Adventure News: Avoid Heat Stress When You Ride, With These Stay-Cool Tips

Adventure News: Avoid Heat Stress When You Ride, With These Stay-Cool Tips - Ndorfin, South Africa

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Monday, 26 July 2010
Avoid Heat Stress When You Ride, With These Stay-Cool Tips

In summer, cyclists must adjust to heat. Many of us must adjust to all kinds of hot weather from the scouring, dry heat of the United States� West Coast to the wilting humidity of the South.

Heat stress occurs when high humidity, radiant heat from the sun and elevated air temperature combine to impede your body�s ability to dissipate heat. It also places considerable demands on your body�s physiological control mechanisms.

To train and compete at your best all summer, it is important to understand how your body copes with heat, and what you can do to keep cool.

Eliminating heat from your body

Your skeletal muscles can use only about 25 percent of the energy available to them to generate force; the other 75 percent of energy is released as heat During prolonged cycling, heat production can potentially raise your body temperature nearly 2 degrees Fahrenheit every five to eight minutes.

If the body did not adjust to this condition, exercise would be limited to about 20 minutes before elevated body temperature caused fatigue.

But exercise can be sustained for longer than 20 minutes, so your body must possess some mechanism(s) to dissipate heat. In fact, there are four ways that excess heat produced by muscle contraction can be removed from the body: conduction, convection, radiation and evaporation.

Excessive heat strain during exercise usually does not occur unless temperature and humidity are high, the air is stagnant, you do not rehydrate effectively, or you are not adequately acclimatized to the heat all of which happen during the summer months.

However, when cycling, the wind moving across your body can usually remove the heat produced. This is convective heat lost, and is related directly to wind speed.

Sweating is important to help regulate body temperature during hard training. As sweat evaporates, heat is removed from your body. However, humidity impairs this cooling mechanism, since air is already saturated with water and sweat doesn�t evaporate as easily.

While sweating is necessary to help cool the body, the production of sweat comes at the expense of your body fluids. As much as 1 to 2 quarts of fluid per hour may be lost as sweat while cycling in very hot weather. To help you understand the seriousness of this, the loss of as little as 2 to 3 percent of your body weight due to dehydration can impair exercise performance.

Therefore, to help maintain adequate hydration and prevent heat illness during prolonged cycling in the heat, it is vital that you acclimatize and that you replace fluids lost through sweating.

Keeping your cool

Here are a few suggestions for preventing heat stress and adapting your program to the demands of summer training or competition.

When the first hot spell of summer hits, gradually work your way up to several hours of exercise in the heat during your first few training sessions. A gradual build-up in distance and intensity should be completed by the seventh to 10th day of training.

But everyone adapts differently to heat stress. In order to help your own body adjust, make sure you adapt gradually to a hot environment.

Time of day is crucial. While you may have acclimatized to conditions in the morning, you still need to take steps if you are going to race during the heat of the day, when the heat is highest (noon to 3 p.m.). Over the last few days before an event, make a point of riding at that time of day to enhance your adaptive training. If you can only train in the morning, then wear extra clothing to purposely increase the heat stress.

As stated earlier, during hard training you will lose 1 to 2 quarts of fluid through perspiration each hour. If your fluid loss by sweat or urine exceeds your fluid intake, you will experience dehydration.

Body weight losses in the 3 to 4 percent range impair the body�s ability to efficiently utilize oxygen. When dehydration causes more than 4 to 5 percent weight loss, your power will deteriorate tremendously. Always be aware that even during non-athletic activities, in hot and humid conditions your fluid losses will typically range from 1 to 10 quarts every 24 hours.

To combat this, begin drinking even before you get on the bike. Drink 8 ounces as you are getting out the door. During your ride, try to drink at least 8 to 12 ounces by sipping fluids every 20 minutes (make sure you sip, not gulp, to avoid stomach discomfort).

If you cannot carry enough fluids in your water bottles, wear a back or hip-mounted hydration system to ensure you drink enough. Such systems also keep fluids colder, and cool drinks tend to taste better, so you are apt to drink more.

There is evidence that after-exercise carbohydrate-electrolyte beverages replace lost fluid in the blood at a slightly faster rate than pure water.

To make sure that you are properly hydrated, weigh yourself before and after hard training sessions in the heat. If you finish a training session with a weight loss of more than 3 to 4 percent, you should practice drinking more while on the bike.

You can assess the status of your body�s fluid level by the volume of urine expelled. An adult�s urine volume is about 1.2 quarts every 24 hours. If your daily urine volume is less than 1 quart a day, your body is conserving water and you should consume more fluids.

Urine that is dark and yellow also indicates you may be dehydrated, and that your body�s cells are being put under undue stress. If you experience frequent cramps, have your salt intake evaluated by a sports medicine physician or dietitian.

Keeping track of your body weight on a daily basis is an effective way to determine water loss. When you get out of bed in the morning, step on a scale. Record your weight in your training diary. If you experience a weight loss of 1 to 3 percent from the previous day�s activity, avoid beginning a training session or competition until you are rehydrated. Do this by drinking 16 ounces of fluid for each pound of body weight lost.

Lastly, wear a white or light-colored jersey to reflect radiant heat as much as possible. Wear clothing incorporating new materials that allow for greater transport of air and moisture to flow in, out and over your hot body. Do not use oil-based sunscreens, which impede sweating.

Training, acclimatization and the proper use of sport drinks will help you perform your best in summer heat. The bottom line on all of this is to know your body and take care of it.

If you use common sense and prepare properly for competition in the heat, nothing should stand between you and an excellent finish. Remember, you can�t change the weather, but with a little planning, you can beat the heat.

Author: Edmund R. Burke (26 Jul 2010) courtesy of ENTRYTIME - www.entrytime.com�