Exercising at higher temperatures

Question

Aside from the obvious safety concerns of heat exhaustion, heat stroke, heat prostration, etc., what is known about the detriments or benefits of exercising at higher-than-comfortable temperature/humidity?

To put it concretely, the gym I currently use has a room temperature these days of perhaps 75 F, with fairly muggy humidity. I find that much higher than I'd prefer to exercise in, particularly for running on a treadmill (at a 7:30--8:30/min pace). I would ideally enjoy 66 F with low humidity, At the current temperature/humidity I sweat profusely and have been backing off of my previous exertion on the treadmill out of basic caution, though it strongly feels I could continue at a higher exertion without any risk of serious harm. (I am well hydrated and have never felt close to dizzy or anything like that--just tired. And hot.) But I am concerned about less obvious harm...

And so, what I want to know is: is there evidence to show that sustained hard exercise at higher temperatures/humidity has any subtler systemic harm (that is, subtler than the obvious ones listed above)? I mean, is it "bad for your brain" Or other organs? Does it put too much stress on your system?

Or is training in conditions in which sweating is profuse and sustained actually good training in some sense? Such as training your system to be more efficient or other benefits?

Answer 1

People have been doing physical exertion for millenia without air conditioning. This includes training in the cold as well. Each extreme has its own challenges, there won't be any lasting systemic damage if you take care of the issues.

Training in Heat

• Hydration is most important. You will sweat more--and sweating is a good thing.
• Your performance will be diminished. It takes time to get adapted to higher heat, so don't push yourself too hard too fast.
• If you stop sweating, or start feeling dizzy--stop exercising, cool and rehydrate yourself. Something not normal is happening, and you'll probably need medical attention (due to the issues you listed in the opening statement).

Training in Cold

• You will sweat, so keep downtime to a minimum.
• Metal will be really cold to the touch, so if you lift weights you'll have to be mentally prepared for an ice cold bar.
• In more extreme cold temperatures, you'll probably need a space heater to keep the bar from freezing your hand to the bar with your sweat.
• Hydration is still an issue--you get dehydrated quicker the further from room temperature (goes for heat and cold)
• Same warning as for heat about stopping sweating, feeling dizzy, and acclimating yourself.

Bottom line is that you will need to adapt yourself to training in that environment. Since we aren't talking about the extremes that you would find even in a garage (90 degrees F in the summer, 10 degrees F in the winter), the only real concern is hydration.

Answer 2

I am from cold New Zealand and was posted to 34 degrees C (93.2F) in Timor Leste. I found that I adapted quickly, drank lots, and made incredible gains in strength and lost fat rapidly due to the heat and ease at which my muscles warmed up. So harden up, push through, watch your hydration and enjoy the gains.