Effects of NAC Supplementation on Skeletal Muscle Performance Following Aseptic Injury Induced by Exercise
Effects of NAC Supplementation on Skeletal Muscle Performance Following Aseptic Injury Induced by Exercise
In this investigation the investigators utilized NAC administration to foster GSH availability during an 8-day period following eccentric exercise-induced muscle damage in order to test our hypotheses: i) antioxidant supplementation does not disturb performance and adaptations induced by exercise-induced muscle injury and ii) redox status perturbations in skeletal muscle are pivotal for the regulation of muscle' inflammatory response and repair.
The major thiol-disulfide couple of reduced (GSH) and oxidized glutathione (GSSG) is a key-regulator of major transcriptional pathways regulating aseptic inflammation and recovery of skeletal muscle following aseptic injury. Antioxidant supplementation may hamper exercise-induced cellular adaptations.
Our objective was to examine how thiol-based antioxidant supplementation affects skeletal muscle's performance and redox-sensitive signalling during the inflammatory and repair phases associated with exercise-induced micro-trauma.In a double-blind, counterbalanced design, 12 men received placebo (PLA) or N-acetylcysteine (NAC, 20 mg/kg/day) following muscle-damaging exercise (300 eccentric contractions). In each trial, muscle performance was measured at baseline, post-exercise, 2h post-exercise and daily for 8 consecutive days. Muscle biopsies from vastus lateralis and blood samples were collected pre-exercise and 2h, 2d, and 8d post-exercise.
Inclusion Criteria:
a) recreationally trained as evidenced by their maximal oxygen consumption levels (VO2max >45 ml/kg/min), b) were engaged in systematic exercise at least three times/week for ≥12 months), c) non-smokers, d) abstained from any vigorous physical activity during the study, e)abstained from consumption of caffeine, alcohol, performance-enhancing or antioxidant supplements, and medications during the study.
Exclusion Criteria:
a) a known NAC intolerance or allergy, b) a recent febrile illness, c) history of muscle lesion, d) lower limb trauma