• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.832-839
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• 2007

In this study, a new bicycle system was developed to improve muscular strength using the Magneto-Rheological(MR) rotary brake. The friction load of the MR rotary brake is adjusted according to muscle strength of the subjects. The characteristic of muscular strength was studied with various friction loads of MR rotary brake. The friction load was occurred with the current, applied to the MR. rotary brake. Experiments was composed of several cycling trials for various friction loads. In training programs involving muscle improvement, it is necessary to confirm muscle activity and fatigue. To measure the muscle activity and fatigue, EMG signals of rectus femoris (RF), biceps femoris (BF), tensor fasciae latae (TFL), vastus lateralis (VL), vastus medialis (VAS), gastrocnemius (GAS), tibialis anterior (TA) and soleus (SOL) muscles were collected with surface electromyography and analyzed into time and frequency domain. The experimental results showed that the muscle activity according to the applied current to the MR rotary brake was significantly different. The more the current was applied, the higher value of the integrated EMG (IEMG) was obtained. Especially, the magnitude of IEMG of the RF, BF, TFL and VL varied in direct proportion to the current. However, there was not significant in the median frequency as the cycling time continue.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.113-121
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• 2007

The purpose of this study was to determine the effect of three different plates($0^{\circ}$, $10^{\circ$}, $20^{\circ}$)under heels on the lower limb muscles and erector spinae during squat exercise. Ten high school korean traditional wrestling players(age: $18.5{\pm}0.7$, weight: $1972.2{\pm}128.5N$, height: $177.8{\pm}6.0cm$, weight of barbell: $1004.5{\pm}132.4N$) performed squat exercise using three different tilting plates under heels at a cadence of 40beats/sec with 80% one repetition maximum load. Surface electrodes were placed on the participants' left and right erector spinae, and rectus femoris, vastus medialis, vastus lateralis, tibialis anterior, biceps femoris, medial gastrocnemius, and lateral gastrocnemius in the right lower extremity. One S-VHS camcorder(Panasonic AG456, 60fields/s) was placed 10m to the side of the participant. To synchronize the video and EMG data, a synchronization unit was used for this study. Average and Peak IEMG values were determined for each participant. For each variable, a one-way analysis of variance was used to determine whether there were significant differences among three different tilting plates under heels. When a significant difference was found in plates type, post hoc analyses were performed using the Tukey procedure. A confidence level of p<.05 was used to determine statistical significance. As a result of this study, maximum nEMG values of the tibialis anterior in $0^{\circ}$ plates was significantly higher than the corresponding values for the other plates during the knee extension. This increased activation in the tibialis anterior muscle indicates an increase in displacement of center of gravity of body. It is very likely that additional muscle activation are needed to stop the forward and backward movement. The results also showed that muscular activities of quadriceps femoris and erector spinae were decreased with increasing angle of plates. This suggests that increasing angle of plate may help to sustain the balance and posture of squat exercise. It is considered that very few significant differences were found among three different plates($0^{\circ}$, $10^{\circ}$, $20^{\circ}$) since elite players with much experience in squat exercise, were chosen as a participant of this study. In order to obtain meaningful results regarding the tilting angle of heel plates in squat exercise, kinetic and 3D kinematic analysis will be needed in the future study.

• Research in Community and Public Health Nursing
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• v.6 no.1
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• pp.55-73
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• 1995

An Effect of Muscle Strength Training Program on Muscle Strength, Muscle Endurance, Instrumental Activities of Daily Living and Quality of Life in the Institutionalized Elderly Recent statistics shows that the aged are the fastest growing segment of our population by increasing life span. The age group of over 60 shows multiple health problems and the most serious handicapping problem of these. are related to the changes in muscular skeletal system. With aging, people lose. their muscle mass and muscle strength resulting from biological changes and physical inactivity. Studies documented a 30-50% loss of muscle mass in an advanced age and thus, ordinary life activities can be seriously affected due to weakened muscle strength. Preservation of muscle strength of lower limb is especially important in the aged. Since it is readily affected from reduced physical activity in old age, sometimes to the detriment of moving or walking. So muscle strength exercise program designed for the elderly to improve leg muscle strength and leg muscle endurance. The research design used was nonequivalent control group pretest - protest design. The purposes of this study were to test the effect of muscle strength exercise program utilizing Leg Press on muscle strength, muscle endurance, instrumental activities of daily living(IADL), cognitive perceptual variables and quality of life. Forty nine subjects participating in this study consisted of twenty four male and twenty five female. Twenty four experimental group subjects were selected from C-institution in Chung Buk province, and twenty five control group subjects were selected from O-institution in Chung Nam province. The mean age of subjects was 72.8 years. Muscle strength training program utilizing Leg Press for the experimental group was carried out three times a week for 9 weeks. The data was collected from August, 1993 to October, 1993. Data were analyzed with $X^2-test$, t-test, ANCOVA test, Kruskal Wallis 1-Way ANOVA test using SPSS PC program. Results were obtained as follows : 1) The experimental group showed significantly higher scores on muscle strength (leg lift strength, back lift strength and grip strength) and muscle endurance than control group after the experiment $\ulcorner$F=52.35(p=.001), F=54.07(p=.001), F=6.97(p=.011), F=18.17(p=.001)$\lrcorner$ 2) Experimental group were significantly higher scores on IADL than control group(F=7.51, p=.009). 3) Experimental group showed significantly higher scores on economical state and self esteem aspects of the quality of life scale than control group $\ulcorner$F=10.59(p=.002), F=6.97(p=.011)$\lrcorner$. But there were no differences in emotional state, physical and functional state and relationship with reatives in the quality of life between groups. 4) Scores on IADL showed a significant difference with the level of muscle strength and muscle endurance $\ulcornerx^2=7.73(p=.025),\;x^2=8.86\;(p=.011)\lrcorner$ 5) Scores on self esteem and physical and functional state aspects of the quality of life scale showed a significant difference with the level of IADL $\ulcornerx^2=11.39(p=.003),\;x^2=9.02(p=.011)\lrcorner$. 6) Scores of experimental group after the experiment in cognitive perceptual variables (perceived benefit on exercise, perceived health status, self efficacy, emotion on exercise) were significantly higher than those of control group $\ulcorner$F=32.09(p=.001), F=5.07(p=.029), F=20.63 (p=.001), F=30.38(p=.001)$\lrcorner$. As a result of this study, the effect of strength training exercise program with Leg. Press had improved muscle strength, muscle endurance, IADL, and the perception of self esteem, physical and funtional state, and economical state. Thus strength training program could be beneficially applied for the prevention of disablity and promotion of health and wellbeing in the aged easily and safely. The subjects in the experimental group have maintained their exercises till six months after the cessation of the experiment. This seem to illustrate that changes in cognitive perceptual variables and the improvement in health status have reinforced motivation for the continuation of voluntary exercises. A further study is necessary to determine the factors affecting maintainance of muscle strength exercise and to assess the effect of weight training program on bone density.