary iso¬metric contraction) of the rectus femoris, vastus lateralis, and vastus medialis were recorded using a wireless surface EMG system. Results: There was a significant difference in the muscle activation of rectus femoris, vastus lateralis, and vastus medialis according to the plantar flexion angle (0°, 20°, and 45°) of the ankle. The muscle activation of the quadriceps was the highest at a 45° angle of plantarflexion and the lowest at 0°. One-way repeated ANOVA was used to analyze the muscle activation data of the lower extremity muscles according to the angle of the ankle joint. Conclusion: Based on the results of our study, it was confirmed that the muscle activity of the quadriceps can be increased even in the StandTS movement, which involves the eccentric contraction of the quadriceps muscle. This suggests that maintaining a plantar flexion posture for a long time, say by wearing high-heeled shoes, can quickly cause muscle fatigue in the lower-limb muscles, which can cause a decrease in balance ability leading to falls.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.9-17
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• 2018

PURPOSE: This study was conducted to compare the effects of the Graston-based massage method and microcurrent application on muscle fatigue after causing muscle fatigue of the quadriceps femoris by applying high-intensity exercise. METHODS: Study subjects (56 healthy subjects in their 20s) were randomized into a microcurrent group (MG), Graston group (GG), and control group (CG). To induce fatigue of the quadriceps femoris, the subjects performed squats 100 times without a break within about 5 minutes. Muscle fatigue was measured immediately after performing squats and 15 minutes after intervention. To measure muscle fatigue, surface electromyogram (EMG) was used to obtain and compare the median frequency. Microcurrent or Graston massage was applied to their quadriceps muscles 15 minutes after performing the squats. RESULTS: Muscle fatigue increased significantly in the vastus lateralis before and after intervention in the Graston group (p<.05), while no significant difference was observed in the rectus femoris and vastus medialis (p>.05). There were also no significant differences in the microcurrent group or the control group. CONCLUSION: Both the microcurrent group and Graston group showed a tendency for increasing median frequency values compared to the control group, but there was no significant difference except in the vastus lateralis treated with the Graston technique. Although there was no significant difference, the Graston technique could be utilized to reduce the occurrence of DOMS by preventing muscle fatigue in clinical practice or sports medicine.

• Journal of the Korean Society of Physical Medicine
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• v.3 no.2
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• pp.75-80
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• 2008

Purpose : The purpose of this study was to evaluate the effects of local vibration on quadriceps femoris on vertical jump Method : The subjects(40) were divided into man control group(10) woman control group(10) and man vibration group(10), woman vibration group(10). Vibration group was given vibration on quadriceps femoris for 15 minutes and control group was given resting for 15 minutes. All subjects of each group were tested on vertical jump then pre and post test. Results : 1. Man control group and woman control group vertical jump didn't have statistically difference pre and post test(p>0.05). 2. In the woman vibration group vertical jump didn't have significant difference pre and post test(p>0.05), but had significant difference in the man vibration group(p<0.05) Conclusion : Vibration on quadriceps femoris have an effect on vertical jump. Therefore, the vibration will be effective in treatment of muscle strength.