Purpose: The purpose of the present study was twofold: first, to assess the effect of prolonged intense exercise on total neutrophil elastase content in endurance-trained cyclists and to determine whether this is associated with postexercise falls in lipopolysaccharide (LPS)-stimulated neutrophil elastase release; and second, to determine the effect of carbohydrate (CHO) ingestion during exercise on these responses.
Methods: In a randomized design, nine trained male cyclists cycled for 2 h at 75% VO(2max) on two occasions with either CHO (6.4%, i.e., 64 g x L-1) or placebo (PLA) beverage ingestion before (5 mL x kg-1), during (2 mL x kg-1), and after (5 mL x kg-1) the exercise. Venous blood samples were obtained at rest, immediately postexercise, and at 1 h postexercise.
Results: After exercise, CHO ingestion was associated with a higher plasma glucose concentration (P < 0.05) and fewer numbers of circulating neutrophils compared with the PLA trial (P < 0.01). Neither exercise nor CHO ingestion affected total neutrophil elastase content, yet LPS-stimulated neutrophil elastase release fell postexercise by approximately 47% on the PLA trial (P < 0.01). Values did not change significantly from preexercise on the CHO trial.
Conclusions: These findings suggest that neither exercise nor CHO-beverage ingestion influences the total elastase content of neutrophils. Therefore, changes in neutrophil elastase content cannot account for the fall in LPS-stimulated neutrophil elastase release after prolonged intense exercise or for the blunting of this response with CHO ingestion.