Muscle tissue damage can occur in all three types of muscle tissue: skeletal, cardiac, and smooth muscle. Skeletal muscle tissue is susceptible to damage from strenuous exercise. In particular, eccentric exercises (muscle lengthening) cause fatigue more rapidly than concentric exercises (muscle shortening), leading to muscle damage. Indicators of muscle damage include loss of strength and range of motion, accumulation of cellular calcium, delayed onset muscle soreness (DOMS), and increased blood levels of creatine kinase.

Almost immediately following damage to muscle, neutrophils travel to the injured area via the bloodstream, initiating the immune response. Neutrophils release free radicals and other toxins that help remove dead muscle fibers. Following the neutrophils, monocytes migrate to the area and differentiate into macrophages. These cells are responsible for phagocytosis of the tissue debris. Additionally, macrophages are responsible for activating the satellite cells essential...