Antioxidant supplementation does not alter endurance training adaptation.
BACKGROUND
There is a considerable commercial market, especially within the sports community, claiming the need for antioxidant supplementation. One argument for antioxidant supplementation in sports is that physical exercise is associated with increased reactive oxygen and nitrogen species (RONS) production, which may cause cell damage. However, RONS production may also activate redox-sensitive signaling pathways and transcription factors, which subsequently, may promote training adaptation.


OBJECTIVE
Our aim was to investigate the effects of combined vitamin C and E supplementation to healthy individuals on different measures of exercise performance after endurance training.


METHODS
Using a double-blinded placebo-controlled design, moderately trained young men received either oral supplementation with vitamins C and E (n = 11) or placebo (n = 10) before and during 12 wk of supervised, strenuous bicycle exercise training of a frequency of 5 d x wk(-1). Muscle biopsies were obtained before and after training.


RESULTS
After the training period, maximal oxygen consumption, maximal power output, and workload at lactate threshold increased markedly (P < 0.01) in both groups. Also, glycogen concentration, citrate synthase, and beta-hydroxyacyl-CoA dehydrogenase activity in the muscle were significantly higher in response to training (P < 0.01) in both groups. However, there were no differences between the two groups concerning any of the physiological and metabolic variables measured.


CONCLUSIONS
Our results suggest that administration of vitamins C and E to individuals with no previous vitamin deficiencies has no effect on physical adaptations to strenuous endurance training.
Yfanti
Christina
C
Center of Inflammation and Metabolism at Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. christinayfanti@inflammation-metabolism.dk
Akerström
Thorbjörn
T
Nielsen
Søren
S
Nielsen
Anders R
AR
Mounier
Remi
R
Mortensen
Ole H
OH
Lykkesfeldt
Jens
J
Rose
Adam J
AJ
Fischer
Christian P
CP
Pedersen
Bente K
BK
D000222:Adaptation, Physiological / Q000187:drug effects; D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005080:Exercise Test; D005081:Exercise Therapy; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D014810:Vitamin E / Q000494:pharmacology*; D055815:Young Adult
D000975:Antioxidants; D014810:Vitamin E; D001205:Ascorbic Acid