Influence of Carbohydrate, Intense Exercise, and Rest Intervals on Hormonal and Oxidative Changes

in International Journal of Sport Nutrition and Exercise Metabolism
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This study compared effects of carbohydrate (CHO) and rest on oxidative stress during exercise. Cyclists (N = 12) completed 4 randomized trials at 64% Wattsmax under 2 conditions (continuous cycling for 2 h [C] and cycling with 3-min rest every 10 min for 2.6 h [R]). Subjects cycled under each condition while receiving 6% CHO and placebo (PLA). CHO and PLA were given pre exercise (12 mL/kg) and during exercise (4 mL·kg−1·15 min−1). Blood was collected pre exercise, post exercise, and 1 h post exercise and assayed for F2-isoprostanes, hydroperoxides (LH), nitrite, antioxidant capacity, glucose, insulin, cortisol, and epinephrine. F2-isoprostanes and LH were lower in CHO. Glucose, cortisol, and epinephrine exhibited significant effects, with post exercise levels of glucose higher and cortisol and epinephrine lower in CHO during the R condition. This pattern was identical in the C condition (21). Oxidative stress during cycling was unaffected by use of short rest intervals but was diminished by CHO.

S. McAnulty, Nieman, and Owens are with the Dept. of Health, Leisure, and Exercise Science, and L. Mcanulty and Carper, the Dept. of Family and Consumer Sciences, Appalachian State University, Boone, NC 28608. Morrow is with the Dept. of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232.