Compared the spontaneous leg movements of 10 infants with Down Syndrome to those of nondisabled infants matched for chronological age and motor age. Contrary to expectations, no significant difference was found in the frequency of leg movements between the two groups. However, Down Syndrome subjects demonstrated significantly fewer of the most…

Examined longitudinally the effects of infants' age, body dimensions, and experience on the development of crawling. Although most infants displayed multiple crawling postures en route to walking, development did not adhere to a strict progression of obligatory, discrete stages. Duration of experience with earlier forms of crawling predicted the…

Maintains that the "getting into shape" hypothesis of explaining the inverted-U distribution of exercise play across age is likely incorrect. Argues that the biological study of human physical activity play, as recommended by Pellegrini and Smith (1998), will reveal whether physical activity play represents an example of…