Abstract
Eleven marathon runners (42.7±2.1 yrs, 54.2±1.8 ml·kg-1·min-1) and nine sedentary controls (44.2±1.2 yrs, 33.3±1.1 ml·kg-1·min-1) were studied during 30 min of rest, a graded maximal treadmill test using the Balke
protocol, and 45 min of recovery to determine the effects of training and acute exercise
on complement and immunoglobulin levels. Three baseline and five recovery blood samples
were obtained in addition to repeated 5-min samples during exercise. Data for the
exercise period were analyzed using a multiple regression approach to repeated measures
ANOVA to allow comparison between groups on a percent V̇O2max basis. Groups did not differ during any of the three phases for IgG, IgA, or IgM.
Resting levels of complement C3 (0.89±0.05 vs 1.27 ± 0.10 g/L, P < 0.001) and C4 (0.19
± 0.02 vs 0.29±0.03 g/L, P < 0.001) were significantly lower in athletes than in controls.
Exercise complement C3 [F(1,18) = 14.1, P = 0.001] and C4 [F(1,18) = 7.6, P = 0.013],
and recovery complement [F(1,18) = 19.4, P < 0.001] and C4 [F(1,18) = 13.5, P = 0.002]
were also lower in the athletes than in sedentary controls. Acute increases during
exercise were not associated with changes in catecholamines or Cortisol. These data
suggest that blood concentrations of C3 and C4, but not IgG, IgA, or IgM, are decreased
during rest, graded maximal exercise, and recovery in marathon runners in comparison
with sedentary controls.
Key words
complement - immunoglobulin - exertion - catecholamines - Cortisol
