Intense physical activity in a non-air-conditioned environment can significantly raise core body temperature prior to hyperthermia treatment.

“they told me I needed to warm up prior and again this is during the heat wave so I went for a walk outside for about 20 minutes and I'm already sweating then I came in and they put me on a bicycle like a stationary bicycle in non-air-conditioned little gym they have there and I rode my ass off for a half hour so I'm already dripping with sweat”