Effect of Dietary Antioxidants, Training, and Performance Correlates on Antioxidant Status in Competitive Rowers

in International Journal of Sports Physiology and Performance
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The beneficial effects of exercise and a healthy diet are well documented in the general population but poorly understood in elite athletes. Previous research in subelite athletes suggests that regular training and an antioxidant-rich diet enhance antioxidant defenses but not performance.

Purpose:

To investigate whether habitual diet and/or exercise (training status or performance) affect antioxidant status in elite athletes.

Methods:

Antioxidant blood biomarkers were assessed before and after a 30-min ergometer time trial in 28 male and 34 female rowers. The antioxidant blood biomarkers included ascorbic acid, uric acid, total antioxidant capacity (TAC), erythrocyte- superoxide dismutase, glutathione peroxidase (GPx), and catalase. Rowers completed a 7-d food diary and an antioxidant-intake questionnaire. Effects of diet, training, and performance on resting biomarkers were assessed with Pearson correlations, and their effect on exercise-induced changes in blood biomarkers was assessed by a method of standardization.

Results:

With the exception of GPx, there were small to moderate increases with exercise for all markers. Blood resting TAC had a small correlation with total antioxidant intake (correlation .29; 90% confidence limits, ±.27), and the exercise-induced change in TAC had a trivial to small association with dietary antioxidant intake from vitamin C (standardized effect .19; ±.22), vegetables (.20; ±.23), and vitamin A (.25; ±.27). Most other dietary intakes had trivial associations with antioxidant biomarkers. Years of training had a small inverse correlation with TAC (−.32; ±.19) and a small association with the exercise-induced change in TAC (.27; ±.24).

Conclusion:

Training status correlates more strongly with antioxidant status than diet does.

Braakhuis is with the Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand. Hopkins is with the Inst of Sport and Recreation Research, Auckland University of Technology, Auckland, New Zealand. Lowe is with the School of Applied Science, Bay of Plenty Polytechnic, Tauranga, New Zealand.