^31P-MRS spectra were obtained from human first dorsal interosseous muscle during and after the voluntary static abduction of the index finger. Endurance tasks were performed at randomly assigned contraction levels of 15, 20, 30 and 40% of maximal voluntary contraction (MVO. Muscle pH was calculated according to Taylor et al. (1983) using chemical shift between inorganic phosphate (Pi) and phosphocreatine (PCr) on the ³1P-MRS spectra. Mean values of endurance times of static contractions were 7.25, 5.33 and 3.08 minutes for 20, 30 and 40%MVC, respectively. At 15%MVC, all of the four subjects maintained contraction for 30 minutes, and the contractions were terminated at 30 minutes. Muscle pH at the onset of contractions were 7.12, 6.98, 7.01 and 7.08 for 15, 20, 30 and 40%MVC, respectively. At the end of contractions when the subject could not maintain the force level, muscle pH were 6.07, 5.97 and 5.94 for 20, 30 and 40%MVC, respectively. There was no significant difference in muscle pH at the end of contractions between three conditions by one-way ANOVA. In conclusion, there was a critical muscle pH of about 6.0 where static contractions could not be maintained

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An examination was made of the response of respiratory exchange ratio (R), carbon dioxide output (VCO₂) and oxygen uptake (VO₂) to sinusoidal work load with periods (T) of 1 - 16 min in six healthy men to determine whether R response is sinusoidal. The influence of the ratio of the amplitude of VCO₂ to that of VO₂ and the phase lag between them on R response was also studied by computer simulation. The results and conclusions obtained are as follows : 1 ) With decrease in the period, the amplitudes of VO₂ and VCO₂ dropped exponentially, becoming least at T of 1 min (T=1 min). In contrast, the amplitude of R was largest at T= 4 min and subsequently decreased progressively. 2 ) The peak amplitude of R at T=4 min can be explained by the larger phase lag and relatively low of amplitude of VCO₂ to VO₂. 3 ) The smallest amplitude of R at T = I min was due not to the ratio of amplitude or phase lag, but to remarkably smaller amplitudes of VO₂ and VCO₂. 4 ) The phase lag of VO₂ to sinusoidal work load was smaller than that of VCO₂. Phase lag of R was considerably larger than that of VO₂ or VCO₂ 5 ) The response curve of VO₂ and VCO₂ is a sinusoidal curve with the same period as exercise. However, the response of R is not a real sinusoidal but a deformed biphasic curve with a high crest and low trough. The deformity is determined by the phase lag between VO₂ and VCO₂ response and also the ratio of amplitude of VCO₂ to that of VO₂.

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A complative study of %Fat was carried out on Nepali children (Ranging from 6 to 18 years old) to clarify the cause of obesity attended with modernization. 126 males and 79 females who have a natural living style, in rural district (KV) and 166 males and 133 who have a living style affected by the rapid urbanization, in surburban district (BV) were selected as subjects. %Fat was estimated from skinfold thickness according to the method of Nagamine (1975). The results summarized as follows. 1) Mean %Fat of BV in each age were clearly higher than those of KV with coincidental age, especially in male subjects. 2) According to the previous reports (Yoshimizu et al., 1990 ; Ito et al., 1989), it's considered physical activities in the subjects of BV were lower than those of the subjects in KV. But we could not found the nutritional factors to explain the difference of %Fat between BV and KV. From these results, it's considered the difference of %Fat in both districts is due to the difference of their physical activities

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