Despite the beneficial effects of regular physical activity, prolonged high intensity exercise could negatively affect muscle performance. Muscular contraction generates free radicals that accumulate in several tissues, including blood and skeletal muscle. In particular, reactive oxygen species (ROS) have been associated with molecular oxidative damage, such as an increase in protein oxidation and lipid peroxidation, and are key to the early perception of fatigue during training.

Strenuous physical exercise has also been shown to be related to the alteration of gut microbiota, which plays a fundamental role in modulating muscle adaptation to extensive training. In recent years, the existence of a “gut-muscle axis” has been hypothesized, which regulates muscle proteins and function and is involved in the pathogenesis of some muscular disorders. In this sense, a balanced intestinal microbiota produces a variety of biologically active metabolites which play an important role in reducing inflammation and ROS production and attenuating damage to myocytes.

The aim of this Special Issue is to collect original research and review articles that shed light on the physiological, metabolic, and cellular mechanisms that regulate the interaction between gut and skeletal muscle, with a particular interest in elucidating those processes that reduce oxidative stress and improve muscle performance and adaptation to extensive training.

Potential topics include but are not limited to the following:

• Generation of contraction-induced free radicals
• Vigorous exercise and disruption of intestinal microbiota
• Mutual relationship between gut and skeletal muscles
• Positive effects of intestinal bacteria on reducing ROS muscle production
• Association between redox balance and muscle performance
• Possible use of probiotic supplementation to improve adaptation to exercise