Background: 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, cross-over 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 hours. Venous blood was sampled at baseline and serially throughout exercise and 24 and 48 hours after exercise. The athletes completed a 24-hour control trial on a separate occasion, in randomised order.
Main outcome measurements: Mean levels of sCD40L and sCD40 during exercise and rest with 95% confidence intervals.
Results: sCD40L levels dropped steadily from baseline (median 4128 pg/ml) to a measured nadir at 24 hours following exercise (median 1409 pg/ml) (p= 0.01). The levels had started to rise again by 48 hours 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.