Antioxidant supplementation and immunoendocrine responses to prolonged exercise

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Immunology

Background:

• Prolonged exercise can induce significant immunoendocrine changes, including elevated cortisol and interleukin-6 (IL-6).
• Antioxidant supplementation is hypothesized to modulate these responses and mitigate exercise-induced immunodepression.

Purpose of the Study:

• To investigate the effects of daily vitamin C and vitamin E supplementation on immunoendocrine responses to prolonged exercise.
• To determine if antioxidant supplementation reduces exercise-induced immunodepression.

Main Methods:

• Twenty healthy males underwent 4 weeks of either placebo or antioxidant (vitamins C and E) supplementation.
• Participants then completed a 2.5-hour cycling exercise bout at 60% maximal oxygen uptake.

Main Results:

• Antioxidant supplementation significantly blunted the post-exercise increase in plasma cortisol compared to placebo.
• Plasma IL-6 increased similarly in both groups post-exercise.
• Oxidative stress markers showed mixed responses, with TBARS lower in the antioxidant group post-exercise.
• Neutrophil count increased post-exercise, and neutrophil elastase release decreased similarly in both groups.

Conclusions:

• Four weeks of antioxidant supplementation can attenuate the cortisol response to prolonged exercise.
• This effect appears independent of changes in oxidative stress or IL-6 levels.
• Antioxidant supplementation was not effective in modulating exercise-induced neutrophilia or the depression of neutrophil function.