A. Parrish,M. Lowman, E. Shipman, S. Jerome

University of Alaska Fairbanks, Fairbanks, AK

PURPOSE: There is currently no test to diagnose overtraining syndrome (OTS). Information obtained on correlations between biomarkers and OTS will lead to development of diagnostic tools. This study aims to determine if reported drops in performance in endurance athletes mid- and post-season are associated with significant differences in levels of oxidative stress indicators and antioxidant status markers. METHODS: Fifteen cross country skiers residing at 64ºN were recruited for this study. Blood samples were taken in early Feb. (“mid-season”) and in late Apr. (“post-season”). Concentrations of SOD, nitrotyrosine, NOx, and HNE-4 were determined using ELISA testing. Significance was determined using a paired t-test (mid-season drop v. post-season drop, mid-season no drop v. post-season no drop) an unpaired t-test (drop mid-season v. no drop mid-season, drop post-season v. no drop post-season) with 95% confidence interval. RESULTS: Mean SOD activity increased significantly (P=0.0220) from mid-season (µ=0.02065 u/mL, +/- 0.006477) to post-season (µ=0.04459 u/mL, +/- .005456). Mean SOD activity in athletes who reported a drop increased significantly (P=0.0074) from mid-season (µ=0.01241 u/mL, +/- 0.006469) to post-season (µ=0.05048 u/mL, +/- 0.004688). Mean HNE-4 concentration for all athletes decreased significantly (P=0.0458) from mid-season (µ=0.1486 u/mL, +/- 0.02689) to post-season (µ=0.1133 u/mL, +/- 0.01704). No significant differences in means were found for NOxor nitrotyrosine. CONCLUSION: We found SOD to be significantly higher in the post-season condition. Those reporting a drop during the season lasting three weeks or longer displayed significantly higher SOD activity than those reporting no drop. HNE-4 was significantly lower and for those who did not report a drop mid-season to post-season. The data suggests that those who experience a lasting drop may be more prone to an imbalance in free radical production and elimination. This may provide further evidence of a link between oxidative stress and OTS.

Supported by NIH under award: UL1GM118991, TL4GM118992, or RL5GM118990

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