Hot enough for ya?

Its hot.

Damn hot.

And humid. Actually, humid isn't a strong enough word – it's just plain wet. You know what your bathroom feels like after a long, hot shower, when you can't see anything through the thick fog hanging in the air? That's what it feels like when I walk out my front door.

Then the wind starts whipping around and it feels like I live in a convection oven.

Its so oppressive it's actually sapping my will to live – and my desire to even think about exercising. All I want to do is turn on every fan in my house, turn the AC down to "meat locker" and curl up in the fetal position in a bathtub full of ice until November.

Not surprisingly, my outdoor workouts are suffering in both frequency and intensity. Which has led me to wonder two things:

1) Does working out in the heat burn more calories than in cooler temperatures?

and

2) At what point is it "too dangerous" to vigorously exercise outdoors

To find answers I tracked down an old Q&A with Mr. Cardio himself, Dr. Kenneth Cooper, who just so happens to live in the same stifling soup I do.

As for question #1: Yes, working out in extreme heat requires an additional expenditure of energy. I figured as much, since doing the same workout today feels much harder to trudge through than it did a few months ago.

Exposure to extreme heat accelerates your heart rate. Obviously, so does exercising. This creates a "synergistic" effect, or as Dr. Cooper explains, "one plus one equals three." So compared to working out in January, I'm burning more calories in the same amount of time in July. However, I'm also placing more of a strain on the ticker.

Which leads to question #2: At what point does that strain become dangerous? Well, obviously if you're 97 years old with a history of heart disease, going for a 15 mile run at 3pm in August in Texas might not be the best of ideas. But what about for a relatively healthy fat man in his mid-thirties?

Dr. Cooper claims that acclimatization is the key. If you begin to sweat soon after starting exercising (or in my case, soon after you start thinking about exercising), your body is well acclimated to the heat. Actually, the sooner you start to sweat, the less likely you are to suffer a heat related illness. So I can safely say I'm well-acclimated, but that doesn't mean there's no risk at all.

When Dr. Cooper was in charge of Air Force training in San Antonio, several recruits from the north died in the heat. He started a monitoring program and found rectal temperatures of those not acclimated reached as high as 106 degrees after just a two mile run (remind me never to participate in a heat exercise study). He then developed a system based on the heat and humidity to gauge the risk of heat related illnesses.

His basic guideline is this: if the combination of temperature and humidity exceeds 150, you should avoid vigorous exercise outdoors.

Living in a part of the country where the four seasons are Almost Summer, Summer, Still Summer, and Christmas, this information is a little unsettling. For instance, at 8am this morning the temperature was 83 degrees and the humidity was 68%. That's already over the limit!?!

And although I'd like to to use this information to justify shelving my workouts for the next couple of months, the last thing I want to do is break this habit. So... along with making sure I'm drinking a ridiculous amount of water, I've made a few modifications to my routine: 1) I'm going later in the day - around 5:30 instead of 3:30. While its not any cooler temperature wise, the sun is much less intense and there's a lot more shade on the trail. 2) I've made my route a little shorter. I've cut a mile off my bike ride and about a half mile from my walk/jog. And 3) I'm easing up on the intensity. Walking more than jogging and dropping a gear or two on the bike. Maybe that washes out any additional heat calories I'm burning, but at this point of the year, my main goal is just to stay alive until the blessed cool winds of Christmas blow into town.