• Korean Journal of Exercise Nutrition
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• v.23 no.4
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• pp.36-42
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• 2019

[Purpose] The study aimed to determine the effects of bone-specific physical activity on body composition, bone mineral density (BMD), and health-related physical fitness in middle-aged women. [Methods] One hundred eighty-six middle-aged women aged 31-49 years participated in this study. The subjects were divided into tertile groups according to the level of physical activity (low-score group, n=62; middle-score group, n=62; high-score group, n=62). Bone-specific physical activity participation was assessed using the bone-specific physical activity questionnaire. Body composition and BMD were measured using dual-energy X-ray absorptiometry. Health-related physical fitness test included isometric muscle strength (grip strength), muscular endurance (sit-ups), flexibility (sit and reach), and cardiorespiratory fitness (maximal oxygen uptake [VO_2max]). [Results] The high-score group had a significantly higher fat-free mass (p=.045, partial eta-squared value[η_p²]=.033) than the middle- and low-score groups, whereas the high-score group had significantly lower percent body fat (p=.005, η_p²=.056) than the other two groups. Whole-body BMD (p=.034, η_p²=.036) and lumbar BMD (p=.003, η_p²=.060) were significantly higher in the high-score group than in the low-score group. The high-score group performed significantly better for grip strength (p=.0001, η_p²=.101), sit-ups (p=.0001, η_p²=.108), and VO_2max (p=.0001, η_p²=.092) than the other two groups. [Conclusion] The present study suggests that bone-specific physical activity could be useful in improving body composition, BMD, and health-related physical fitness in middle-aged women, significantly enhancing their BMD and health conditions.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.343-351
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• 2015

Objective : The purpose of this study was to investigate the effects in the muscle function following 8-week dead-lift training with Whole-body Vibration(WBV) in rehabilitation for sports players. Method : Twenty young sports players. Each subjects were randomly assigned to a resistance training with Whole-body vibration group(TG, n=10), a resistance training without Whole-body vibration group(CG, N=10). The measurements which physical fitness test and joint torque test were performed before the randomization and after the 4-week and 8-week. The WBV group performed the dynamic Dead-lift exercise on a vibration platform during one minute. The CG group performed the equal training without vibration. The WBV and CON group repeated 5 set and trained two times weekly for 8-weeks. Paired t-test was used to test for differences between the groups at baseline and after 4-weeks and 8-Weeks. And independent t-test was used to test for differences between the groups at TG and CG. All analyses were executed using SPSS software 18.0. The level of significance was set at p<.050. Results : Following the 8-Weeks training sessions, an increase in the back-muscle strength was found to be greater for the TG compared with the CG group(p<.05). Muscle endurance was significantly decreased after training than before training only for the CG(p<.05). Isometric Hip/Lumber Extension/Flextion measurement was found to be significantly greater for the TG compared with the CG group(p<.05). The finding indicates that WBV effects as an efficient training stimulus to enhance muscle function by facilitating neural control trail. Following muscle activation in motor unit synchronization of the co-contraction of the muscles. Conclusion : The results imply that the WBV training may have enhanced muscle function in rehabilitation for sports players.

• Physical Therapy Rehabilitation Science
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• v.13 no.1
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• pp.53-70
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• 2024

Background: The conventional deadlift is a popular exercise for enhancing trunk, core, and lower extremity strength. However, its use in sports medicine is constrained by concerns of lumbar injuries, despite evidence supporting its safety and rehabilitative benefits. To optimize muscle activation using resistive bands in variable resistance therapy, we explored their feasibility in the deadlift. Design: Comparative experimental design Methods: Surface electromyography recorded muscle activity in the trunk and lower extremities during lifting, with normalization to the isometric Floor Lift using Maximal Voluntary Contraction. Kinematics were measured using inclinometer sensors to track hip and trunk sagittal plane angles. To prevent fatigue, each subject only used one of the three pairs of bands employed in the study. Results: Our study involved 45 healthy subjects (mean age: 30.4 ± 6.3 years) with similar baseline characteristics, except for years of lifting and strength-to-years-of-lifting ratio. Various resistance band groups exhibited significantly higher muscle activity than conventional deadlifts during different phases. The minimal resistance band group had notably higher muscle activity in the trunk, core, and lower extremity muscles, particularly in the end phase. The moderate resistance band group showed increased muscle activity in the mid-and end-phases. The maximum resistance band group demonstrated greater muscle activity in specific muscles during the early phase and overall higher activity in all trunk and lower extremity muscles in the mid and end phases of the deadlift (p<0.05). Conclusion: Our findings provide valuable insights into muscle activation with various resistance bands during deadlift exercise in clinical and gym settings. There appears to be a dose-response relationship between increased resistance bandwidth, external load, myoelectric activation, and range.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.2
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• pp.93-101
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• 2016

Purpose: McArdle disease, glycogen storage disease type V (GSD V), is one of the most common adolescent-onset glycogen storage diseases. It is caused by recessive mutations in PYGM encoding myophosphorylase, which is critical to glycogen metabolism. Since only a few korean patients have been reported, we will observe the clinical and genetic features of three korean patients with McArdle disease. Methods: We retrospectively reviewed the medical records of three patients with genetically confirmed McArdle disease, including the results of forearm ischemic exercise test, electromyogram, nerve conduction velocity, muscle biopsy, and PYGM analysis in peripheral leukocytes. Results: All three cases were males and their age of symptom onset was 12, 5, 14 years old, respectively. A high basal level of serum creatine kinase was noted in all three patients. They experienced the recurrent episodes of rhabdomyolysis, but second wind phenomenon was not definite. In muscle biopsy, subsarcolemmal space vacuoles including periodic acid schiff stained materials were found in two patients, while no evidence of glycogen storage disease was found in the other. A total of five different mutations, $p.Arg50^*$, p.Trp798Arg, $p.Arg50^*$, p.Glu779del, $p.Asp511Thrfs^*28$ and p.Phe710del, were found in three patients. Avoidance of isometric exercise, aerobic exercise and glucose intake before each exercise were recommended for all patients. Conclusion: The three Korean patients with McArdle disease showed the typical manifestations of the condition. The most mutations were private. Therefore, identification of more cases with long-term follow-up will be required to understand the clinical and genetic features of this disease among Korean population.

• Physical Therapy Korea
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• v.10 no.3
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• pp.29-40
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• 2003

The purpose of this study was to compare the muscle activity during a push-up on a suspension sling and a fixed support at the same level. Tests were performed on 15 male subjects. Electromyography using a surface EMG recorded the activity of the triceps, pectoralis major, and internal and external oblique muscles during each push-up. EMG activity was recorded at 0, 45, and 90 degrees of elbow flexion in the push-up position on a suspension sling or a fixed support at the same height above the floor (30 cm). The testing order was selected randomly. The subjects were asked to maintain the push-up position with straight knees, hips, and trunk for 5 seconds at each elbow angle. The mean root mean square (RMS) of EMG activity was calculated. EMG activity was normalized using the maximum voluntary isometric contractιn elicited using a manual muscle testing technique. Two-factor repeated measures analysis of variance (ANOVA) was used to compare the average RMS value of EMG activity for each condition. The EMG activity for the pectoralis major, and internal and external oblique muscles during a push-up on a sling was significantly higher than on a fixed support at all angles of elbow flexion (p<.01). There were significant differences in the EMG activity of the pectoralis major and triceps brachii muscles at difference angles of elbow flexion (p<.05). The pectoralis major muscle had the highest EMG activity at 90 degrees of elbow flexion on both the sling and fixed support. The triceps brachii muscle had the highest EMG activity at 45 degrees of elbow flexion on both the sling and fixed support. The internal and external oblique muscles had the highest EMG activity at 0 degrees of elbow flexion, although the difference with angle of flexion was not significant. These results suggest that to improve proximal and trunk stability and muscle strength, push-ups are more useful when performed on a suspension sling than On a fixed support.

• Physical Therapy Rehabilitation Science
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• v.8 no.1
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• pp.45-51
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• 2019

Objective: The purpose of this study was to investigate the muscle activity ratio of the lower limb according to changes in straight leg raise (SLR) test angles on hamstring muscle shortening during squat exercises. Design: Randomized controlled trial. Methods: The subjects were 14 healthy adults who were informed of and agreed to the method and purpose of the study. The participants were classified into SLR groups according to two angles (over $80^{\circ}$ or under $80^{\circ}$) assessed using the SLR tests. After training and practicing the wall squat posture to be applied to the experiment, electromyography (EMG) was used to measure changes in muscle activity during the performance of a wall squat. After stretching, a sequence of pre-stretch tests were performed again, and the active and passive SLR tests were also reconducted; thereafter, a wall squat was performed again by attaching EMG electrodes. The EMG results before and after stretching were compared. Results: The muscle activity of the vastus lateralis oblique muscle increased in both groups. The muscle activity of the vastus medialis oblique muscle decreased in over both group. Rectus femorus activity increased in the under 80-degree groups but decreased in the over 80-degree group. The muscle activity of the biceps femoris muscle decreased after stretching in the over 80-degree group and increased in the under 80-degree group, and the semitendinosus muscle activity after stretching was decreased. The quadriceps-to-hamstring muscle (Q:H) ratio before and after stretching between groups showed that the hamstring muscle ratio decreased after stretching in both groups. Conclusions: The results of this study showed that the Q:H ratio before and after stretching between groups was not significantly different.