Exercise, Play, and Physical Training in Animals

Abstract

Since animal play includes vigorous physical exercise, such behavior has been hypothesized to serve in part as physical training for young animals. Citing recent physiological studies of training responses of muscle, bone, and the cardiopulmonary, endocrine, and nervous systems, I offer seven testable, physiologically based predictions about play, including its behavioral composition, interruption and repetition, age dependence, and phylogenetic distribution. 1 also discuss manipulative, social, and diversive aspects of play which the physical training hypothesis alone does not fully explain.