Abstract
The extent and duration of changes in leukocyte subsets, lymphocyte subpopulations,
spontaneous blastogenesis, cortisol, and catecholamines were measured in ten experienced
marathoners, who ran 3 h to exhaustion in a laboratory setting. Blood samples were
taken at baseline, 1 h of exercise, and 5 min, 1.5 h, 6 h, and 21 h of recovery. The
3-h endurance run was associated with significant leukocytosis, granulocytosis, neutrophilia,
monocytosis, and eosinopenia during recovery. All of these parameters except for eosinophils
returned to normal by 21 h of recovery. Total lymphocyte count increased 31% at 1
h of exercise, then decreased 19% at 1.5 h of recovery when compared with baseline
values. T cell count showed no significant changes, but B cell lymphocytosis was measured
at 5 min and 6 h of recovery. T helper/T suppressor ratio (H/S) was significantly
elevated 39% at both 1.5 h and 21 h of recovery due to the decrease in number of T
suppressor cells. Spontaneous blastogenesis was significantly increased 52% by 1 h
of exercise and remained elevated throughout recovery. The increase in cortisol from
baseline to 1.5 h of recovery correlated positively with the increase in both total
leukocyte count (r =0.78, P =0.008) and granulocyte count (r =0.81, P =0.005). Our results suggest that exhaustive endurance exercise in marathon runners
is associated with many significant perturbations in immune system parameters, most
of which return to normal levels at 21 h of recovery.
Key words
leukocyte - lymphocytes - cortisol - catecholamines - running
