Getting the most out of your body during training and competition requires that you pay attention to what you put into your body while it’s active. The body simply can not operate at its peak unless it is well hydrated and properly fueled.

Hydration

Research shows that many athletes begin training and competition already dehydrated, and then make matters worse by failing to drink enough during exercise. Keeping dehydration to a minimum is a powerful way to improve performance. Staying well hydrated is often a real challenge for athletes because total daily fluid needs can be large – ranging from 2 quarts to more than 10 quarts. That large range is due mostly to differences in how much sweat is lost during exercise because sweat loss varies widely among athletes. For example, some athletes are light sweaters and lose relatively little fluid during exercise. Other athletes are heavy sweaters and can dehydrate quickly if they are unable to drink enough during exercise. It’s also important to remember that sweat loss can change dramatically from one day to another depending on the environmental conditions, exercise intensity, heat tolerance, clothing & equipment, and hydration status. In other words, an athlete might only lose a quart of sweat during a day that includes an easy workout and five quarts of sweat during tough workouts the next day.

Electrolyte losses in sweat – especially sodium – can also be large. In some athletes, the sodium lost in sweat during a two-hour workout can amount to 5 grams or more – the equivalent of two teaspoons of table salt or the amount of sodium in 45 pretzels. Electrolytes such as sodium are a critical part of hydration because electrolytes enable the athlete’s body to hold onto the fluid that is consumed during exercise.

Fueling

The only way to minimize dehydration and maximize the benefits of hydration is to drink fluid during exercise. Drinking also makes it easy to consume another nutrient vital to peak performance – carbohydrate. Active muscles rely primarily on carbohydrate for fuel and supplying muscles with extra carbohydrate boosts performance during intense exercise. Sports drinks contain carbohydrates such as sucrose, glucose, and fructose, all of which can be processed by the body into extra fuel.

Practical Advice

The simplest advice is to begin exercise well hydrated and drink enough during exercise to minimize dehydration (weight lost during exercise). Athletes should take care to avoid over-drinking (weight gain during exercise) that can increase the risk of symptomatic hyponatremia (a disorder caused by low blood sodium).

To develop a hydration plan that works for you, here are some suggestions to keep in mind …

BEFORE EXERCISE

• Staying well hydrated throughout the day benefits the athlete’s body because dehydration slows muscle recovery and repair. Be sure to drink plenty of fluid with each meal to help meet your hydration goals.
• Ask yourself three questions each morning: 1) Am I thirsty? 2) Is my urine dark yellow? 3) Is my body weight substantially less (e.g., 2 lb or more) than the day before? If the answer to at least two of those questions is “yes,” dehydration is likely.
• More on urine color: if your urine is light yellow, like lemonade, that’s usually a sign of good hydration. Dark urine (like the color of apple juice) signals dehydration and the need to drink more. Some B vitamins can cause urine to turn bright yellow, so if you recently ingested a vitamin tablet, don’t pay attention to the color of your urine until later in the day. Crystal-clear urine often indicates over-hydration and the need to cut back on fluid intake.

DURING EXERCISE

• Most important, drink small volumes of fluid at regular intervals (e.g., every 15 minutes.) Athletes who lose little sweat might only need 14 oz (about 400 ml) of sports drink or water each hour – roughly 3-4 oz every 15 minutes. Athletes who sweat a lot might require four times as much or more. That wide range is why it’s important to determine your personal hydration needs during training.
• You are unique, so don’t copy the hydration practices of others. Some athletes will need less fluid than you do, while others will need more. Periodically weighing yourself before and after a workout makes it easy to fine-tune your hydration needs. If you lose more than 2% of your body weight (e.g., 3 lb for a 150-lb athlete; 1.4 kg for a 68-kg athlete), increase your fluid intake the next time you exercise. If you gain any weight at all, cut back on fluid intake in future training sessions. After some trial and error, you will become good at gauging your hydration needs.
• You can choose to drink both water and sports drinks during exercise. Keep in mind that sports drinks provide benefits that water does not. A properly formulated sports drink contains the water, carbohydrate, and electrolytes required to help you perform at your best. Research shows that carbohydrate improves performance by providing muscles and brain with extra energy. For example, a 120-lb (55-kg) female athlete should ingest around 55 grams of carbohydrate per hour of exercise, whereas a 200-lb (90-kg) male athlete should ingest roughly 90 g/hour. That carbohydrate can come from sports drinks, carbohydrate gels (with sufficient water; about 16 oz of water per packet of gel), or other sources of carbohydrate. There is no benefit in exceeding 0.5 gram per pound (1 g/kg) per hour because the body has a limited capacity to burn the carbohydrate ingested during exercise. As an example, one quart of a sports drink typically contains 60-70 grams of carbohydrate.
• Be ready to alter your fluid intake based on the conditions of your workout or competition. If it’s hotter or colder than expected, adjust your fluid intake accordingly. The same is true if you find yourself working out easier or harder than expected. Lower intensities of exercise generally mean less sweat loss, so less fluid should be consumed.

AFTER EXERCISE

• There is often no rush to rehydrate unless you are significantly dehydrated (loss of body weight > 2%) or are planning to exercise again that day. To rehydrate quickly, drink 20-24 oz (570-685 ml) of fluid for every pound (16 oz; 0.454 kg) of body weight you’re down. The extra fluid is needed to help make up for the urine you’ll lose before your next workout or competition.
• Electrolyte losses – especially sodium – can be large. If you lose a lot of sweat or if you finish workouts with your skin or clothes caked with white salt crystals, your diet should contain enough salt to replace those losses. Salting your food to taste and choosing some salt-rich foods (e.g., pretzels, tomato juice, chicken-noodle soup) will usually suffice.

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