The document discusses delayed onset muscle soreness (DOMS), which causes muscle pain and discomfort in the 24-72 hours after exercise. While the exact physiological mechanism is unknown, it is likely due to mechanical damage to muscle cells during exercise. DOMS is commonly experienced by athletes and is used experimentally to study myogenic pain. Various strategies like massage, stretching, anti-inflammatories, and cryotherapy have been used to treat DOMS, but results have been mixed with minimal pain relief and inconsistent effects on strength and injury markers.