• Korean Journal of Applied Biomechanics
• /
• v.13 no.2
• /
• pp.115-122
• /
• 2003

The purposes of this study were to analyze the muscle activities and the characteristics of muscle recruting patterns of lower limb for crouching start technique using four elite splint. The EMG technique was used to record muscle activities of both right and left sides of retus femoris, vastus medialis, biceps femoris, and gastrocnemius. Eight surface electrodes were placed on the surface of the selected muscles and one ground electrode was also attached on the back of neck(C7). One video camera was also used to record the crouching start motion to define 6 events and 5 phases for further analysis. The raw EMG data were filtered with band pass filter(10-350) to remove artifacts and then low pass filtered(4Hz) to find the linear envelope which resemble muscle tension curve. This filter EMG data were normalized to MVIC for the purpose of comparison between right and left sides muscle. The results of this study were as follows. All four subjects showed that vastus medialis muscle activity was comparatively higher than those of retus femoris, biceps femoris, gastrocnemius. And left side of muscle activity was comparatively higher than right side of muscle activity. Therefore, when the subjects starting out crouching start position, we recognized that the muscle of lower limb showed interaction effect by each muscle.

• Biomedical Engineering Letters
• /
• v.8 no.4
• /
• pp.345-353
• /
• 2018

This study suggested a new EMG-signal-based evaluation method for knee rehabilitation that provides not only fragmentary information like muscle power but also in-depth information like muscle fatigue in the field of rehabilitation which it has not been applied to. In our experiment, nine healthy subjects performed straight leg raise exercises which are widely performed for knee rehabilitation. During the exercises, we recorded the joint angle of the leg and EMG signals from four prime movers of the leg: rectus femoris (RFM), vastus lateralis, vastus medialis, and biceps femoris (BFLH). We extracted two parameters to estimate muscle fatigue from the EMG signals, the zero-crossing rate (ZCR) and amplitude of muscle tension (AMT) that can quantitatively assess muscle fatigue from EMG signals. We found a decrease in the ZCR for the RFM and the BFLH in the muscle fatigue condition for most of the subjects. Also, we found increases in the AMT for the RFM and the BFLH. Based on the results, we quantitatively confirmed that in the state of muscle fatigue, the ZCR shows a decreasing trend whereas the AMT shows an increasing trend. Our results show that both the ZCR and AMT are useful parameters for characterizing the EMG signals in the muscle fatigue condition. In addition, our proposed methods are expected to be useful for developing a navigation system for knee rehabilitation exercises by evaluating the two parameters in two-dimensional parameter space.

• The Journal of Korean Physical Therapy
• /
• v.33 no.1
• /
• pp.40-46
• /
• 2021

Purpose: This study compared the muscle activity of the lower limb according to the three types of fixed angles of the ankle joint during a lunge exercise. Methods: Twenty healthy subjects performed the lunge motion in a trial including the three types of fixed angle. The lunge motion with a neutral, 20° dorsiflexion, and 20° plantarflexion of the ankle joint were randomized and measured repeatedly. The muscle activity of the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and semitendinosus (ST) was measured by surface electromyography. Results: In the change in ankle joint angle, the RF, VL, BF, and ST muscle activity showed significant differences (p<0.05). In the 20° dorsiflexion position, the muscle activity of VL, BF, and ST showed a significant decrease compared to that in the neutral position (p<0.017). The muscle activity of RF and VL in the neutral position was greater than that in the 20° plantarflexion position (p<0.017). Only the muscle activity of the BF in the 20° plantarflexion position was significantly greater than the 20° dorsiflexion position (p<0.017). Conclusion: These results revealed a difference in the muscle activity of lower extremities in the proximal region according to the angle of the ankle joint during the lunge.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.3
• /
• pp.1028-1040
• /
• 2019

The current study was performed to investigate the magnitude of exercise-induced muscle damage (EIMD) after downhill running (DR) of different intensities and to examine the availability of muscle echo intensity as biomarkers to detect regional damage within quadriceps muscle group (QG) following DR. Healthy college-age men (n=11) were experienced twice DR sessions [$50%HR_{max}$ DR, LDR; $70%HR_{max}$ DR, HDR] separated by a 2-week wash-out period with the random order. After DR, severity of EIMD according to exercise intensity were determined by serum creatine kinase (CK) activity, muscle tenderness, and neuromuscular function indicators such as a maximal voluntary isometric contraction (MVIC) and range of motion (ROM). Transvaginal B-mode imaging had been employed to evaluate regional muscle echo intensity within QG [rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; vastus intermedius, VI]. After both DR sessions, changes in serum CK activity and muscle tenderness have tended to more increase in HDR compared to those of LDR. There was a significant interaction effect between exercise intensity during DR and the time course of serum CK activity(p<.05). However, there were no statistical differences between sessions in muscle tenderness. The time course of changes in the neuromuscular functions after DR were similar to those of regional muscle echo intensity regardless exercise intensity. Although neuromuscular function showed to decline in HDR more than those of LDR after DR, no statistical differences between sessions. In contrast, there were significant interaction effects between sessions and time course of changes in RF and VL muscle echo intensity(p<.01), but not shown in those of VI and VM. These results indicated that each muscles within the QG show different response profiles for EIMD during DR, exercise intensity influences on these responses as well. In particular, current findings suggested that muscle echo intensity derived from ultrasound imaging is capable of detecting regional muscle damage in QG following DR.

• Journal of The Korean Society of Integrative Medicine
• /
• v.2 no.4
• /
• pp.49-58
• /
• 2014

Purpose : The purpose of this study was to research the effects on resistance CKC & OCK exercise method on lower limb muscle activity, in chronic stroke patients. Method : In this study, 18 patients with stroke caused by hemorrhage or infarction were participated. resistance exercise method was conducted in tow different group : one is a close kinetic chain exercise(CKC) group and the other is an open kinetic chain exercise(OKC) group. CKC with physical therapy was applied to 9 patients, and OKC with physical therapy was applied to 9 patients. Under the researcher's guidance, exercise for CKC and OKC group carried out 3 times a week for 30 minutes during 4weeks. Result : There was significantly different for the vastus lateralis, tibialis anterior and gastrocnemius muscle activity within the intervention period both group. The vastus lateralis, tibialis anterior and gastrocnemius muscle activity was significantly increased within the CKC group. The vastus leteralis and tibialis anterior muscle activity was significantly increased within the OKC group. Conclusion : It was confirmed in this study that the CKC exercise was more effective than OKC exercise in improving lower limb muscle activity of chronic stroke patients. This study seggested that CKC may be suitable for individuals with a chronic stroke. furthermore study should be made a lot of researches regarding in other method and varying conditions for many hemiplegic patients.

• The Journal of Korean Physical Therapy
• /
• v.21 no.3
• /
• pp.17-24
• /
• 2009

Purpose: The purpose of this study was to investigate the effects of a combination of isotonic (CI) technique on the balance, muscle fatigue and muscle activities of the quadriceps muscle in the paretic leg of hemiplegic patients. Method: All the subjects received a combined isotonic technique of proprioceptive neuromuscular facilitation (PNF) for about 30 minutes 3 times per week for 6 weeks. The root mean square (RMS) and mid frequency (MF) were recorded by surface electromyography (EMG)(EMG/EP system, OXFORD Medelec, UK) during maximal voluntary isometric contractions (MVIC). The balance ability was measured by a balance system (BIODEX, USA). Result: The RMS of the quadriceps muscle at post-treatment was significantly increased compared to that at pretreatment (p<0.05). Yet there was no significant difference among the three muscles. There were no significant difference in the MF of the vastus lateralis and rectus femoris between pre- and post-treatment, but the MF of the vastus medialis was significantly decreased (p<0.05). There was a significant difference in the vastus medialis and lateralis between pre- and post-treatment (p<0.05). Moreover, the overall stability index at post-treatment was significantly decreased compared to that at pre-treatment (p<0.05). But there was no significant difference between the anterior/posterior and medial/lateral stability indexes. Conclusion: The results of this study indicated that a CI technique of PNF had an effect to improve the balance and muscle activity in hemiplegic patients.

• Journal of the Korean Academy of Clinical Electrophysiology
• /
• v.9 no.2
• /
• pp.7-12
• /
• 2011

Purpose : We studied the correlation between reference voluntary contraction (% RVC) of vastus lateralis (VL) and vastus medialis (VM), Berg balance scale (BBS), and timed-up & go (TUG) test. Methods : We recruited 30 stroke patients from a rehabilitation center at a hospital.? All subjects could walk with or without an assisting device. Subjects were evaluated with % RVC of VL and VM, BBS, and TUG. The data were analyzed using a Pearson correlation coefficient. Results : The % RVC of VL and VM and BBS (p<0.01) showed a significant positive correlation. TUG negatively correlated with % RVC of VL and VM and BBS (p<0.01). Conclusion : Lower extremity muscle activity increases balance and walking ability. We recommend the implementation of lower extremity strength exercises in the rehabilitation of stroke patient.

• Journal of Korean Physical Therapy Science
• /
• v.29 no.3
• /
• pp.21-28
• /
• 2022

Background: Hamstring shortness results in the inappropriate activation of the quadriceps femoris because of the loss of the reciprocal inhibition mechanism. The purpose of this study was to investigate the effects of that activation during lunge exercises on the vastus medialis, vastus lateralis, medial, and lateral hamstrings in participants with hamstring shortness and normal length. Design: Quasi-experimental design Methods: Participants were divided into a hamstring shortness group(n=20) and a hamstring normal length group(n=23), based on a hamstring length test. During lunge exercises, muscle activation of the vastus lateralis, vastus medialis, medial, and lateral hamstrings were measured by electromyography. Results: Each muscle tested was less activated in the hamstring shortness group than in the hamstring normal length group. However, there was no statistically significant difference between the groups (p>.05). Conclusion: Although there was no significant difference between the shortness and normal hamstring groups during short lunge exercise time, longer exercising periods will result in the inappropriate activation of the quadriceps femoris. During lunge exercise, hamstring shortness causes an imbalance activation of quadriceps femoris and hamstring, and continuous hamstring shortness can cause damage on joints of lower limb.

• Journal of Society of Preventive Korean Medicine
• /
• v.11 no.2
• /
• pp.121-132
• /
• 2007

The purpose of this study is to find out the effects of taping therapy on muscle activities between the group of taping therapy treatment and control group before or after exercises. The subjects are 18 S college's healthy male students who do not have any problems in the legs and could bend the knee joint normally. Considering physique, condition of health and capacity for locomotion, 3 groups of each 6 persons for the experimentation were classified. Three groups composed of control group without taping therapy treatment for control group, group I with taping therapy treatment only before the experimentation and group II with taping therapy treatment during 24 hour. before and after the experimentation. EMG MP150 was used to evaluate the parameter of the lower leg's muscle activities the exercise before 5 min. after 10 min. and after 24 hour. for the experimentation. Compared with control group, group I and group II had more increased muscle activities in vastus lateralis and rectus femoris and was statistically significant. And group I and group II also had more increase in muscle activities than control group in vastus medialis, although there was no statistically significant. We found that taping therapy increased muscle activity positively. The application of taping therapy could be used not only for preventive effects for sports man but also therapeutic effects for general people.

• The Journal of Korean Physical Therapy
• /
• v.25 no.2
• /
• pp.81-87
• /
• 2013

Purpose: The purpose of the current study was to examine the effects of electromyography (EMG)-biofeedback training on lower extremity muscle activity and balance of patients with total knee replacement (TKR). Methods: Subjects were randomly allocated to two groups: experimental and control group. Subjects in the experimental group (n=10) were provided with quadriceps setting exercise by EMG-biofeedback (QSE+BF) and those in the control group were provided with QSE. Subjects in both groups were provided with the respective training programs for 20 minutes per session, five times per week, for a period of six weeks. To test significance, data analysis was performed using repeated-ANOVAs. Results: Statistically significant differences in muscle activity of the rectus femoris muscle and the vastus lateralis, and dynamic balance ability were observed in the experimental group, compared with the control group. In comparison of the muscle activity of the rectus femoris muscle and the vastus lateralis, and dynamic balance ability between different training periods within the groups, both groups showed statistically significant differences. Conclusion: EMG-biofeedback training is effective in improving lower extremity muscle activity and balance ability of patients with TKR, and should be effective in patients with other diseases.