• The Journal of Korean Physical Therapy
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• v.17 no.2
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• pp.38-45
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• 2005

This study was deigned to identify the effect of electromyographic activity of knee extensor during contralateral hip isometric adduction. six young adults who had not experienced any knee injuries were recruited. Their Q-angles were within a normal rage. They were asked to sit on the table. The EMG activities of the vastus lateralis (VL), vastus medialis oblique (VMO) were recorded in sitting by surface electrodes and normalized by MVC EMG values derived from manual muscle test. The EMG activity levels of the VL, RF, and VMO were the highest when foot was externally rotated. The EMG activity level of VMO/VL ratio did show significant differences(p<.05). The onset time of vastus lateralis (VL) and vastus medialis oblique (VMO) was similar in contralateral hip isometric adduction(p<.05).

• Journal of Korean Physical Therapy Science
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• v.23 no.1
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• pp.24-32
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• 2016

Purpose: Muscle imbalance around the knee region, especially quadriceps imbalance, is considered one of the main contributing factors to the development and progression of knee dysfunction based on the changes observed via electromyography (EMG). This study aimed to investigate the effect of vastus lateralis (VL) inhibition taping using non-elastic tape on the EMG activity of the vastus medialis oblique (VMO) and VL during isometric knee extension. Method: Thirty-three healthy young adults (11 males and 22 females) were recruited. With and without VL inhibition taping, the participants performed isometric knee extension in the sitting position for a total of 7 seconds. Result: VMO/VL EMG ratio significantly increased after VL inhibition taping (p<.05). Conclusion: These findings suggest that VL inhibition taping may contribute to VL inhibition and may help improve VMO/VL ratio in young adults. We expect VL inhibition taping to be useful in individuals with greater VL than VMO activity

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.4
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• pp.291-297
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• 2014

The purpose of this study was to investigate the change of the electromyographic activity in vastus medialis oblique (VMO) and vastus lateralis (VL), also vastus medialis oblique/vastus lateralis ratios after wearing wedged flated or 5cm heel shoes. The subjects were 30 healthy women who randomly assigned to two group, divided by flated or 5cm heel group. They were asked to perform squat exercise in two postures using medial and lateral wedged shoes. In two groups, EMG activity of VMO and VL was significant difference between the flated heel and 5cm heel (p<.01). This study showed that 5cm heel could selectively more active VMO than flated heel. It should be considered the heel height as the parameter when the patient with lower extremity problem undergo rehabilitation exercise or design of orthoses for the selective muscle activity of knee pain or knee instability.

• Physical Therapy Korea
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• v.8 no.2
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• pp.65-72
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• 2001

The purpose of this study was to investigate the effect of knee exercises on the onset times of vastus medialis oblique muscle (VMO) and vastus lateralis muscle (VL) and in healthy subjects. Fifteen subjects (7 men, 8 women) in a mean age of 26.4 years participated in the study. Electromyographic (EMG) signals were recorded from the VMO and VL under four exercises. Knee exercises consisted of open kinematic terminal knee extension, straight leg raising, isometric hip adduction exercise, and closed kinematic terminal knee extension. No significant differences were found in the onset times of EMG activities of VMO and VL in the four exercises. There were also no significant differences among the exercises. These results coincided with previous studies that found no difference between onset of VMO and VL. However, it is difficult to say that there is no difference between onset of VMO and VL in healthy subjects. To confirm this results, further researches that follow same on set determination metod and exercises are needed. Not only is the study of onset time of muscle needed, but also the studies of the amount of activation and the rate of increase of muscle activation are needed.

• Physical Therapy Rehabilitation Science
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• v.6 no.1
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• pp.39-44
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• 2017

Objective: The purpose of this study is to show the effectiveness of performing squat exercises at various angles to show the maximum muscle activity of the Vastus Medialis Oblique (VMO) and Biceps femoris (BF). Design: Cross-sectional study. Methods: A total of seventeen healthy young adults (8 males and 9 females) voluntarily participated in the study. All subjects randomly performed three different squat variations as follows: A squat performed with the ankle joint at $0^{\circ}$ of incline, a squat performed with the ankle joint at $5^{\circ}$ of incline, and a squat performed with the ankle joint at $10^{\circ}$ incline. Muscle activity was measured using surface electromyography. Electrodes were placed on the VMO and BF to measure the muscle activity on the various ankle angles for comparison analysis. Results: There was a significant increase in bilateral VMO muscle activation at $10^{\circ}$ of incline compared to $0^{\circ}$ and $5^{\circ}$ (p<0.05). Greater increases in muscle activation and exercise effect was observed with increasing incline angles of the board. Changes in bilateral BF muscle activity were found; however, none were found to be significant. Conclusions: Bilateral VMO activity was found to be significant when the squats were performed at an ankle angle of $10^{\circ}$ of incline when compared to at an ankle angle of $0^{\circ}$ and $5^{\circ}$ of incline. Squats performed on an incline can be recommended as an effective method to facilitate lower extremity muscle activities.

• Physical Therapy Korea
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• v.16 no.3
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• pp.42-49
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• 2009

This study examined the vastus medialis oblique (VMO) and the vastus lateralis (VL) onset time differences (OTD) during quadriceps contraction in different hip positions. Twelve healthy subjects were recruited (four men, eight women). Surface EMG activities of the VMO and VL were measured during a quadriceps strengthening exercise in a long sitting condition and in a sitting at a chair with feet hanging condition. For each condition, subjects were tested in two hip positions (neutral and adduction). The OTD between the two muscles was calculated for each condition, by subtracting the onset time of the VL from the VMO. Therefore, the negative value of OTD represent earlier EMG onset of the VMO compared to the VL. The OTD was not significantly different between the hip neutral and the hip adduction position in the long sitting condition (p=.064). However, the OTD was significantly different between the hip neutral position ($15.83{\pm}109.51$ ms) and hip adduction position ($-5.58{\pm}121.08$ ms) during the sitting at a chair with feet hanging condition (p=.047). The negative OTD value in the hip adduction condition during quadriceps strengthening exercises is the result of earlier onset of the VMO than VL. Therefore, quadriceps contraction in the hip adduction position can prevent the risk of patella lateral tracking. We expect that quadriceps strengthening exercise in the hip adduction position will be a safe way to prevent patellofemoral pain syndrome resulting from abnormal patella lateral tracking.

• PNF and Movement
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• v.21 no.1
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• pp.107-117
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• 2023

Purpose: The aim of this study is to compare the immediate effects of weight-assisting methods on vastus medialis oblique (VMO) and vastus lateralis (VL) muscle activation, on the VMO/VL muscle activation ratio, and on muscle onset time in healthy subjects when ascending stairs. Methods: Healthy participants were randomly assigned to the belt group (n = 11), hand group (n = 11), and control group (n = 11). In the belt group, a belt was wrapped around the sacrum and pulled forward with both hands, moving the center of weight forward, while ascending stairs. The hand group grasped the hips with both hands and climbed stairs, assisting their weight from the rear and moving the center of weight backward, and the control group climbed the stairs without any intervention. Results: Muscle activation of the VMO decreased significantly after the intervention in the belt and hand groups, and activation of the VL muscle in both groups showed a greater decrease than that of the VMO muscle. Further, the VMO/VL muscle activation ratio increased significantly, with an improvement shown in the order of the belt group, hand group, and control group, while muscle onset time also improved in the order of the belt group, hand group, and control group. Conclusion: The belt group demonstrated the greatest effect across all dependent variables, confirming that in clinical practice, these two weight-assisting methods are more effective interventions during stair ascent for patients with knee joint instability, pain, and imbalance than no assistance.

• Bulletin of the Korean Mathematical Society
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• v.58 no.1
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• pp.205-215
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• 2021

In [1], Beznosova proved that the bound on the norm of the dyadic paraproduct with b ∈ BMO in the weighted Lebesgue space L2(w) depends linearly on the Ad2 characteristic of the weight w and extrapolated the result to the Lp(w) case. In this paper, we provide the weighted norm estimates of the dyadic paraproduct πb with b ∈ VMO and reduce the dependence of the Ad2 characteristic to 1/2 by using the property that for b ∈ VMO its mean oscillations are vanishing in certain cases. Using this result we also reduce the quadratic bound for the commutators of the Calderón-Zygmund operator [b, T] to 3/2.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.18 no.2
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• pp.41-47
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• 2012

Background: This study was designed to investigate the correlation between electromyography (EMG) activities in the vastus medialis oblique (VMO) vs vastus lateralis (VL) activity ratio and the valgus collapse knee position while stepping down. Methods: Twenty healthy women volunteered to participate in this study. We measured the frontal-plane projections of the knee valgus angle, knee valgus distance, and hip adduction angle by using a digital camcorder. After 3 repetitions of the step down (dominant side) exercise, the findings of the static and dynamic phases were analyzed. EMG activities data of the VMO:VL activity ratio were recorded during the step down exercise and were normalized to the maximal voluntary isometric contraction (MVIC) of the quadriceps. A paired t-test was used to compare the findings of the static and dynamic phases. We analyzed the Spearman's rank order correlation coefficient between the and VMO:VL ratio. Results: Hip adduction angle, knee valgus angle, VMO activity, VL activity, VMO:VL activity ratio were statistically higher in the dynamic phase than in the static phase (p<.05). Frontal-plane projections of knee valgus angle were significantly correlated with hip adduction angle (r=.459, p<.05) and knee valgus distance (r=.505, p<.05). However, the EMG activity ratio of the VMO and the VL did not show a significant change during step down exercise with respect to hip adduction angle (p=.875), knee valgus angle (p=.618), and knee valgus distance (p=.701). Conclusion: The results from this study indicate that frontal-plane projections of knee valgus angle were associated with hip adduction angle and knee valgus distance. On the basis of these results, the knee valgus distance may be used to determine the valgus collapse knee position while stepping down.

• Journal of the Korean Mathematical Society
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• v.54 no.5
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• pp.1357-1377
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• 2017

In this article, we first give the $L^p$ boundedness of the operator $D^2L^{-1}$ with BMO coefficients and a potential V satisfying an appropriate reverse $H{\ddot{o}}lder$ condition, then obtain global $W^{1,2}_p$ estimates for the nondivergence parabolic operator L with VMO coefficients and a potential V satisfying an appropriate reverse $H{\ddot{o}}lder$ condition.