자연과학편 : 스피드 조건에 따른 Knee Extensor Muscles의 Concentric과 Eccentric Contraction시 근육활동 형태의 변화

김창국(ChangKookKim) 한국체육학회 1993 한국체육학회지 Vol.32 No.1

To investigate the muscle firing timing patterns during the concentric and eccentric contractions may help us understand muscle contraction mechanism in terms of the number of moter units firing, firing frequency and amplitude of the active muscle. To determine how the muscle firing patterns change as the speeds are varied during both concentric and eccentric muscle contraction may answer the question such as which type of muscle contraction is superior to another one and why.The purpose of this study was to investigate the muscle timing patterns during concentric and eccentric contraction of knee extensor muscle and to determine how the muscle activity timing patterns change as the angular speeds are varied.Ten healthy subjects each performed the concentric and eccentric movement with the leg lift exercise machine to be investigated muscle firing patterns change as the speed conditions vary at 60% of the maximum load.The IEMG activity in each of the rectus femoris and vastus medialis was measured for each trial.The ANOVA test revealed no significant difference in mean and peak values of eccentric muscle contraction across the three different speed condition(60, 120, 180deg/s) from the rectus femoris and vastus medialis. The same results were revealed in mean and peak values of concentric muscle contractions from the recuts femoris, however the same comparision from the vastus medialis muscle there is a significant difference in mean muscle activity(p<.05).In the comparison between the eccentric and concentric muscle contractions at each speed condition, there was a significant difference. The concentric muscle contractions showed significantly more muscle activity than the eccentric muscle contractions(p<.05).The comparison of muscle activity between the rectus femoris and vastus medialis revealed that the rectus femoris showed greater muscle activity than vastus medialis.In conclusion, the results indicated that speed is not a significant factor in influencing the mean and peak values in eccentric muscle contractions. Also, the data supports that eccentric muscle contractions at 60, 120, 180deg/s have less muscle activity than concentric muscle contraction.

자연과학편 : 속도 및 부하 조건에 따른 슬관절 신전근의 단축성 수축과 신장성 수축시 근육활동 형태에 대한 근전도 분석

김창국(ChangKookKim) 한국체육학회 1995 한국체육학회지 Vol.34 No.2

The purpose of this study was to investigate the muscle activity patterns during concentric and eccentric contraction of the knee extensor muscle(m. rectus femoris) and to determine how the muscle activity patterns change as the angular speeds(60, 120, 180˚/sec) and loads(30 & 60% max load) are varied. Ten healthy university students(male) performed the concentric and eccentric movements with a leg extention machine. The EMG activity was recorded from the m. rectus femoris with a Lafayette Instrument EMG Model 76409 and pairs of surface electrodes at a sampling rate of 1000 ㎐. The EMG data was scaled based on the standardized EMG values(MVC) on m. rectus femoris and a ANOVA Repeated Measures & Sheffee’ test(p<.05) was employed for statistic analysis. The results revealed that the IEMG activity of concentric muscle contraction on 30% max load increased with increasing knee angular velocity from 60˚/sec to 120˚/sec & 180˚/sec(p<.05). but eccentric contraction did not. The concentric contraction had higher IEMG activity than eccentric contraction on every conditions(p<.05). The IEMG activity during eccentric contractions at 120˚/sec and 180˚/sec was greater in the 60% max load than in the 30% max load (p<.05).In conclusion, the results indicated that speed is not a significant factor in influencing the IEMG activity in eccentric muscle contractions. Also, the data supports that the eccentric muscle contraction at 60-180˚/sec have less IEMG activity than concentric muscle contractions and the loads had greater effects on the eccentric contraction than on the concentric contraction.

운동생리학 : 50대 이상 성인 남녀의 신체 총 지방량 산출을 위한 인체 측정법 및 생체 전기 저항 측정법의 혼합 모형 개발

김명기(MyungKiKim),김창국(ChangKookKim) 한국체육학회 2001 한국체육학회지 Vol.40 No.2

본 연구는 50대 이상 성인들의 신체 총 체지방량 추정 방식을 개발하는 것이다. 이를 위하여 50세 이상 성인남녀 124명을 대상으로 이중 에너지 흡수법(DEXA), 인체 측정법, 그리고 생체 전기 저항법(BIA)으로 각각 총 체지방량을 측정하였다. 또한 이중 에너지 흡수법(DEXA)에 의한 체지방량을 준거로 인체 측정법, 생체 전기 저항 측정법(BIA), 그리고 인체 측정법과 생체 전기 저항 측정법(BIA)을 혼용한 방법 등과의 상관관계를 분석하였으며, 가장 정확한 체지방량의 측정을 위하여 이중 에너지 흡수법(DEXA)에 의한 값을 종속 변수로 하고 각각의 방법에서 채택된 변수들을 독립 변수로 하여 중다회귀분석(multiple regression)을 실시하여 추정식을 구하고, 그 설명력을 비교하였다. 본 연구의 결과 이중 에너지 흡수법(DEXA)으로부터 얻은 신체 총 체지방량을 종속 변수로 설정하여 인체 측정법을 이용하였을 때(남 : r² = 0.843, 여 : r² = 0.907)보다 생체 전기 저항 측정법(BIA)을 이용하였을 때(남 : r² = 0.885, 여 : r² = 0.927) 신뢰성은 더 향상되었으며, 인체 측정법과 생체 전기 저항 측정법(BIA)을 혼용한 방법을 이용하였을 때(남 : r² = 0.913, 여 : r² = 0.940) 남녀 모두에서 신뢰성 가장 높은 것으로 나타났다. 이와 같은 연구결과들은 50대 이상 성인 남녀들의 신체 총 체지방량을 추정하기 위한 방법으로 인체 측정법과 생체 전기 저항 측정법(BIA)을 혼용한 방법이 현장에서 간편하게 이용할 수 있는 신뢰성 있는 측정 도구라는 것을 제시해주고 있다. The purpose of the study were to develope age and sex specific regression equation for prediction of total body fat by DEXA(independent variables) in > 50 y-old subjects by means of the mixed model of BIA and anthropometry. For the purpose of study, 124 elderly subjects(male:56, female:68) were measured. The results are as follows:First, The mixed model of anthropometry and BIA showed the highest correlation with DEXA both man(r² = 0.913) and women(r²= 0.940).Second, BIA variables(man: r² = 0.885, women: r²= 0.927) increased the correlation coefficients than using anthropometry(man: r² = 0.843, women: r² = 0.907).Third, The value of total body fat obtained DEXA showed the highest correlation with the Weight and hip circumference measured by anthropometry.These findings suggest that our equations developed by the mixed model of anthropometry and BIA may improve prediction of total body fat in >50-y-old man and women.

운동생리학 : 키네시오 테이핑 적용 후 시간경과에 따른 요부근력의 최대 발현 시점

김명기(MyungKiKim),이성기(SungKiLee),김창국(ChangKookKim) 한국체육학회 2005 한국체육학회지 Vol.44 No.5

This study was designed to determine the appropriate application time of Kinesio taping for athletes to improve their maximum strength and to provide systematic information that can be widely applicable to the athletics, and consequently, to improve their performance in sports competitions. Ten healthy college students in the Department of Sport and Leisure Studies at ChoongNam were screened, and individuals with a history of previous injury or surgery in their nerve, muscle, and skeletal systems, such as paresthesia and motor disorder, were excluded from this study. Subjects were taped over Rectus abdominis and Erector spine, and the changes in strength in the lumbar were measured before taping (NTmt) and then at three different time scales, immediately after taping (T0mt), 24 hours (T24mt), and 48 hours (T48mt) after taping using the Apsun lumbar extension machine. Experimental data in terms of changes in strength before and after taping were compared with the average (M) and standard deviation (SD) for each parameter using statistical package, SPSS 12.0. All statistical analyses were performed using repeated analysis of variance and Tukey's post-hoc test at a preset level of significance of α = 0.05. The results were as follows:1. Strength in the lumbar was greatly improved after taping at all three different time scales (immediately after taping, 24 hours and 48 hours after taping) as compared to before taping.2. Changes in maximum strength in the lumbar according to time lapse showed statistically significant difference. At the time of 24 hours after taping, change in strength was maximized, which then decreased.3. In terms of strength in the lumbar according to time lapse, the maximum strength was achieved 24 hours (T24mt) after taping.This study shows that strength can be improved by Kinesio taping and changed with time lapse. In particular, strength is greatly changed and achieved 24 hours after taping. Therefore, it is recommended that taping be applied 24 hours ahead of the competitions to effectively improve the strength and performance.