Two beliefs about soreness are widespread among men who train, and both are wrong: that soreness proves the session worked, and that it should be eliminated as fast as possible.
During exercise, the burn comes from metabolic byproducts — hydrogen ions and inorganic phosphate — altering the local chemical environment and stimulating nerve endings. It clears within minutes. Lactic acid takes the blame unfairly: flat running produces high lactate and no delayed soreness, while downhill running produces almost none yet causes significant DOMS days later.
