Semester

Spring

Date of Graduation

2009

Document Type

Thesis

Degree Type

MS

College

School of Medicine

Department

Exercise Physiology

Committee Chair

G. Gregory Haff.

Abstract

Purpose. To determine if 5 days of antioxidant supplementation coupled with a pre-ride antioxidant/energy supplement improves cycling performance or reduces oxidative stress in trained cyclists.;Methods. Eight well-trained cyclists participated in a double-blind cross-over placebo-controlled study. Maximal oxygen consumption (VO2Max), peak power output (WMax) and total work during a 15-minute time trial were determined. Subjects consumed an antioxidant supplement (S) or a placebo (P) for 5 days before each trial and a pre-exercise supplement or isocaloric placebo (4 kcal·kg-1) 45 minutes before each trial. Subjects performed an endurance ride of 90 minutes followed immediately by a time trial requiring accumulation of total work equal to the initial time trial.;Results. The GSH:GSSG ratio remained constant prior to both experimental trials, while resting total GSH concentrations exhibited a main effect (p = 0.038) in response to step-one of the supplement protocol for basal (S: 1020.2 +/- 135.8 micromol·L-1; P: 1000.2 +/- 252.9 micromol·L-1) vs. pre-endurance (S: 979.2 +/- 155.1 micromol·L-1; P: 867.3 +/- 231.2 micromol·L-1). During the endurance ride, no differences were observed in average power (S: 224.0 +/- 36.5 W; P: 219.1 +/- 19.2 W), oxygen consumption (S: 2.8 +/- 0.4 L·min -1; P: 2.8 +/- 0.4 L·min-1), heart rate (S: 148.4 +/- 3.5 beats·min-1; P: 146.3 +/- 4.5 beats·min-1), or GSH:GSSG ratio (S: 1.4 +/- 0.7; P: 1.4 +/- 0.9). During the time trial tests, supplementation did not lead to any differences between average power (S: 303.6 +/- 59.2 W; P: 306.1 +/- 47.0 W), oxygen consumption (S: 3.5 +/- 0.4 L·min-1; P: 3.3 +/- 0.6 L·min -1), heart rate (S: 171.1 +/- 6.5 beats·min -1; P: 170.3 +/- 3.5 beats·min -1), or GSH:GSSG ratio (S: 1.1 +/- 0.6; P: 0.9 +/- 0.7).;Conclusion. Consuming an antioxidant supplement for 5 days coupled with a pre-exercise antioxidant/energy supplement does not result in significant improvements in cycling performance. However, the multiple-step supplementation may attenuate oxidative stress during the cycling bout when compared to a placebo, possibly due to the maintenance of glutathione levels.

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