Final answer:
DOMS is characterized by delayed muscle pain post-exercise and was historically attributed to lactic acid buildup, which is now considered unlikely. Current understanding is that DOMS results from microtears in muscle fibers, not the presence of substances like hydroxyproline.
Step-by-step explanation:
Delayed onset muscle soreness (DOMS) is commonly experienced after intense physical activity, specifically when the muscles are subjected to unfamiliar levels of exertion. Historically, the accumulation of lactic acid was believed to be the cause of the stiffness and soreness that defines DOMS.
Lactic acid is produced during anaerobic respiration when the body's oxygen demand exceeds the oxygen supply. However, this lactic acid quickly disperses from the muscle tissues and is unlikely to be the primary cause of pain that lasts for several days post-exercise.
Currently, research suggests that DOMS is more likely due to microtrauma leading to tiny tears in the muscle fibers. This damage is a result of exertion past the usual load the muscles handle, leading to inflammation and soreness as part of the body's natural repair process. The role of substances like hydroxyproline, a major component of the protein collagen, is not cited as a causative factor in DOMS.