Heat, stretching and warmups

This article was originally posted by Ryan at the original HillRunner.com Blogs.

In an ironic twist, a day after my post on summer running went live I came across a study on what about the heat affects us. Also this week, pre-exercise static stretching and a better way to warm up?

First, what is it about the heat that affects our running? For the longest time, we’ve been told it’s that our core temperature rises to near dangerous levels and our bodies shut down to protect themselves.

Well, what if that’s not the case?

There were no group differences in core temperature and heart rate response during the exercise trials.

This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.

In short, the study had runners running in temperatures of roughly 64, 79, 93 and 108 degrees farenheit. It found no statistically significant difference in core body temperature or heart rate between runners running at these different temperatures. What it did find was that the difference between core temperature and skin temperature was lower and sweat rate was higher in the higher temperatures. The suggested conclusion is that these factors, not core body temperature, are what actually affect our performance in the heat.

Of course, this is just one study. It would be nice to see some follow up to see if others can produce the same results.

Assuming these results can be reproduced, though, how might we act on this? Well, I’ve always been a fan of pouring cups of water over your head and/or body at aid stations when racing in the heat. That would help cool your skin, which according to this would help your performance. Anything else you can do to help cool your skin would, presumably, do the same. This is probably the mechanism by which those chill vests some elite athletes use before warm weather races work.

Second, does static stretching affect our performance

The going concern over pre-exercise static stretching is that our power output is reduced. Well, it is…in some cases.

Basically, this goes back to something I have been seeing a lot of recently. If you static stretch a muscle for more than 45 seconds, its power output is reduced. If you static stretch for less, no reduction in power output.

So, if you feel like you need static stretching pre-run, do it. Just don’t hold it for too long. Personally, I’ve always felt better in races when I did some stretching pre-race but I don’t hold the stretches for long. So my takeaway from this is keep doing what I’ve been doing. That’s probably the takeaway most runners should get from this.

Finally, make sure you do some harder running in your warmups

I’ve long been a fan of warmups that increase in intensity. Start very easy, build up over time and finish with some strides at or slightly faster than race pace shortly before the start of the race. It’s just the way I’ve been taught to do my warmups and it makes intuitive sense. You’re preparing yourself to run hard so why wouldn’t you run hard as part of that preparation?

Scott Douglas writes about a study to delve into this a little deeper with some interesting results.

In short, runners did some strides and moderately paced running as part of warmups twice. In once case, they wore weighted vests during the strides. In the other case, they did not. After wearing the weighted vests, their running economy and peak speed improved.

What to make of this? Should we all go out and buy weighted vests? One interesting idea that comes to mind for me is using skipping exercises for exaggerated power output. Another is doing something like Jay Johnson’s lunge matrix, which I know he has mentioned as a good pre-race routine.

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