• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.139-148
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• 2018

PURPOSE: This study compared the effects of indoor and outdoor environmental changes on the activity of the major lower limb muscles and walking factors in people 40-50 years and those aged older than 70 years. METHODS: Ten middle-aged people in their forties (age:$44.2{\pm}2.7$, BMI:$21.8{\pm}1.8$) and 10 elderly aged more than 70 years (age:$76.4{\pm}5.9$, BMI:$22.2{\pm}1.9$) with a normal walking ability were included. The participants walked 100 m both indoors and outdoors at their own speed. Using a 3D motion analyzer and EMG, the walking speed, angle of the ankle and activity changes of the lower limb muscles were compared. RESULTS: Significant differences in walking speed and peak-plantar flexion angle were observed between the two groups (p<.05). The muscular activity of the gastrocnemius muscle (GCM) was significantly different outdoors in the swing phase between the two groups (p<.05). In the people aged in their forties, the muscular activity of the rectus femoris (RF) was significantly higher outdoors than indoors (p<.05). In the elderly, however, the muscular activity of the RF was lower outdoors than indoors (p<.05). When compared to those in there forties, the muscular activity of the outdoor RF significantly decreased in the elderly group (P<.05). The muscular activity of the biceps femoris (BF) in the elderly decreased significantly outdoors compared to indoors (p<.05). CONCLUSION: For the elderly, increasing the exposure to the new environments or focusing on the performance of repeated movements for gradual speed control and precise movements is required to maintain normal gaits and movements that are less affected by environmental changes.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.123-129
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• 2018

PURPOSE: This study was conducted to investigate the influence of hip abduction angle on the muscle activity of the Gluteus Maximus (GM), Biceps Femoris (BF) and Tensor Fascia Lata (TFL) during Knee Flexed Prone Hip Extension exercise. METHODS: The subjects of this study were 42 healthy individuals. All participant consented to participate in this study. Subjects performed exercise, using the Knee Flexed Prone Hip Extension exercise in three hip abduction position $0^{\circ}$, $15^{\circ}$ and $30^{\circ}$. Subjects rested two minutes, between changing hip abduction position. Data were analyzed using a Noraxon MR-XP 1.08 Master Edition EMG to determine average amplitude, for each angle and muscle. All data were processed by Multivariate analysis of variance (MANOVA). There were a total of three groups. the GM muscle, BF muscle, TFL muscle. RESULTS: GM muscle activity was greatest in the $30^{\circ}$ hip abduction position (p<.05), followed by $0^{\circ}$. Between $0^{\circ}$ and $30^{\circ}$ has significant difference in muscle activity. However, the BF and TFL amplitude were greatest at $0^{\circ}$ hip abduction position followed by $30^{\circ}$. Moreover, the TFL differed significantly between $0^{\circ}$ and $30^{\circ}$, but, BF did not (p<.05). CONCLUSION: Hip abduction at $30^{\circ}$ was found to be the most appropriate position for GM muscle activity.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.105-112
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• 2019

Objective: The main purpose of this study was to investigate the effects of wearing an ankle weight belt while performing gait in water by focusing on the effect of using ankle weights have on the gait kinematics and the muscle activities for developing optimum training strategies. Method: A total of 10 healthy male university students were recruited for the study. Each participant was instructed to perform 3 gait conditions; normal walking over ground, walking in water chest height, and walking in water chest height while using ankle weights. All walking conditions were set at control speed of $4km/h{\pm}0.05km/h$. The depth of the swimming pool was at 1.3 m, approximately chest height. The motion capture data was recorded using 6 digital cameras and the EMG was recorded using waterproof Mini Wave. From the motion capture data, the following variables were calculated for analysis; double and single support phase (s), swing phase (s), step length (%height), step rate (m/s), ankle, knee, and hip joint angles ($^{\circ}$). From the electromyography the %RVC of the lower limb muscles medial gastrocnemius, rectus femoris, erector spinae, semitendinosus, tibialis anterior, vastus lateralis oblique was calculated. Results: The results show significant differences between the gait time, and step length between the right and left leg. Additionally, the joint angular velocities and gait velocity were significantly affected by the water resistance. As expected, the use of the ankle weights increased all of the lower leg maximum muscle activities except for the lower back muscle. Conclusion: In conclusion, the ankle weights can be shown to stimulate more muscle activity during walking in chest height water and therefore, may be useful for rehabilitation purposes.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.53-61
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• 2019

PURPOSE: Forward head posture (FHP) is a head-on-trunk malalignment that results in musculoskeletal dysfunction and neck pain. To improve forward head posture, both the craniocervical flexion exercise (CCFE) and the visual guide (VG) technique have been used. This study compared the immediate effects of CCFE and VG combined with CCFE on craniovertebral angle (CVA), as well as on the activity of the sternocleidomastoid (SCM) and anterior scalene (AS) muscles during CCFE in subjects with FHP. METHODS: In total, 16 subjects (nine males, seven females) with FHP were recruited using the G-power software. Each subject conducted CCFE and CCFE combined with VG in random order. The CVA was recorded using a digital camera and the ImageJ image analysis software. The EMG data of SCM and AS were measured by surface electromyography. A paired T-test was used to assess differences between the effects of the CCFE and VG combined with CCFE interventions in the same group. RESULTS: The CVA was significantly greater for CCFE combined with the VG than for CCFE alone (p<.05). The activity of the SCM and AS muscles was also significantly greater when the VG was combined with CCFE than during CCFE alone across all craniocervical flexion exercise phases (p<.05). CONCLUSION: Use of the VG technique combined with CCFE improved FHP in subjects with FHP compared to CCFE alone.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.71-77
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• 2019

Purpose: The purpose of this study was to compare the level of muscle activation on the cervical erector spinae (CES), lumbar erector spinae (LES), and upper trapezius (UT) according to the sitting postures while using a smartphone in the bathroom. Method: Thirty-two healthy subjects were recruited for this study. The CES, LES, and UT were evaluated by surface electromyography according to two sitting postures while using a smartphone on the toilet seat. A paired t test was performed for the root mean square of reference voluntary contraction (%RVC) comparisons between two sitting postures, and one-way ANOVA was used to compare the three muscle activations within each posture. Results: A comparison between the two sitting postures revealed the muscle activation of both CESs in sitting posture 2 and both LESs in sitting posture 1 to be significantly higher than those of the others. In sitting posture 1, the muscle activation of both LESs was significantly higher than those of the CES and UT. In sitting posture 2, the muscle activation of both CESs was significantly higher than those of the LES and UT. Conclusion: High muscle activation of the CES and LES was observed according to the sitting postures when using smartphone in the restroom. Therefore, long time use of smartphones on a toilet seat should be avoided.

• PNF and Movement
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• v.17 no.1
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• pp.93-101
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• 2019

Purpose: This study aimed to investigate lower extremity muscle activation to the variable weight shift on the affected side of patients with hemiplegia. Methods: Eighteen patients with chronic hemiplegia volunteered to participate in this study. All participants performed three types of weight shift (sideways, forward, and backward) in limits of stability on the affected side. Muscle activation in a paralyzed leg was measured with electromyography on the gluteus medius, tensor fasciae latae, rectus femoris, and biceps femoris; furthermore, the attached area was recommended by SENIAM projects. Each weight shift was performed three times, and then the mean value of the three measurements was analyzed. The data were analyzed by measuring the symmetrically standing position with the reference voluntary contraction (RVC) and was standardized with the percentage of RVC method. Results: No significant difference in lower extremity muscle activation occurred according to the three types of variable weight shift. However, significant differences in lower extremity muscle activation did occur with each weight shift position. In addition, activation increased at the rectus femoris and decreased at the gluteus medius and tensor fasciae latae. Conclusion: Hip abductor muscle strength training and variable weight shifts on the affected side must increase to improve patients'balance and limits of stability.

• Korean Journal of Applied Biomechanics
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• v.31 no.2
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• pp.104-112
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• 2021

Objective: This study aimed to analyze the effects of consecutive whole body vibration through heel raise posture on the center of pressure and electromyography of anterior tibial muscle, lateral gastrocnemius and soleus muscles during single-leg stance. Method: The subjects of this study included 30 healthy males in their 20's, with the following inclusion criteria: no history of orthopaedic medical history, no participation in regular exercises, no history of whole body vibration exercise, and right leg being the dominant leg. The experimental procedure involved pretreatment measurement of eye open single-leg stance, application of whole body vibration for 30 seconds, post-treatment measurement (3 measurements in total). Static and dynamic movements have been measured over 2 separate experiments, with 72 hours gap between the experiments. Static movement involved maintaining single-leg heel raise posture for 30 seconds while applying whole body vibration, and dynamic movement involved heel raise (15 repetitions over 30 seconds) while applying whole body vibration. The strength of applied whole body vibration was 35 Hz frequency and 2~4 mm amplitude. Results: As the single-leg posture after static heel raise posture, mediolateral velocity of the center of pressure at post 2 and post 3 were significantly reduced compared to the pre-treatment measurement. In addition, the percentage for reference voluntary contraction in anterior tibial muscle and soleus and median frequency at anterior tibial muscle and lateral gastrocnemius muscle at post 3 were significantly decreased compared to the pre-treatment value. As the single-leg posture after dynamic heel raise posture, the mediolateral 95% edge frequency of the center of pressure and median frequency at anterior tibial muscle, lateral gastrocnemius muscle, and soleus muscle at post 3 were significantly reduced compared to the pre-treatment value. Conclusion: Acute whole body vibration via static and dynamic heel raise posture have positive effect on mediolateral posture control during single-leg stance.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.133-140
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• 2021

Purpose: This study aimed to compare the relative muscle activity on the erector spinae, gluteus maximus, and hamstring, using a non-visual feedback bridge exercise and a visual feedback bridge exercise with a tension sensor and clinometer. Methods: Twenty-two healthy subjects participated in this study. The study subjects performed bridge exercises without visual feedback, bridge exercises using a tension sensor, and bridge exercises using an inclinometer in the supine position, and the muscle activity of the left and right erector spinae, gluteus maximus, and hamstring muscles was measured while maintaining isometric contraction during the bridge movement. Muscle activity was measured by using surface an electromyography equipment. To standardize the measured action potential of each muscle, the maximum voluntary isometric contraction was measured. The bridge exercise was repeated 3 times for 5s each. Using repeated analysis of variance, we compared the significant difference in EMG activity for each muscle between the three experiments, and all statistical processing was performed using SPSS version 26. The statistical significance level was set at α = 0.05. Results: During bridging exercises, the asymmetry of the muscle activity of the erector spinae and gluteus maximus during visual feedback guiding was lower than that during no visual feedback. However, there was no significant difference. Moreover, the asymmetry of the muscle activity of the hamstring muscles was significantly lower during tension sensor visual feedback than that during no visual feedback (p<0.05). Conclusion: These findings suggest that bridge exercise with visual feedback using a tension sensor and an inclinometer is effective in inducing symmetrical movement. When it is necessary to symmetrically adjust the weight load of both feet during the bridge exercise, it is effective to apply visual feedback using a tension sensor.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.2
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• pp.21-28
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• 2022

PURPOSE: This study examined the effect of changes in the knee angle and weight shifting of the sole on the activity of the lower extremity muscles during bridge exercise. METHODS: The subjects of this study included 20 healthy adult women (mean age 29.8 ± 4.32). The subjects performed the bridge exercise under three weight-shifting conditions general bridge (GB), hindfoot press bridge (HPB), and fore-foot bridge (FPB) and at two knee angles (90° and 60°). During the bridge exercise, the activity of the quadriceps femoris (rectus femoris, vastus medialis oblique, and vastus lateralis) and biceps femoris muscles were measured using an electromyography sensor. RESULTS: In the quadriceps femoris, the muscle activity of HPB and FPB was significantly higher than that of the GB at knee angles of 90° and 60° (p < .05). In the biceps femoris, the muscle activity increased significantly in the order of GB < HPB < FPB, and the knee angle increased significantly at 60° rather than at 90° (p < .05). There was no significant difference according to the knee angle in all muscles except for the biceps femoris. CONCLUSION: These findings suggest that the weight-shifting bridge of sole bridge exercise was more effective in increasing the activation of the lower extremity muscles than the GB.

• 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.