Changes

It is generally accepted that exercise at a constant effort will be voluntarily terminated once the core body temperature reaches about 40c/104f<ref name="Tucker-2008"/>. However, if subjects are allowed to vary their pace freely, they will preemptively reduce their exercise intensity to prevent their core temperature form reaching the critical point<ref name="Tucker-2008"/>. One mechanism for this reduction is that fewer [[Muscle|muscle fibers ]] are recruited in hot conditions, even before the core body temperature starts to rise<ref name="Tucker-2004"/>. Elevated core temperature reduces the voluntary maximum force generated, though it is unimpaired when electrical stimulation is used, indicating the central nervous system is responsible<ref name="Nybo-2008"/> . When exercising at a constant [[Rating of Perceived Exertion]], subjects steadily reduced their power output at 59f/15c, 77f/25c or 95f/35c even though their perception of their temperature comfort remained constant<ref name="Tucker2006"/>.