Cooler environments allow for steady state exercise output and heart rate, while warmer environments cause earlier cessation of exercise.

“So some people are running in a nice chilly laboratory, they get their heart rate up. So maybe their heart rate goes from, you know, 40 or 50 baseline heart rate, maybe it gets up to 80 or a hundred and then they keep the rate of the treadmill going the same and they'll just plateau. So they're getting into a steady state cadence or rhythm and their heart is beating it more or less a steady state. Eventually they'll probably stop 'cause they have something else to do but people will continue at that temperature and at that heart rate, unless you start turning up the temperature in the room and at some point they will stop and they'll stop much earlier when it gets hot because of something called cardiac drift, okay?”