Running/Jogging

joeboo_sl said:

I've always been curious about this, but never really looked into it...

If you're working out and doing some sort of cardio (running, stairs, bike, whatever), do you actually burn significantly more calories if you do the activity in higher heat that makes you sweat more? Like, is running a mile in 90 degree heat going to burn a lot more calories than running that same pace on a treadmill in an air-conditioned room?

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our calorie expenditure is generally based on your body weight, workout intensity and duration of physical activity. However, exposing your body to hot temperatures during exercise does affect its calorie expenditure because of your body's need to cool itself, according to the American Council on Exercise. However, if you're going to work out in extreme heat, beware of dehydration and other heat-related illnesses, according to authors of a 2011 review in the "Journal of Athletic Training."

Hot vs. Cold Temperatures

According to the American Council on Exercise, you will indeed burn more calories in extreme heat than in moderate, more comfortable conditions. This is because your body expends additional energy trying to cool itself by pumping blood to your skin and sweating. On the flip side, working out in extreme cold temperatures -- which can cause your body to shiver -- may burn even more calories than sweating in extreme heat. This is because shivering is your body's way of expending energy to regulate your body temperature. ACE reports that shivering alone can burn 400 calories per hour.

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Some basics to start. In general, you burn a mix of fat and carbs when you exercise. The more intense the exercise, the more that mix shifts toward carbs and away from fat. So the "first approximation" answer is that since running 9:00/mile requires a higher intensity in hot conditions than in cool conditions, you'd expect to burn a higher proportion of carbs in the heat.

But heat affects the body in a lot of different ways, so we have to ask whether the body's fuel preferences change in hot conditions. It turns out that they do. As this Spanish study from 2010 noted:Exercise in the heat (40 C) increases muscle glycogen oxidation and reduces whole-body fat oxidation (Febbraio et al. 1994), in comparison to the same exercise intensity performed at 20 C

This makes the effect even more pronounced: not only does running in the heat increase your intensity (which increases the carb:fat ratio), but it also increases the carb:fat ratio even at the same intensity. So we can say pretty definitively that running at 9:00/mile in the heat burns a higher proportion of carbs and lower proportion of fat than running at the same pace in cooler conditions.

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I suppose I am impressed by people who run marathons and all that, but it's just sooooo damn boring I genuinely don't understand it. Why not do exercise that is fun, or go kayaking, paddleboarding, or trailrunning at least? The mudruns and spartan races can be fun also.

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Fealorn_sl said:

I mainly run marathons although I have done some half marathon and 30km races. My PB is 3:02, I'm working on running a sub 3 marathon, hopefully this fall if I can improve my diet and stop eating crap. I'm up to 13 marathons so far including a couple Boston's. I did the Boston to Big Sur challenge this year.2 marathons 6 days apart.awesome experience.

To the people that say running is boring, to me its peaceful. I love going for my long runs early Satruday mornings when its quiet and no one is on the roads except the odd runner, and I only train outside. Since I live in Canada I also run through the winter outside.regardless of weather.

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