The adaptability of the human body to environmental conditions is astonishing to me. As runners, we experience this as a year-round phenomenon, running in all sorts of weather that appears to others to be extreme, but is actually quite tolerable because we’re constantly adapting to the changing conditions. Lately, the weather in New England has taken a turn towards the hot and the sticky, with steamy days and nights that make you feel like a limp rag. But no matter how hostile the humidity, there’s no question that at the end of the day we’ll ignore skeptical looks and cautionary comments from non-runners and we’ll set out through the haze to get in our daily miles.

Personally, I find an odd satisfaction in running when it’s really hot and humid. Maybe it’s because everything feels looser, or maybe it’s just that the run slows down so that there’s less wear and tear. I also notice that no matter how slowly I run, if the weather’s really oppressive, I seem to stay very focused, monitoring vital signs to make sure that nothing is amiss. Racing in the extreme heat would be another matter entirely, but just running in those conditions is actually quite satisfying. If the amount of sweating is a good measure of effort, even a short run feels like a good effort.

I guess you have to like sweating to like the humidity. Sweat evaporation is one of the major ways the body has to cool itself, and “improved” sweating (i.e., changes to sweat content and volume) are one of the body’s adaptations to hot weather. The problem is, of course, that when it’s really humid, sweat doesn’t evaporate, but drips from the skin in useless drops. It’s noticeable during runs, but when you really pay attention is after you finish and a surprisingly large pool of sweat forms at your feet.

The other think I like about this weather is that the same principle of adaptation that allows one to run at all when it’s hot and humid, functions kind of like altitude training in that it can improve performance when you return to a “normal” environment. Run for a week or two when the air is like warm soup and when cool, dry weather returns, you’ll feel like you can fly. On the other hand, for anyone doing elite workouts, the crappy humidity makes it pretty tough to get in the kind of quality you need to be sharp, so maybe “humidity training” is only valuable if you’re in a base phase or if you’re specifically preparing to compete in similarly tropical conditions.

(A quick digression: in altitude training, there’s the concept of “train low, sleep high,” meaning that you train at low altitude where it’s possible to run faster, and then sleep in real or simulated high altitude so that your body will adapt to lower levels of oxygen in the blood. From the very little reading I’ve done into heat adaptation, there appears to be an opposite protocol used where you “train hot, sleep cool.” That is, you train in the heat and humidity, but rest in cool temperatures to aid recovery. It actually makes more sense to me than the altitude training protocol, since it seems that you want to apply maximum stress during the target activity, but not during rest.)

I wondered what this year’s Olympic distance runners were doing to prepare for running in Rio, since I assume it will be fairly hot and humid there. Of course, Rio de Janeiro is in the Southern Hemisphere, so August is late winter, and according to holiday-weather.com:

“[In Rio] The overall average temperature in August is 22°C [~72 deg F]… In terms of rainfall, August is the driest month of the entire year. The total amount of precipitation is no more than 51mm (~2″)…”

So I suppose it depends on the day, and that marathoners and other endurance athletes might catch a break and get warm and dry instead of hot and humid.

Anyway, back here in New England, where very few of us are preparing for the Olympics, we’ll just have to sweat our way through a few more sticky runs, taking the proper precautions of course, and then hide out in air-conditioned office building or movie theaters when we’re not running. Soon enough the weather will change again, and we’ll be adapting to something new. The important thing is just to keep moving, keep adapting, and accept whatever the season has in store for us. It’s hard to believe, but it was only five months ago that we were running around Fresh Pond with the temperature at -6 F.

Although it seems unthinkable now, shivers are right around the corner.