Effects of laboratory versus field exercise on leukocyte subsets and cell adhesion molecule expression in children

In adults, exercise is a powerful and natural stimulator of immune cells an d adhesion molecules. Far less is known about these exercise responses duri ng childhood and whether or not exercise in real-lif activities of healthy children might influence immune responses. We compared laboratory exercise (10x2 min periods of heavy. constant intensity, cycle ergometer exercise wi th I min rests between exercise in nine subjects, aged 9-15 years) with fie ld exercise (90 min soccer practice in nine different subjects. aged 9-11 y ears). Blood was sampled before both protocols, 5 min after the 30 min labo ratory protocol. and 10-15 min after the 90 min field protocol. Both field and laboratory exercise protocols led to significant (P < 0.05) increases i n granulocytes, monocytes, and all lymphocyte subpopulations. The mean (SEM ) increases were similar for the two protocols except for the significantly greater increase in laboratory compared with field protocols for natural k iller cells [142 (39)% vs 12 (16)%, P < 0.001] and monocytes [64 (22)% vs 3 2 (19)%. P < 0.001]. Both protocols significantly influenced adhesion molec ules (such as CD54) which have not been previously studied in children. How ever. the adhesion molecule CD8(+)CD62L(-) increased to a significantly (P < 0.001) greater extent in the laboratory [101 (25)%] versus field [34 (25) %] protocol. Finally, the density of CD62L on lymphocytes significantly dec reased with laboratory exercise but showed no change in the field protocol [-20 (3)% vs -3 (3)%. P < 0.001]. The rapid and substantial immune response in both laboratory and field protocols suggests that exercise stimulation of the immune system occurs commonly in the real lives of children and may play a role in their overall immune status.