Walking Question

Is it more beneficial, ie. cardio effects & burning calories, to walk 30 minutes inside a nicely air conditioned room on a treadmill or 30 minutes outside in the gosh-awful heat & humidity of Texas? This is assuming you are walking the same distance on a flat surface.

Machts nicht, as they say in Germany. Makes no difference. You might lose more water weight if you sweat more, and you will lose some electrolytes as well, but those are things you need to replace anyway. As far as calories burned, the work being done per mile is the same, so no difference in the calories burned.

However, you will probably be able to walk further in the cool insides than in the hot outsides, so longer walking means more calories burned.

Also, on a treadmill you can raise the slope and burn more calories more quickly than walking on the flat outside.

Walking is walking, so it doesn’t matter where you do it. If walking on a treadmill is more pleasant, then you are more likely to do it regularly, which is the most important thing. You might also be willing to push yourself a bit more (e.g. walk faster) if you aren’t too hot.

According to this page the body reacts more quickly to cold temperatures than warm when it comes to expending calories to maintain homeostasis. The most efficient temperatures for running times are pretty cold, anywhere from 40-60F depending on where you look. If you run in hot weather you’re more likely to get fatigued and dehydrated sooner. I’d say avoid the heat so you can exercise longer.

If the question had been: sitting around doing nothing in a cool place vs a hot place, the former would be more calorific, as your body would have to burn more energy to keep you warm.

If the question had been: running in a cool place vs a hot place, the former would be more calorific because a good runner is limited by how fast he/she can shed body heat, I gather. When it’s cool you can shed more body heat and thus run faster and burn more calories.

But the question is about walking, which generates enough heat that you don’t need to generate even more to stay warm, but not so much that your walking speed is limited by your ability to shed heat. So in this case it’s probably a wash, although you may feel a lot worse doing it in the heat and therefore do less in practice.

You do not expend more calories by running faster. In fact, because it is more efficient you expend less calories for the same distance. Running in colder temps use more calories because your body does more work to stay warm.

Obviously all of this applies if you’re doing them all for the same amount of time. Three hours of running in the heat obviously burns many more calories than ten minutes of running somewhere cool.

And burning calories to stay warm, are you kidding me? When you’re sweating like a pig already, because, you know, you are RUNNING??

You have to be careful about whether you’re talking about keeping the distance or the time constant. The OP mentioned a constant time of 30 minutes.

Actually I misspoke when I wrote that you burn less calories when you run fast because it is more efficient. You actually burn more calories for the same distance. (Obviously, for the same time you will because you are covering more distance.) Although it is more efficient, for the same distance you are doing more work because your leg movements are greater: You have a higher knee lift and a longer stride, and probably more arm movement. Most of the calories (80%) are consumed not in performing work but as heat. If it’s colder you have to use more calories to stay warm.