Antioxidant restriction and oxidative stress in short-duration exhaustive exercise.
OBJECTIVE
To determine the effect of dietary antioxidant restriction on oxidative stress, antioxidant defenses, and exercise performance in athletes. Oxidative stress has been shown to increase during exercise. To alleviate oxidative stress, a high intake of antioxidant rich foods or supplements may be required in trained athletes.


METHODS
Plasma oxidative stress and antioxidant defenses were examined in 17 trained athletes who underwent two separate exercise tests. Before the initial exercise test participants followed their habitual (high) antioxidant (H-AO) diets. Then they followed a 2-wk restricted-antioxidant (R-AO) diet before the second exercise test. Blood was taken at rest, after submaximal and high-intensity exhaustive exercise, and after 1 h of recovery.


RESULTS
The R-AO diet induced a threefold reduction in antioxidant intake when compared with habitual-antioxidant (H-AO) diets. F(2)-isoprostane concentration (marker of oxidative stress) was significantly higher after submaximal exercise (38%), exhaustion (45%), and 1 h of recovery (31%) when following the R-AO diet compared with the H-AO diet. Rate of perceived exertion was increased on the R-AO diet whilst exercise time to exhaustion was not affected. Total antioxidant capacity and circulating antioxidant concentrations, although not significantly different, tended to be lower when following the R-AO diet.


CONCLUSIONS
Athletes regularly participating in up to 40 min of acute high-intensity exercise may require higher intakes of exogenous antioxidants to defend against increased oxidative stress during exercise, which can be met through an adequate intake of high-antioxidant foods. Thus, there seems no valid reason to recommend antioxidant supplements to athletes participating in acute high-intensity exercise events up to 40 min in duration, except in those known to be consuming a low-antioxidant diet for prolonged periods.
Watson
Trent A
TA
Nutrition & Dietetics, School of Health Sciences, School of Medical Practice and Population Health, University of Newcastle, NSW, 2308, Australia.
Callister
Robin
R
Taylor
Robert D
RD
Sibbritt
David W
DW
MacDonald-Wicks
Lesley K
LK
Garg
Manohar L
ML
D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage*; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D015444:Exercise / Q000502:physiology*; D019803:Glutathione Disulfide / Q000097:blood; D006801:Humans; D008297:Male; D018384:Oxidative Stress; D010101:Oxygen Consumption; D013972:Thyrotropin / Q000097:blood; D014527:Uric Acid / Q000097:blood; D014662:Vasoconstrictor Agents / Q000097:blood; D014810:Vitamin E / Q000097:blood; D019207:beta Carotene / Q000097:blood
D000975:Antioxidants; D014662:Vasoconstrictor Agents; D019207:beta Carotene; D014810:Vitamin E; D014527:Uric Acid; C075750:8-epi-prostaglandin F2alpha; D013972:Thyrotropin; D015237:Dinoprost; D019803:Glutathione Disulfide