Feel the Burn!

WNBC—NEW YORK—July 11, 2007

Reporter: Even in excessive heat, many die-hard athletes stick to their workout routines, overdoing it, though it can have health consequences. Joining us now with advice on how to safely exercise during the summer months is Jordan D. Metzl, M.D., sports medicine specialist at Hospital for Special Surgery in New York. Why is it dangerous to be going out in this heat and exercising with the high humidity?
Dr. Metzl:

We donít want to scare anybody. It could be dangerous, but as long as youíre smart about how you exercise in the heat, itís not necessarily a deal breaker.

The first point I want to make is thereís something called the bold indexóitís a combination of the heat plus the humidity. So if youíre in Arizona and itís very hot, you might notice you can exercise without really overheating, but in New York, on the east coast, we often have really high humidity and high heat together. When those two things happen simultaneously, when you sweat, it doesnít evaporate, and you canít cool your body so youíre more prone to heat illness.

Reporter: So why does it impact your heart?
Dr. Metzl: It impacts a number of different body systems. When you start to sweat and you become dehydrated, you can have a number of different medical problems and some of those can be quite serious. In the long term, it can affect your heart, but there are some other things that can happen sooner than that.
Reporter: Letís say you still want to exerciseóyou donít want to hang it up. What should you do to prepare?
Dr. Metzl:

Itís important if itís quite hot outside, you have to really get used to it. Your body actually acclimatizes to heat, so you want to make sure you donít just go out on a very, very hot day and say, ďIím starting my exercise program today.Ē You want to make sure you gradually get used to the heat, and you will get used to it.

If you can, try and avoid peak heat hours. Try to exercise early in the morning, late at night, and also you have to drink a little bit more before you exercise and throughout the day.

Reporter: You should have a very large water bottle there.
Dr. Metzl: Thatís right. As a woman, you actually lose two liters a day from just normal sweat. Men lose about three liters a day, even if they donít do much exercise. If you exercise, you lose about four to five of these a day.
Reporter: So how do you know how much water you should be drinking? Do we still say eight cups of water a day?
Dr. Metzl: That comes off of how much weíre losing. You really want to replace how much youíre losing. If you really want to replace those losses, in the summer you should increase that. You see these people walking around New York with water bottles, and you can kind of laugh at them, but they do have the right idea in most cases.
Reporter: How do you know when you are actually dehydratedówhat are the signs?
Dr. Metzl: There are some signs of dehydration from very mild to severe. You can just become lightheaded or you can become dizzy. In further evolved dehydration, you can become nauseous. Then, when you become severely dehydrated, you donít sweat at all. If you ever see anybody in that situation, theyíre at risk of developing heat illness, which is much more serious than just dehydration.

To view the full interview, visit WNBC.com.

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