Environmental Temperature and Exercise Induced Oxidative Stress

Abstract

Exercise is a fundamental challenge to our homeostatic environment. Notably, this challenge presents itself as an overproduction of Reactive Oxygen Species (ROS) and an inability to convert these free radicals to less reactive molecules. PURPOSE: The purpose of this study was to investigate the effects of varying environmental temperature on the blood oxidative stress associated with exercise. METHODS: Recreationally active participants (n = 12, age 27 ± 5, wt 171.7 ± 0.7 lbs) were recruited to conducted the study. Baseline testing produced average VO2MAX = 56.7 ± 5.8 ml/kg/min and max power output (WMAX) = 300 ± 39 W (on cycle ergometer with electronic breaking). Participants completed a series of 3 exercise sessions, each consisting of a 1 hr ride at 60% Wmax, in a hot (H, 33°C), cold (C, 7°C), and neutral environment (N, 20°C). 12-hour fasting prior to testing, diet and exercise records were used to control for extraneous variations. Participants remained in a supine position in the same temperature room throughout a 3 hr recovery. Blood samples were collected pre-exercise, 0:00 post-exercise, 1:00 and 2:45 post exercise. Samples were analyzed for oxidative stress markers using Ferric Reducing Ability of Plasma (FRAP), Trolox Equivalent Antioxidant Capacity (TEAC), and Protein Carbonyls (PC). RESULTS: FRAP was elevated in all conditions over pre (H +13%,C +11%,N +10%) remaining elevated at 3 hr. PC's were elevated in H post (H +36%) and 3 hr post (H +44%). TEAC was elevated in H at (post +10%, 1 hr +11%, 3H 11%) in C (1hr 4%), and N (1Hr +9%). H was significantly elevated from C and N at 3 hr. CONCLUSIONS: As evidenced by TEAC, exercise in a hot environment elicits more blood oxidative stress than cold and neutral. Sponsored by Air Force Surgeon General #FA7014-09-C-0010-P00001