Abstract
Background Soluble CD40 ligand (sCD40L) is a powerful marker of cardiovascular risk. Exercise is known to decrease cardiovascular risk, but the impact of ultra-endurance exercise on sCD40L responses is unknown.
Objective To examine the relationship between ultra-endurance exercise in trained athletes and levels of sCD40L and its natural ligand sCD40.
Design Control-trial, crossover design, exercise intervention study of sCD40L and sCD40 levels.
Setting Outdoor exercise and laboratory testing, single centre study, School of Physical Education, University of Otago, New Zealand.
Participants Nine trained ultra-endurance athletes.
Interventions Athletes exercised (cycled and jogged) for 17 of 24 h. Venous blood was sampled at baseline and serially throughout exercise and 24 and 48 h after exercise. The athletes completed a 24 h control trial on a separate occasion, in randomised order.
Main outcome measurements Mean levels of sCD40L and sCD40 during exercise and rest with 95% CIs.
Results sCD40L levels dropped steadily from baseline (median 4128 pg/ml) to a measured nadir at 24 h following exercise (median 1409 pg/ml) (p=0.01). The levels had started to rise again by 48 h after exercise. When measured as a group, sCD40L levels remained constant during a control rest period. sCD40 levels remained constant on both exercise and control days.
Conclusion Ultra-endurance exercise lowers the levels of the cardiovascular risk marker sCD40L in athletes. These results raise the possibility that exercise-induced changes in sCD40L may provide one of the mechanisms by which exercise lowers cardiovascular risk.