Abstract
This systematic review examined the effects of whole protein and commonly consumed amino acid supplements on markers of exercise-induced inflammation and oxidative stress and was reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched from inception until June 2021. The inclusion criteria were randomized clinical trials in humans, healthy adult participants (≥18 years), dietary protein/amino acid interventions, and measurements of oxidative stress/the redox status or inflammation post-exercise. The Cochrane Collaboration risk of bias 2 tool was used to critically appraise the studies. Data extracted from thirty-four studies were included in the systematic review (totaling 757 participants with only 10 females; age range 19–40 years). The included trials examined five types of whole protein and seven different amino acids supplements; most studies (n = 20) failed to identify statistically significant effects on markers of inflammation or oxidative stress after exercise; some (n = 14) showed either anti-inflammatory or antioxidant effects on some, but not all, markers. In conclusion, we found weak and inconsistent evidence that dietary protein/amino acid interventions can modify exercise-induced changes in oxidative stress and inflammation. However, given that these were not the primary outcomes in many of the included studies and many had design limitations, further research is warranted (Open Science Framework registration number: 10.17605/OSF.IO/AGUR2).
Highlights
Publisher’s Note: MDPI stays neutralHigh-intensity, unaccustomed, or prolonged exercise imposes a high physiological demand that perturbs homeostasis and may result in skeletal muscle damage [1]
Dietary protein interventions have been suggested to modify inflammation and redox status and may support recovery from high-intensity and/or muscle damaging exercise or help to manage low-grade chronic inflammation associated with aging and noncommunicable diseases. This is the first systematic review evaluating the effects of various whole protein and amino acid supplements and foods on exercise-induced inflammation and oxidative stress in humans
This study clearly showed that dietary protein and leucine dose-dependently influenced immune-related repair mechanisms post-exercise, leading the authors to conclude that the immune-driven events likely complement muscle protein turnover and remodeling
Summary
Publisher’s Note: MDPI stays neutralHigh-intensity, unaccustomed, or prolonged exercise imposes a high physiological demand that perturbs homeostasis and may result in skeletal muscle damage [1]. The precise mechanisms of exercise-induced muscle damage (EIMD) are yet to be established, but it likely stems from a combination of mechanical and metabolic stress [2,3]. EIMD is associated with an acute inflammatory response, characterized by increases in circulatory and intramuscular inflammatory markers such as C-reactive protein (CRP), cytokines (tumor necrosis factor (TNF-α) and interleukin-6 (IL-6)), and transcription factor nuclear factor kappa beta (NF-κB) [5,6,7]. Exercise increases the production of reactive oxygen (ROS) or reactive nitrogen (RNS) species [8,9], which partly stem from immune cells such as neutrophils [10]. Muscle damage is not necessary for an inflammatory response after exercise; inflammation and increased generation of ROS/RNS with regard to jurisdictional claims in published maps and institutional affiliations
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