The validity to estimate changes in body fat and lean body mass (LBM) through total body water and prediction equation based on triceps and subscapular skinfolds was evaluated after a jogging-type training program. Eight obese boys and 11 obese girls had their total body water determined by D₂O dilution method and underwent a complete series of anthropometric measurements at begining and end of a 2-year program. There was no significant reduction in body weight but a significant change in body water as determined by D₂O dilution method. When compared to the body water method, the prediction equation was found to be highly inconsistent. The change values of the prediction equation was significantly higher than the body water method. The actual changes in LBM and % Fat were found to have low correlations with the predicted changes of boys. In addition, the prediction equation gave significantly higher water content of LBM than criterion value.
This suggests that the practice of using prediction equation to estimate actual changes in body composition parameters after physical training program is basically unsound when used for research purposes.

Measurements of heart rates during usual activities, maximal aerobic power and skinfold thickness were carried out as a basic research for the comparative study of the optimal load for successful living in modern society or in future ages. 18 urban sedentary male workers who came to work by car and were 19-38 years of age were selected as subjects.
The mean and S.D. of the maximal aerobic power was 35.8±5.2ml/kg/min, and those of 15 subjects (83%) were below 40ml/kg/min. The means of 12-hr heart rates during usual activities ranged within 71.5-95.0 beats/min. The mean and S.D. of the maximal heart rate during usual activities was 113±10 beats/min; 61±4% of their maximal heart rates during exhaustive exercises. Significant correlation was found between the maximal heart rate during usual activities and maximal aerobic power.

The relations between the power output during exercise and its maximal duration have been investigated on three young male subjects throughout the performance of heavy constant loaded cycling exercises with different intensities, all of which lead to exhaustion during the period from about 20 seconds to about 100 minutes.
The Aerobic Power output (mean total oxygen intake during exercise) develops rapidly with the increase of the maximal duration of exercise amounting to a few minutes in every case, and then, levels off approximately in one case, but declines steadily in the other cases.
The Anaerobic Power output (oxygen debt per endurance time of exercise) decreases rapidly with the increase of the maximal duration of exercise amounting to about 5 minutes, and then decreases slowly.
The relation between the Total Power output (sum of the Aerobic Power output plus the Anaerobic Power output) and its maximal duration is summarized as the two equations : log P = a - b logt, in the case of the t shorter than about 5 minutes, and log P =a′ - b′log t, in the case of the t longer than about 5 minutes. Here, P is the Total Power, tis the maximal duration, and a, b, a′ and b′ are constants. In each subject, the values of the constants a and b respectively. are greater than the a′ and b′
The present investigation was supported by a Grant in Aid for the Miscellaneous Scientific Research from the Ministry of Education.

“Power-Duration Curves” had been measured on three middle aged subjects through-out the performance of heavy constant loaded cycling exercise with different intensities. And the results were compared with the results of previous investigation on young subjects for the purpose to know the properties of the physical work capacity of middle aged man.
The relations between the Total Power output (TP) and its maximal duration (t) is summarized as the following two equations: log TP=a-b·log t, in the case of the t shorter than about 5-6 minutes, and log TP=a′-b′·log t, in the case of the t longer than about 5-6 minutes. The relations between the Anaerobic Power output (AnP) and its maximal duration (t) is also summarized as the two equations: log AnP=c-d·log t, in the case of the t shorter than about 1-4 minutes, and log AnP=c′-d′·log t, in the case of the t longer than about 1-4 minutes. The above equations are applicable to the results of every subjects in each age group, then, the age difference in quality is hardly found. However, the values of the constants a, a′, c and c′ in the above regression equations are respectively lower in the middle aged subjects, the other hand, the age difference is scarcely found in the values of the constants b, b′, d and d. It is also said that the endurance time of the certain Aerobic Power output of the middle aged subjects are shorter than young ones within the experimental region.
It is considered that the one of the reasons, both of the endurance times of the certain Aerobic Power output and Anaerobic Power output are shorter in the middle aged subjects than young ones, is the maximal aerobic power and the maximal anaerobic capacity of the middle aged subjects are lower than young ones.
In this paper, the Aerobic Power is a mean total oxygen intake during exercise, the Anaerobic Power is a oxygen debt per endurance time of exercise. The term of the “Anaerobic” is not most suitable one, however it is used for convenience. The Total Power is defined as the sum of the Aerobic Power plus the Anaerobic Power.

Measurement of maximal aerobic power (MAP), food intake and fatty mass (%Fat) were carried out on 104 males aged 20-49 years living in suburban, rural and moun-tainous districts as a basic research for determing successful living conditions in modern society or in future ages. Measurement of MAP was made indirectly follow-ing the method of Margaria et al. Each subject screened medically was given two different intensities of step up and down exercises, and MAP was calculated from heart rates immediately after exercises and the individual's estimated maximal heart rate. Observation of food intake was conducted by a routine qusetioning, however, checks and counterchecks were made by personal interview until reliable figures had satisfactrily been obtained. %Fat was estimated from skinfold thickness according to the method of Nagamine.
No age differences were found in MAP and 2oFat. Significant negative correlations were found between %Fat and caloric intake per kilogram of body weight per day (P<0.01) and between %Fat and MAP per kilogram of body weight per minute (P< 0.01) . A weak negative correlation was found between %Fat and caloric intake per kilogram of lean body mass per day. A significant positive correlation was found between MAP per kilogram of body weight per minute and caloric intake per kilogram of body weight per day (P<0.05) . Therefore, it is said clearly that physical inactivity rather than excessive caloric intake is associated with the development and mainte-nance of obesity.
Caloric intake and each nutrient intake of UO (Unfit Obese, MAP below 40m1/kg/ min & %Fat above 15%) group and UN (Unfit Non-obese, MAP below 40 ml/kg/min & %Fat below 15%) group were less than those of FN (Fit Non-obese, MAP above 40 ml/kg/min & %Fat below 150) group, respectively, and differences of those intakes between UO group and UN group were not significant. Mean calcium intake of UO group and UN group were less than the recommended allowance value of 10 mg/kg/ day. Both of MAP per kilogram of body weight per minute and per kilogram of lean body mass per minute of FN group were higher than those of UO group and UN group (P<0.01, respectively) . However, differences of mean MAP were not found significantly between UO group and UN group. It is considered that physical inac-tivity is not always associated with obesity, however, it is said from the health scien-tific point of view that fit non-obese man is more desirable than unfit non-obese one.