ABSTRACT
A longitudinal study of the training of young athletes (Rowley, 1992) revealed that junior tennis players aged 12 years (group 1) and 14 years (group 2) were on court for an average of 7 and 10 hours.week-1, respectively. During competition, in contrast to training, the length of time spent on court and the number of matches played, are beyond the control of the player. Even at junior level, tennis matches can extend for many hours. Furthermore, the environmental conditions throughout competition may be hot and humid. It is especially under these conditions that players must rely on their sweating mechanism to lose heat. Children have a lower sweating rate when compared with adults, even when differences in body surface area are taken into consideration (Wagner et al., 1972).
