Same here, I did surprisingly OK in Southern California dry heat but can struggle in north Texas, which isn’t as bad as other places but still very different to that desert heat.
I need to start doing some easy un-fanned trainer rides so I don’t get mad headaches on these increasingly hot and increasingly faster Saturday morning drop rides. It’s a hard balance.
Edit / Typo that bothered me (dessert > desert)
Make sure you’re getting enough electrolytes in your bottle. I’ve made an effort this spring to be more consistent using, and increased the amount of, sodium in my bottles, and it has made a huge difference in how I feel when I get off the bike and more importantly how I feel that evening and the next day. I still sweat like crazy on the bike.
Also, as to heat adaptation, I say embrace it and get it done, especially if you live in those environments (I’m in FL). I learned a few years ago, that getting out there and getting adapted to the heat over a couple weeks time pays dividends for the rest of the summer, on and off the bike. If yo do it, you won’t have the same dread about the heat on your Sat morning ride, you’ll be more comfortable inside on the trainer, and you won’t be (as) miserable doing other outside activities. I noticed the last couple days that I’ve been feeling cold in the house (a/c set at 74) so I bumped it up to 76 yesterday, and was perfectly comfortable, even sleeping last night).
And be careful with Oreo Cookie’s cold water prescription. If you get into heat trouble, dumping ice water into your stomach can backfire on you. I’ll add some ice to my 2nd bottle so it’s (only) cool and refreshing in that 2nd hour. Also, I’ve tried freezing water in insulated bottles and froze too big a chunk and it wouldn’t thaw fast enough to keep up with my needs when the time came.
If you are riding the same route at the same speed let’s say Z2. Is the muscle adaptation any different at temperature of 25C than 40C?
Or another way to look at it ; if on the trainer and I heat up the room to 40C will it affect the muscle adaptation?
Haven’t read anything about improved “muscular adaptions” (aka. peripheral adaptions) due to heat training.
The only improved adaptions I have heard about in this regard are central adaptions like increased blood volume (a bit like altitude training) and of course improved tolerance to physical activity in heat.
Peripheral (leg muscle) adaptations too.
Nice pic from a summary article:
Article:
I’ve got more, randomly pulled that one up. Mixed data on performance in reduced temperatures, but at least one study and my n=1 support improved performance in lower temperatures.
I lived in NM for a couple of years and would regularly ride in the middle of the day at 100F. Because it was dry, I didn’t even sweat that much compared to a humid environment.
Others in my club would ride at 6/7am and were always avoiding the heat like the plague.
But once you get used 100F, 85F feels like a cool breezy day.
It’s still aerobic training if you stay well below threshold. Targeting zone 2 is fine but I wouldn’t worry about normal drift. To me the solution is not to use watts and the higher heart rate but to just go a bit slower. If it’s super hilly in your area, get an easier gear on your bike so you can stay aerobic and not go above threshold when you don’t want to.
I live in central TX and I do a good bit of riding/training in the heat. Heat acclimation helps, but at some point you get into a math problem where you are producing more heat than your cooling system can dissipate. At some point, the body is smart enough to shut down (hopefully before things go totally sideways). It’s like a truck climbing a mountain pass. Your radiator might have enough capacity to keep up or you may have to back off the power to reach equilibrium. When riding, that may be in Z2, might be tempo, might be threshold. So many factors besides temp and power, including speed through the air, humidity, radiant heat from direct sun, etc. The best you can do is adapt the best you can and then listen to your body. Watching HR doesn’t work for me personally, it’s always off the charts with heat and/or caffeine. An effective management tactic I’ll use when racing is to make hay while it’s still early/cool when I know it’s going to be a hot day. I find that regardless of how many matches I’ve burned early, the heat will become the limiter as the day progresses. So, use those watts while you can.
Muscle adaptations, probably not. But the heat is another stress that will add to your fatigue. Heat adaptations also has it’s own benefits like increased plasma volume. So it probably won’t be a multiplier to your normal gains but it has it’s own pros/cons you need to balance with the rest of your training.
muscle adaptations include reduced oxygen consumption and glycogen sparing.
So no need to move the trainer indoors this week when the garage gets above 95F
Thanks
the paper I provided above (Zone 2 and heat - #25 by WindWarrior) has a list of protocols, for example self-paced:
or constant workload
For myself, I don’t worry, just go out and ride by perceived exertion. In the Saturday workout I posted above (Zone 2 and heat - #14 by WindWarrior) you can see as the temperature drops I increase power while still keeping HR well below normal for such a ride.
My garage hits 90+F and I’ve used the trainer with 2 fans and 3 fans. I’ll modify workouts if necessary. Last week I did some 30-sec jobbers outside in the heat, followed by a shorter threshold interval - that was a ‘heat friendly’ workout format. These days I just go outside and ride, however where I live outside is time-efficient, and better cooling.
I think some of the responses here have made this seem really complicated.
Yes, your HR will be higher, no, it’s not a problem.
Ride easier, drink more water and take breaks in the shade.
Lots of good info!
Heat, as well as many other outside factors such as humidity, fatigue and even caffeine, can definitely affect heart rate, making it harder to keep your heart rate in a specific HR zone and even change from day to day. This is why at TR we are firm believers that power is the ultimate metric if you are doing interval-based training. 
In short, if you’re out of zone on a hot day, you’re still out of zone. So, it’s important to really listen to your body and adjust your effort accordingly, especially when training in hot conditions. You may need to lower your intensity to stay within your target heart rate zone.
