postheadericon Rogaining and Fluid Intake

by Di Challen

Maintaining an adequate fluid intake is critical to optimal athletic performance, particularly for the endurance athlete. During a marathon, for example, a runner may lose 2-6% of his body weight due to water loss (despite taking in fluids during the event), and for each percent of body weight lost by dehydration, his pace decreases by about 2%. With the 1997 Upside Down Rogaine approaching, the following information may be of interest to those of you intending to compete in what can be a fairly warm event.

According to a number of authors, you should drink 150-250ml of fluid every 15 minutes during a sporting event. They obviously didn't have Rogaining in mind when they made this recommendation. This means you have to consume 14.4-24 litres in a 24 hour event or 7.2-12 litres in a 12 hour event - somewhat difficult to achieve when you have to carry the fluid yourselves and when there is often considerable distance between water drops. Of course, these figures depend on environmental temperature; in hot conditions you will lose more water through sweating and in cold conditions, you will lose less.

The very nature of Rogaining means that it is unlikely that you will be able to consume adequate amounts of fluid during the event. The following recommendations may help you to avoid severe dehydration and heat related illness:

  • Drink 300-500ml (2-3 cups) in the 30 minutes before the start of an event.

  • Drink as much as practical during the event. When you reach a water drop, fill yourselves up as well as your water bottles.

  • Drink at least 500ml immediately after the event.

You do not begin to feel thirsty until well after your body has begun to dehydrate, so don't rely on thirst as an indicator of your fluid needs.

As a rule of thumb, if you are not urinating at your normal frequency and your urine is not clear, you are not drinking enough.

Sports drinks are always a subject of contention among athletes. The carbohydrates in sports drinks (such as glucose) are useful in replenishing your energy stores, although eating something solid will provide you with considerably more energy. The carbohydrate content of the drink should not be greater than 8% (ie 80g per litre), otherwise it will slow the rate at which water is emptied from the stomach.

Salt is added to sports drinks not as a replacement for the salt lost in your sweat (which is relatively small, and quickly replaced when you consume many foods), but because it supposedly increases the rate at which fluid is absorbed into the bloodstream. Not all research supports this claim.

Probably the greatest value of a sports drink is that is tastes better than water alone, encouraging you to drink more. A cheaper and equally effective alternative to a sports drink is cordial (not too concentrated) - with a small amount of salt added to improve the rate of absorption.

And finally, a word of caution: don't take salt tablets. They can cause dehydration and stomach upsets, and they don't relieve cramps. (Some people swear by salt tablets as a remedy for cramp. However, it is thought that cramp is caused  by dehydration and perhaps salt tablets appear  to  work for these people by increasing their thirst and causing them to drink more thus relieving their dehydration.)

Although you may not be able to consume adequate amounts of fluid during a Rogaine, the fitter you are, the better your body copes with heat stress and the less likely you are to suffer from dehydration and heat related illness.

Cardwell, G. (1996). Gold medal nutrition. Bentley, WA: Glenn Cardwell.

Wilmore, J.H. & Costill, D.L. (1994). Physiology of sport and exercise. Champaign, IL: Human Kinetics

Last Updated (Sunday, 04 July 2010 16:05)

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