Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training.
Level 2 - randomized trial
Individual randomized controlled trial in humans
PubMed 25384788 · doi:10.1113/jphysiol.2014.279950
What was done
Thirty-two recreationally strength-trained men and women were randomized to receive daily vitamin C (1000 mg) plus vitamin E (235 mg) or a placebo for 10 weeks while performing heavy-load resistance exercise 4 times per week. Muscle biopsies from the vastus lateralis, 1RM, maximal isometric voluntary contraction, body composition by DXA, and muscle cross-sectional area by MRI were measured before and after the 10-week intervention. Midway through the training period, acute cellular responses (fractional synthetic rate and phosphorylation of p38 MAPK, ERK1/2, and p70S6K) were assessed via biopsies before and at 100 and 150 minutes after a standardized exercise session (4 × 8RM leg press and knee extension).
What was found
The abstract reports no numerical values. Supplementation did not affect the increase in muscle mass or acute protein fractional synthetic rate. However, antioxidant supplementation blunted the post-exercise phosphorylation of p38 MAPK, ERK1/2, and p70S6 kinase, lowered total ubiquitination levels compared to placebo, and hampered strength increases in the biceps curl.
Why it matters
This study shows that high-dose antioxidant supplementation can interfere with exercise-induced redox signaling cascades and potentially impair specific strength adaptations, challenging the assumption that antioxidant supplements aid resistance training adaptation.
Limits
The sample size is small (32 participants across both sexes). The abstract reports directional findings without numerical values, effect sizes, confidence intervals, or p-values. Only one specific high-dose regimen and a 10-week duration were tested.
Cited by
- supports High-dose combined vitamin C and vitamin E supplementation has been shown to blunt exercise-induced physiological adaptations.