Influence of carbohydrate, intense exercise, and rest intervals on hormonal and oxidative changes.

Dept. of Health, Leisure, and Exercise Science, Appalachian State University, Boone, NC 28608, USA.
International journal of sport nutrition and exercise metabolism (Impact Factor: 1.98). 11/2007; 17(5):478-90.
Source: PubMed

ABSTRACT 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 preexercise (12 mL/kg) and during exercise (4 mL x kg(-1) x 15 min(-1)). Blood was collected preexercise, postexercise, and 1 h postexercise 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 postexercise 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.

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