Influence of level of habitual activity on physical working capacity and body composition of post-puberal school boys.

The relationships between level of habitual activity, physical working capacity at a heart rate of 170 beats per minute (PWC170), % fat and body size, have been investigated in 85 post-puberal males aged 16 to 18. Percentage of fat was estimated from the sum of four skinfold thickness and body size characterized by: height and weight; arm, chest, calf and thigh circumferences; bicromial and bi-iliac diameters. PWC170 was found to be significantly related to level of habitual activity and to most measures of body size; multiple regression analysis indicates that level of habitual activity and size respectively account for 34% and 37% of the variance in PWC170. When differences in the body weight of the subjects were statistically removed, % fat was related positively to arm circumference, and negatively to height and bi-iliac diameter. There was no relationship between % fat and level of habitual activity. The significance of these results is discussed.