Summer in The South, especially this summer, is a killer for temperature and humidity which puts big stress on the body when outside training. People in endurance sports like the idea that more suffering when training means a better race, and what better time to suffer than in the heat because THE RACE WILL BE HELD IN THE HEAT! Right? Well, kind of….
I’m an Old School guy with a kind of ‘common sense’ approach to training for triathlons; mostly from my own experience, plus heavy input from the best minds in the business, including that of my own coach.
It takes a balance of the two…..run in the heat to get used to it; and to get faster, run on a treadmill with a 0.5 – 1% slope. Speed increases come from those sessions you REALLY don’t like: normal running speeds punctuated with insanely high speed blasts with rests, repeated until you just don’t want to do anything for a while; or a ‘ladder’ of some sort, where you start at a decent heart rate and end up pushing into an anerobic zone in the later part of the run. BTW, you don’t want to do more than one of those a week; maybe two if you’re an elite or super experienced. …and another BTW, ….you’ll only experience the gain if you allow for the proper rest period that your coach recommends.
The problem with doing those intense sessions outdoors when it’s really hot (use really early morning if it helps) and humid is that the stress is so high that you can’t properly do the session and you won’t get the speed results as if you had done that in a more controlled environment. If you DO a session like that in the heat you will require a much longer recovery period and I think it significantly reduces the overall gain you could have had. I don’t enjoy a treadmill as much as outdoors and have tried everything to make it more interesting: from playing my best music, using the TV tuner built into the workout room; do whatever works for you.
Now, back to getting used to the heat. You’ll notice that the next assigned run wouldn’t be one of those intense things; it’ll be a longer ‘endurance’ run or an easier brick run; something that you can do in the heat without blowing up.
So you DO need to get used to running in the heat, but you don’t need to pile on the pressure of a speed-power session at the same time. Save those workouts for the treadmill so you CAN get faster; or if you can get out really early, it might be cooler.