Fig. 5.

Aging process is associated with increased reactive oxygen species (ROS) and inflammation resulting in muscle dysfunction. Decreased levels of insulin-like growth factor (IGF-1) are related to aging with the subsequent diminished protein synthesis and muscle growth via phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway. Exercise may exert potent anti-inflammatory and anti-oxidative stress (i.e., through nuclear erythroid-2 like factor-2 (Nrf-2) activation) effects and consequently improve muscle function. In addition, exercise increases protein synthesis via activation of IGF-1 pathway and target myokines reducing protein degradation. An increased signaling of the transcription factor peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) is also induced by exercise, improving mitochondrial function and reducing inflammation mediated by nuclear factor κB (NF-κB).