Biochemically, lactic acid build-up will cause fatigue in the muscles, and unless a proper rest period for its removal is provided, the participant will fatigue prematurely. Without such a proper rest period, the acid cannot be used as an oxidative fuel and may result in either a less-than-optimal workout (in the best-case scenario) or a potential cardiovascular or musculoskeletal incident (in the worst-case scenario). Such fatigue can lead to a breakdown in form and, therefore, potential musculoskeletal damage due to hyperextensions or the lack of ability of the antagonist muscles to decelerate the movement and thereby prevent mechanical injury.