The purpose of this study was to investigate what differences exist in the effect of practice of overarm throw between the 1st grade and the 4th grade elementary school children. Thirteen boys and 18 girls in the 1st grade and 20 boys and 16 girls in the 4th grade underwent a practice of overarm throw (tennis ball) for 15 minutes, 3 times a week for 8 weeks according to the predetermined instruction. Throwing distance was measured before and after the practice. The mean throwing distance for the 1st grade boys and girls increased 17.0 (±20.2)% and 30.9 (±32.2)% of the initial record, respectively; and those of the 4th grade boys and girls were 20.3 (±22.4)% and 48.7 (±43.2)%, respectively. There was no significant difference in the rate of increase between the 1st and 4th grades, in both sexes. However, significant negative correlation was observed between the rate of increase and the initial record in the 4th grade, while this was not the case in the 1st grade.

The purpose of this study is to examine the mutual relationship among heart rate threshold (HRT), deflection velocity (Vd), maximal heart rate (HRmax), maximal aerobic speed (Saermax), maximal speed (Smax) and running time to exhaustion on the treadmill in Conconi's test in 5 female and 6 male trained distance runners. Each subject have performed 10 Conconi's test to determine the biological valiability of these physiological parameters from the running speed-heart rate relationship.

All Conconi's test except three times had a clear deflection of heart rate performance curve. The coefficients of correlation for each HRT, Vd and HRmax in test 1 and test 2, test 1 and test 10 in 11 subjects existed within an average of 0.745 from 0.938 (P<0.02). The ranges of CV (coefficient of variation) of HRT, HRmax, Vd, Saromax, Smax and running time to exhaustion in each subject were 2.2-9.9%, 0.7-4.2%, 0.8-2.5%, 1.8-5.4%, 1.4-4.5%, 1.6-10.2%, respectively. The proportions demonstrated a statistically significant relationship between a running time to exhaustion and HRT, Vd, HRmax, Saermax and Smax were 9.1%, 27.3%, 72.7%, 9.1%, 27.3%, respectively.

The present results suggets that the HRmax than the HRT, Vd, Saermax and Smax estimated by means of the running speed-heart rate relationship can be used more particularly for the determination of the individual physical condition and/or an index of trainability.

In order to calculate human body density, underwater weight and lung residual volume were measured simultaneously for 31 female track athletes with or without maximum exhalation. Lung residual volumes were 953 ± 155 ml with maximum exhalation and 2350 ± 521 ml without maximum exhalation. No significant difference was found in the calculated body densities with maximum exhalation (1.0582 ± 0.0130 g/ml) and without maximum exhalation (1.0577 ± 0.0122 g/ml). These data indicated that human body density can be measured by underwater weighing method without maximum exhalation.