Running in the Heat: Adapting Heat Training for Younger Runners

As we start getting into what have always been called the “dog days” of Summer, we have longer and often oppressively hot days. It’s something we will adjust to, either with changing start times, bringing extra fluids, or, for the morale booster, with me bringing the spray mister.

How concerned should we be with children running in the heat?

I think it’s useful to look at heat as a part of the General Adaptation Syndrome model that is the basis for most athletic training. The idea is intuitive and simple, and we see and experience it all the time.

When your body is exposed to some form of external stimulus that it is not used to, it creates a stress response that your body, over time, will adapt to.  For example, if you’ve never lifted a weight before and do some biceps curls with a dumbbell, your arms will be sore in about one or two days afterwards. Your arm is not adapted to that type of external loading. You’ve now damaged the muscle fibers.

But a strange phenomenon also happens. If you keep doing curls, eventually your biceps get over that soreness. If you’re consistent with the dumbbell curls, those biceps muscles might even get bigger. They’ve now become more adapted to the external strain you’ve applied to them. The human body is a wonderfully adaptive thing, constantly establishing a certain equilibrium with its external environment.

We apply the same principles to our running. We apply running strain, either through duration, frequency and/or intensity, and through the magic of the stress adaptation model, our cardiovascular system becomes more adapted to that external stimuli. In other words, we get faster. We can run farther.

We can think of heat as another external stimuli that applies physical stress and strain, and, as such, it’s something we can adapt to. In some ways, it’s a little like training at altitude. It’s an additional factor that applies stress/strain, and there was a study that measured the effects of heat training and found that heat adaptations had benefits to performance even at cooler temperatures, most likely because it stimulates an increase in total plasma volume.

But - and there’s always this important caveat - we’re also working with young people who are still growing and still developing, and the physical act of growing itself is its own type of stress and strain. We need to account for that.

It’s important, at least in my opinion, to give younger athletes sufficient doses of stress/strain without putting them through the wringer. Overtraining is a problem with younger athletes, and there is a smaller margin or error in finding that optimal balance point between strain and successful adaptation.

So … running in the heat is probably ok in our circumstances, and it’s good to expose our young runners to some heat, but it’s also smart to err on the side of caution at times and dial it back. They can’t do what adults can do.

Some simple things to consider when running in the heat:

• Drink a little more than what your thirst tells you. That thirst response is a little slow to adapt to heat. We often don’t drink enough when it gets hotter.

• Adjust the pace. Go a little slower in the heat and try to go with reverse splits - starting slower and ending faster

• Check the toilet afterwards. Is your pee a little darker than usual? You’re dehydrated. Drink more.

• Change around run times. Going earlier in the morning or later in the evening, aside from avoiding the hottest part of the day, is a bit of a morale boost. It’s something different.

• Consider electrolyte replacements on longer runs. There are plenty out there, and you just need something with some sodium, magnesium and potassium.