The short-lived season Philadelphians call "Spring" appears to be over. Tomorrow, it's official: summer, with its stagnant humidity and oppressive heat, is here to stay. The high temperatures will certainly have an effect on your body - and will probably slow you down, but they don't have to stop you from exercising outside altogether. Understanding the physiological changes your body undergoes when working out in the heat can help you make smarter and safer decisions about continuing to do it.When its ultra hot, your body's main concern is cooling itself down, which is does through perspiring. As sweat evaporates from the skin, it cools the body. (Think of the way rubbing alcohol feels cold on the skin as it quickly vaporizes.) Sweat's downside is that it reduces overall blood volume, forcing your heart to pick up its pace in order to do the same amount of work. On a hot day, you might feel your heart rate sky-rocketing for a task that normally feels easy.
A second method of regulating body temperature lies in blood redistribution. Your body directs more blood to the skin to dissipate heat (this is why your face gets so red), therefore less is available to the working muscles/organs. Reduced blood flow to exercising muscles is another reason why your normal workout intensity may feel compromised.
That's the nerdy scientific background on exercising in the heat - even Temple couldn't take the geek out me - but here is a user-friendly and practical checklist for how to handle these effects:
- Realize that you are not going to set any records in the heat. If you typically run a 9 minute mile with ease, don't be surprised when it feels nearly impossible on a hot day. Slow down. Respect that your body has a tremendous responsibility to regulate its temperature - your brain doesn't function at 105 degrees!
- Avoid exercising when the sun is higher in the sky, between 10am and 4pm.
- Wear synthetic clothing that wicks away sweat. Remember, sweat has to evaporate off of the body in order to cool it. Cotton clothing will soak up sweat and cling to you, leaving no room for this process.
- Wear light-colored clothing. White = good. Black and navy = bad.
- Stay hydrated. Plan your route around water fountains or carry a water bottle.
- Try to stay in shady areas.
- Don't be afraid to take breaks!
4 comments:
I feel like the more I sweat the harder I'm working but that may be more a function of the temperature than my effort. How do you feel about drinks (as opposed to water) that supposedly replenish minerals and electrolytes that are leeched out in sweat especially if you drip buckets in an hour's workout.
So I take it the red face, extreme in my case, is nothing to be concerned about. I get several shades brighter than the people around me and it takes awhile to get back to where I don't look like I'm going to keel over. I look much worse than I feel actually.
I think Gatorade and other "electrolyte refills" aren't necessary unless you're exercising for more than 45 minutes to an hour.
I wouldn't be worried about the red face unless you start to feel nauseous, dizzy, or overheated. I've been known to turn a little purple myself - thanks for that gene!
Thanks for this info!! The work-outs have changed due to the heat and water is needed ALL THE TIME it seems.
There's an interesting piece in the Times today(http://www.nytimes.com/2008/07/03/health/nutrition/03Best.html?_r=1&ref=health&oref=slogin)
about working out in the heat. It points out mainly what you did in your post, with a few exceptions:
The article's sources claim that, using marathon runners as an example, the fastest runners only lose about 2.5% of their power/energy going from a cool to a hot/humid day, whereas slower runners suffer about a 12% loss of energy. They say this is for several reasons: slower runners tend to run in packs, intensifying the heat; and they're on the course longer, and therefore are exposed to the heat/humidity for a longer period of time.
The article's final point? That if you exercise in hot, humid weather and get used to it, your body can become accustomed to performing at that level in that climate (what i imagine is similar to working out in high altitude).
Makes sense, but it sounded suspect to me, and dangerous. Unless I suddenly become a professional athlete (ha!), I'm playing it safe.
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