Effects of Protein and NAC Co-ingestion on Skeletal Muscle Recovery
Trial Parameters
Brief Summary
Previous evidence suggests that though N-acetylcysteine (NAC) supplementation following eccentric exercise-induced muscle damage disrupts the skeletal muscle's repair and remodelling process at 8 days of recovery, it attenuates substantially the decline of skeletal muscle performance during the first 48 hours of recovery. The enhanced performance capacity during the first phase of recovery in response to NAC supplementation might be attributed to the altered redox status in skeletal muscle as a consequence of the NAC-mediated elevation of reduced glutathione (GSH) levels. The rise in GSH results in a redox-dependent attenuation of immune cell mobilisation and reduction of oxidative stress response, leading to a blunted rise of muscle damage and inflammatory markers during the first 2-3 days of recovery. However, following exercise-induced muscle damage, protein synthesis increases in skeletal muscle over the next 24-48 hours to support its repair process, and thus protein supplementation might accelerate the recovery process by enhancing the protein synthetic response. Therefore, the present study aims at investigating for first time the combined effect of NAC and whey protein supplementation on the short-term (during the first 72 hours) recovery process of skeletal muscle following damaging exercise (eccentric exercise) and compared it with the well-documented efficacy of NAC supplementation. The results of this study might be particularly useful for athletes, such as those in soccer and basketball, that participate in 3 games or intense training sessions during the same macrocycle with only 48-72 hours of recovery in-between.
Eligibility Criteria
Inclusion Criteria: * Free of asthma, kidney disease, bleeding disorders, peptic ulcers. * Free of musculoskeletal injuries and limitations. * Abstain from dietary energy restriction. * Do not use medication such as anti-inflammatory drugs, antibiotics, antihypertensive drugs or anticoagulants. * Do not use dietary supplements such as protein, carbohydrate, antioxidants, vitamins etc. * Free of N-acetylcysteine intolerance. * Non-smokers. * Abstain from alcohol throughout the study. Exclusion Criteria: * Presence of asthma, kidney disease, bleeding disorders, peptic ulcers. * Musculoskeletal injuries and limitations. * Dietary energy restriction. * Use of anti-inflammatory drugs, antibiotics, antihypertensive drugs or anticoagulants. * Use of dietary supplements such as protein, carbohydrate, antioxidants, vitamins etc. * N-acetylcysteine intolerance. * Smoking. * Alcohol consumption during the study.