Changes

Exercise produces not only movement, but also heat, and this heat can be a limiting factor in performance. A number of studies have shown the cooling the body to slightly lower than normal temperatures can improve performance in both hot<ref name="PreCoolingCotter2001"/><ref name="PreCoolingKay2010"/><ref name="PreCoolingDuffield2007"/><ref name="PreCoolingBooth1997"/><ref name="PreCoolingKay1999"/> and moderate<ref name="PreCoolingLee1995"/><ref name="PreCoolingHessemer1984"/><ref name="PreCoolingSchmidt1981"/>(18,24c) conditions. This pre-calling does not appear to change [[Muscle|muscle ]] metabolism, so it is probably just offsetting the natural rise in temperature<ref name="PreCoolingBooth"/>. Pre-cooling does not appear to help with Sprint performance<ref name="PreCoolingDuffield2007"/><ref name="PreCoolingSleivert2000"/><ref name="PreCoolingDuffield2003"/>, and the benefits may be limited to 30-40 minutes of endurance exercise<ref name="PreCoolingNarubi2001"/>. There is some evidence that pre-cooling the working muscles and torso could impair performance compared with pre-cooling just the torso<ref name="PreCoolingSleivert2000"/>.