Athletes are very familiar with the negative effects of dehydration. Even a drop in body weight as small as 1.5% (about 2.5 pounds in a 165-pound cyclist) due to fluid loss can decrease your endurance.
Sweat rates vary from athlete to athlete, but can easily range from 1 to 2 quarts per hour, or even more in some individuals. Fluid losses clearly can add up during longer training sessions.
Depending on your chosen sport and your workout for that day, it may be easy to consume fluids during exercise, or it may not. Various training and racing scenarios make drinking accessible, while others present very limited drinking opportunities. But even the best exercise guzzlers can struggle to keep up with endurance fluid needs in challenging environmental conditions.
Because of these challenges, pre-hydrating to achieve a state of hyperhydration -- in which greater than normal body water can be stored -- presents another option in maximizing your athletic performance.
Why prehydrate?
Start any training or racing situation in the euhydrated state -- with normal body fluid stores. But don't leave any pre-exercise hydration efforts to the last minute.
One lab study has shown that drinking even 2 full quarts of water over 45 minutes when already dehydrated, only replaced 60% of fluid losses. Much of this large fluid intake may also go toward urine production. So "catch-up" drinking is not the most effective hydration strategy.
If you anticipate that your sweat loss will not be easily replaced with drinking during exercise, it is better to hyperhydrate than not, though hyperhydrating is certainly not considered as effective as drinking enough fluid during exercise.
But keep in mind that athletes typically replace about 50% of their sweat losses during exercise, and even the "best drinkers" may only replace up to 80% of their sweat losses. So hyperhydrating could help delay dehydration in many training situations.
Hyperhydration strategies
First of all, try at all costs to avoid beginning exercise in the dehydrated state. In the evening, drink 16 ounces of fluid. Your morning intake should also consist of 16 ounces of fluid. Of course, caffeine-free fluids have the best hydrating effect.
Next, if you train early in the morning, attempt to drink 4 - 8 ounces of fluid every 15 - 20 minutes during exercise.
If you do not train in the early morning, consume 8 - 10 ounces of fluid every hour during the day, after your 16-ounce morning intake. Then prepare adequately for a training session later in the day. About one hour before exercise, you can hyperhydrate by consuming 16 - 32 ounces of fluid. At this time, fluids such as sports drinks, which provide carbohydrate and small amounts of sodium, are likely to be the best choice and may have some hydration advantages over water.
After this one-hour pre-exercise fluid intake, fill fluid stores to the brim by drinking another 8 - 16 ounces fluid, 20 minutes prior to training.
It is best to practice these fluid-intake guidelines prior to training. Some athletes may experience gastrointestinal discomfort with these large recommended fluid volumes. If your current intake needs to be increased in order to hyperhydrate, increase volumes slowly and assess your own personal tolerances.
Don't forget to drink adequately during training whenever possible. About 4 to 8 ounces every 15 to 20 minutes is recommended. For exercise lasting longer than 60 minutes, you may want to consider use of a sports drink.
One of the best gauges of your drinking efforts during exercise is to weigh yourself before and after training. Every pound of weight loss represents 16 ounces of fluid loss. However, to compensate for urine losses when rehydrating, consume 24 ounces of fluid for every pound of weight loss after exercise.
If your pre- and post-exercise weigh-ins do reflect some fluid loss, you need to practice drinking more during exercise.
Monique Ryan, MS, RD is a sports nutritionist and author of "Sports Nutrition for Endurance Athletes." For information on her programs visit moniqueryan.com or to purchase her book Sports Nutrition for Endurance Athletes click here. She provides sports nutrition programs for endurance athletes of all levels all over the country, and has worked with professional triathletes, the Saturn Cycling Team, and is a member of the Performance Enhancement Team for USA Triathlon.
Listen to our interview with Monique Ryan on the Sports You Do Show, in which she answered your nutrition questions!
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