Aerobic fitness does not modulate protein metabolism in response to increased exercise: a controlled trial

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Cytokine Response at High Altitude: Effects of Exercise and Antioxidants at 4300 m

Purpose: This study tested the hypothesis that antioxidant supplementation would attenuate plasma cytokine (IL-6, tumor necrosis factor (TNF)-α), and C-reactive protein (CRP) concentrations at rest and in response to exercise at 4300-m elevation. Methods: A total of 17 recreationally trained men were matched and assigned to an antioxidant (N = 9) or placebo (N = 8) group in a double-blinded fashion. At sea level (SL), energy expenditure was controlled and subjects were weight stable. Then, 3 wk before and throughout high altitude (HA), an antioxidant supplement (10,000 IU β-carotene, 200 IU α-tocopherol acetate, 250 mg ascorbic acid, 50 2g selenium, 15 mg zinc) or placebo was given twice daily. At HA, energy expenditure increased approximately 750 kcald-1 and energy intake decreased approximately 550 kcald-1, resulting in a caloric deficit of approximately 1200–1500 kcald-1. At SL and HA day 1 (HA1) and day HA13, subjects exercised at 55% of VO2peak until they expended approximately 1500 kcal. Blood samples were taken at rest, end of exercise, and 2, 4, and 20 h after exercise. Results: No differences were seen between groups in plasma IL-6, CRP, or TNF-! at rest or in response to exercise. For both groups, plasma IL-6 concentration was significantly higher at the end of exercise, 2, 4, and 20 h after exercise at HA1 compared with SL and HA13. Plasma CRP concentration was significantly elevated 20 h postexercise for both groups on HA1 compared to SL and HA13. TNF-α did not differ at rest or in response to exercise. Conclusion: Plasma IL-6 and CRP concentrations were elevated following exercise at high altitude on day 1, and antioxidant supplementation did not attenuate the rise in plasma IL-6 and CRP concentrations associated with hypoxia, exercise, and caloric deficit