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Intramuscular adaptations to eccentric exercise and antioxidant supplementation
Chad M Kerksick1, Richard B Kreider, Darryn S Willoughby
1Health and Exercise Science Department, University of Oklahoma, 1401 Asp Avenue, Norman, OK 73019, USA.
Amino Acids
|December 8, 2009
Summary
Prophylactic supplementation with N-acetyl-cysteine (NAC) and epigallocatechin gallate (EGCG) blunted muscle soreness after eccentric exercise. While both supplements reduced soreness, further research is needed on their impact on apoptosis and oxidative stress.
Area of Science:
- Exercise Physiology
- Nutritional Biochemistry
- Cellular Biology
Background:
- Eccentric muscle contractions induce muscle damage, inflammation, and apoptosis.
- N-acetyl-cysteine (NAC) and epigallocatechin gallate (EGCG) are antioxidants with potential muscle-protective properties.
- Understanding the prophylactic effects of NAC and EGCG on exercise-induced physiological and cellular changes is crucial.
Purpose of the Study:
- To investigate the effects of prophylactic NAC and EGCG supplementation on skeletal muscle changes following eccentric exercise.
- To assess the impact of these supplements on muscle strength, soreness, inflammation markers, and apoptosis.
- To compare the effects of NAC and EGCG with a placebo (glucomannan).
Main Methods:
- Thirty healthy males participated in a double-blind, placebo-controlled study.
- Participants were supplemented with NAC, EGCG, or placebo for 14 days prior to eccentric knee extensor exercise.
- Muscle strength, soreness, blood markers (LDH, CK, cortisol, neutrophils, lymphocytes), and muscle apoptosis markers were assessed at multiple time points post-exercise.
Main Results:
- All groups showed reduced peak torque and increased soreness and muscle damage markers (LDH, CK) post-exercise.
- NAC and EGCG groups reported less soreness at 24 hours compared to placebo.
- While apoptosis markers (bax, bcl-2) increased in all groups, no significant differences were found between groups for most apoptosis markers, except for caspase-3 activity which was elevated at 48h.
- Inflammation markers (neutrophil:lymphocyte ratio) showed transient changes, with EGCG showing a trend towards lower values than placebo at 48h.
Conclusions:
- Eccentric exercise significantly increases muscle damage, apoptosis, and inflammation.
- Prophylactic NAC and EGCG supplementation may attenuate muscle soreness post-exercise.
- Further research is warranted to elucidate the specific mechanisms of NAC and EGCG in mitigating exercise-induced cellular stress and apoptosis.
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