Impact of exercise on immune cell infiltration in muscle tissue: implications for muscle repair and chronic disease.

Exercise has long been recognized for its systemic health benefits, including modulation of the immune system. Contemporary scientific inquiry has increasingly turned toward understanding the regulatory effects of exercise on immune cell dynamics within muscle tissue, highlighting their potential role in facilitating tissue repair and modulating chronic disease pathways. Following acute bouts of exercise, especially those involving eccentric or high-intensity contractions, muscle fibers experience micro-damage that triggers a well-orchestrated immune response. This phenomenon entails a coordinated, time-sensitive accumulation of immune effector cells-namely neutrophils, macrophages, and T lymphocytes-within compromised muscle tissue. Through the release of immunoregulatory and regenerative mediators like cytokines and growth factors, these cells actively participate in coordinating tissue repair by eliminating cellular debris and resolving inflammation.Macrophage polarization from a pro-inflammatory (M1) to an anti-inflammatory (M2) phenotype is particularly crucial in coordinating effective muscle repair and preventing fibrosis. However, dysregulation of this immune response, such as persistent inflammation or impaired immune cell transition, can hinder regeneration and contribute to the pathogenesis of chronic conditions like sarcopenia, insulin resistance, and muscular dystrophies. Moreover, in chronic disease states, immune cell infiltration into muscle may become maladaptive, exacerbating tissue damage and metabolic dysfunction.Regular moderate-intensity exercise appears to modulate this immune infiltration in a way that enhances repair mechanisms while reducing chronic inflammation, highlighting a potential therapeutic avenue for managing muscle-related pathologies. In-depth insight into the molecular and cellular crosstalk between physical activity and immune cell regulation in muscle tissue forms the basis for crafting specialized therapeutic strategies aimed at facilitating muscle regeneration and limiting the development of chronic pathological conditions. Through a detailed evaluation of exercise-elicited immune dynamics, this review underscores the dichotomous functions of immune cell infiltration in supporting muscle regeneration and in contributing to strategies for chronic disease prevention and management.