EFFECTS OF ANAEROBIC EXERCISE ON THE IMMUNE-SYSTEM IN 8-YEAR-OLD TO 17-YEAR-OLD TRAINED AND UNTRAINED BOYS

Objectives: To determine the immunologic response to a brief bout of i ntense exercise in children and to determine the effects of prolonged activity and maturation level of the subjects on this response. Study design: We determined counts of leukocytes and their subsets, counts o f lymphocytes and their subsets, and natural killer (NK) cell activity and cell number before and 3 and 60 minutes after a Wingate anaerobic test (WAnT) in 16 male swimmers (9 to 17 years of age) and 17 male no nswimmers (9 to 17 years of age), Subjects were also categorized by pu bertal status based on Tanner staging and by level of physical activit y. The Student t test and analysis of variance were used to determine statistical significance, with values expressed as mean +/- SEM, Resul ts: Three minutes after the WAnT, all children had increases in leukoc ytes (28%), lymphocytes (43%), and NK cells (395%) (p <0.01). Swimmers had less baseline NK cell activity (54 +/- 6 cytolytic units) than no nswimmers (87 +/- 10 cytolytic units) after the WAnT (p <0.01), althou gh both groups showed an increase to similar levels of NK activity 3 m inutes after exercise. Pubertal effects on these responses were not si gnificant. C Conclusions: Our results demonstrate transient leukocytos is, lymphocytosis, and increases in NK cell number and activity in 8- to 17-year-old boys after a brief bout of intense exercise. Formal ath letic training appears to be associated with a lower baseline NK cell activity, and yet such activity is still within the normal range for t his age group. Further investigations are necessary to determine the i mpact of such training on overall health and the ability to fight infe ction.