In this study the effects of endurance exercise on cardiorespiratory functions and performance in developing age were exemined in 12 year old boys. Sujects were consisted of 11 boys who had been participating in training for soccer more than 2 hours a day for 6 days per week (S) and 10 non-participating boys for control (C) . Maximal oxygen uptake (Vo₂max), maximal heart rate (HRmax) and maximal cardiac output (Qmax) by acetylnerebreathing method were measured on the exercise on a treadmill. Five minute run was also administered.
Significant differences were found in Vo₂max (p<0.05), values of which were 2.13±0.07 1⋅min^-1 for S. and 1.86±0.08 1⋅min^-1 for C., respectively, and in Qmax (p<0.001), values of which were 17.9±1.41⋅min^-1 for S. and 12.4+0.71⋅min^-1 for C. G., respectively. There were no significant differences in HRmax and V_E between both groups. Values of stroke volume and V_E/Vo₂max were significantly higher for S.. Performances on 5 minute-run were 1164 m for S. and 1083 m for C, which showed significant difference (p<0.01) . Significant correlationship (r=0.746, p<0.001) was obtained between Vo₂max and Qmax. It was also found that the higher Vo₂max was, the higher Qmax was attaind.

Little is known about the effects of aerobic exercise on cardiac structure in children. Echocardiographic study was performed at rest in 38 boys aged 11-12 (18 soccer players and 20 untrained) . Soccer players had significantly increased left ventricular end-diastolic dimension (43.6±2.8 vs 40.1±2.8 mm) and left atrial dimension (27.7±3.7 vs 23.0±2.8 mm) . There was no difference in interventricular septum and left ventricular posterior wall thickness between the two groups, these data show that intensive aerobic exercise may influence on cardiac structure in children.

Studies were made on the physical fitness and morphological development of 47 high ranking sumo wrestlers who are considered to possess gigantic physique and great strength.
Morphological measurements.
1) The average body height was 180.2cm which when compared to the average Japanese is remarkably tall, however, when considering the tendency for the first rate athletes in Judo, boating, baseball, and basket ball to become taller, recently, this is not particularly noteworthy (Fig.1) .
2) The average body weight was 122.3kg, and the average of the Rohrer's index was 210.5. This is remarkable and may be considered to be a characteristic of the sumo wrestlers (Table 1, Fig. 2) .
3) The development of the circumf erential measurements when compared to that of the long axis of the body was remarkable : waist girth, 114.9cm, and hip girth 115.7cm. The skinfold thickeness was 109.9mm which is remarkably thick. This nearly abnormal development of subcutaneous fat is a special characteristic of sumo wrestlers.
Physical fitness.
4) The average back strength was 181.2kg, and the average grip strength was 47.9 kg, which are unexpectedly small and inferior to those of the boating and heavy weight lifting Olympic athletes. The method of measurement of muscle strength may be somewhat problematic, however, the development of the muscles was surprisingly poor. (Table 4)
5) The sumo wrestlers were also remarkably poor in tests requiring body movement, such as, vertical jump (47.9 cm) and side step test (35.1 times) . These values are far inferior to those of athletes in other sports, and are even inferior to those of the average Japanese of comparable age. (Table 4)
6) However, in spite of their obesity, the sumo wrestlers were comparable to the athletes of other sports in body flexibility and response time. (Table 4)
7) Obese subjects are said to have weak respiratory function. The sumo wrestlers under observation had an average vital capacity of 4918.6m1 indicating a remarkably low value for their large physique.
8) The average points for the step test was 49.4 indicating a lower value than the average Japanese of comparable age.
9) A follow-up study of the measurements made during the past 4 years was made on a few Sekitori. Although no change was noted in body height, marked increases in body weight and circumferential measurements were observed. (Fig. 4)
10) When the higher ranking wrestlers were compared with the lower ranking wreatlers, it was found that, morphologically, the higher ranking wrestlers were superior in body weight and circumferential measurements, however, no significant difference was found in the functional aspect (Fig. 5, 6) . These facts suggest that morphological superiority is an important factor in winning a sumo match.
11) From the foregoing, it may be inferred that the special characteristic of the sumo wrestler is their well developed morphological features, especially girth, however, they are far inferior to athletes of other sports in their functional aspect. These points suggest that more consideration should be made on the sumo wrestlers' method of training and also on their mode of living.

The relationships between running performances (200 m running time and 5-min run) and VO₂max, Lactate Threshold (LT), or percent fat were investigated on 11-12-year old boys. Subjects were 21 control boys (group C) and 21 soccer boys (group S) . Mean 200 m running time in group S was significantly better than that in group C. Mean distance of 5-min run in group S was significantly longer than that in group C. No significant difference was found between mean running speed of 5-min run and mean speed at exhaustion in LT experiment. In group C, 200 m running time correlated significantly with VO₂max. In group S, faster runners showed higher peak post 200 m run lactate concentration. 5-min run correlated significantly with VO₂max for group C, group S and all subjects combined. LT correlated significantly with 200 m running time and 5-min run. No significant relation was found between running petformances and percent fat. It is suggested that VO₂max and LT determine, in part, boy's running performances, but percent fat do not.