How much power do you lose in extreme heat? How about extreme heat + aero position?

I don’t have much power data on the bike to compare with since I only started riding with a power meter in October and it hasn’t been really hot here in Belgium yet. But it hits my run hard when it’s hot… 15-20"/km slower for the same heart rate even on a long run.

Training here in Arkansas, where it can get up to 100 F in the summertime with (literal) swamp-like humidity, heat index > 110 routinely. Heat can end a workout, no matter how focused or experienced a rider. There seems to be a HEAT OVERRIDE button somewhere in the brain that gets pushed, and the effort just shuts down independent of hydration, diet, gear, etc. This coming from someone who grew up here and has played outdoor sports forever, long history of athletic training in the heat. If the heat index is serious, it is mandatory that structure be moved indoors.

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I’m in the same boat: I’ve lost 10% off my FTP since the southwest desert heat wave (season) arrived last week. I did a ramp test this morning to validate the drop.

Q: do I train at new/lower FTP or do I stay the course with higher FTP (drop intensity 10%) with the expectation that my body will adapt in the next few weeks? (Summer is just starting in Mojave Desert). OR: is this essentially the same thing that I am asking? (face palm)


I seem to lose a lot in the heat and its not even that extreme (its the UK FFS). On Thursday night I was sitting comfortably at 253w in 15 deg, roll on to today I was struggling at 201w. Probably was exasperated by me burning too many matches though :neutral_face:

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I’m in central Texas where Summer is the season you put your bike on the trainer :laughing:
The heat messes me up. The sun here just seems to beat you down even if ambient temp is only in the 80s. The days that it’s 100+ I struggle to even get above 90%FTP on a TT-like ride for any meaningful amount of time. For my 6hr races I usually come out with average power about 10-20W lower than I would have expected given my power curve/FTP/pacing strategy. It’s usually core temp, not legs, that take me down in any race that’s between May and September.

How long was your TT?

I hate the heat from a comfort standpoint but it doesn’t affect my power much, if at all, as long as I’m able to stay hydrated.