• Pre – exercise: Generous amounts of fluids should be consumed through the day - 8 to 12 cups of fluid is enough for most individuals. ‘At least 480ml of fluid must be consumed before exercise’, says Prof Rabindarjeet.
• During exercise: Prof Rabindarjeet also recommends 1/2 to 1 cup of fluid every 15 to 20 minutes, through an exercise session, beginning at the start of a workout.
• Post – exercise: Ms Sunarja, Dietitian, for the Singapore Sports Council, recommends 2 to 3 cups of fluid within a few hours of exercise to restore hydration.

The Fluid Choices

• Water: Dr Kallaya Kijboonchoo, Associate Professor, Mahidol University Thailand, says ‘Water is the best fluid before, during and after exercise, for an exercise session that lasts less than 60 minutes’.
• Sports Drinks: For those who engage in intense or prolonged activity, Dr Kijboonchoo, recommends sports drinks: ‘An hour prior to exercise, a sports drink which aids in gastric emptying is ideal’. Ms Sunarja says a beverage containing carbohydrate in concentrations of 4% to 8% and sodium in amounts between 0.5 and 0.7 g/L is ideal. ‘Presence of carbohydrates helps replenish lost energy after exercise’, says Prof Rabindarjeet. Sodium in these beverages not only increases palatability of the fluid, but also increases the thirst sensation and helps correct salt loss from prolonged sweating. Other electrolytes such as potassium, chloride and magnesium in these drinks not only replace electrolytes lost in sweat, but also aid in retention of consumed fluids and promote rehydration. There are a range of flavorings used in sports drinks and these promote hydration by increasing palatability.
• Juices: Juices and juice drinks are good after-workout choices supplying fluid, carbohydrate and potassium. During a workout however, juices should be diluted at least two-fold (i.e.1 cup water for every 1 cup of juice), for optimal carbohydrate concentration. ‘Juices however, do not provide some of the lost electrolytes (like sodium) and these may need to be obtained from other sources, such as meals, snacks and cereal bars’, says Ms Sunarja.
• Other beverages: Meal supplements, milk shakes and soy milk may be consumed 2 to 3 hours prior to exercise.

Avoid:

• Drinks which contain less than 2% carbohydrate as they are unlikely to extend performance, while those that contain more than 8% carbohydrate are associated with intestinal upset, slow gastric emptying and may contribute to dehydration.
• Beverages containing alcohol, as they increase risk of dehydration associated with increased urine production.
• Drinks with high carbonation, as they may cause a feeling of fullness in the stomach and decrease voluntary fluid intake.
• Drinks with ephedra, as this stimulant does not have a positive impact on performance and is banned from many sporting events.
• Excessive intake of caffeinated beverages, as large doses of caffeine can have a mild diuretic effect. No more than 2 to 3 cups of coffee should be consumed before or during exercise.

Include:

Consider including foods containing a lot of water, such as oranges, watermelons, apples, grapes, lettuce, and tomatoes. These foods provide water and some carbohydrates and are good for replacing lost water and energy after exercise. A range of drinks, such as soft drinks, juice, water, iced tea are suitable to maintain fluid balance. In the case of excessive or prolonged sweating consider replacing lost electrolytes with sports drink or light snacks.

What about Energy Drinks?

Energy drinks which contain high concentrations of carbohydrate, small amounts of herbs, and other ingredients including guarana, ginseng, royal jelly, bee pollen, gingko biloba, green tea, ribose, carnitine, taurine, chromium, vitamins and minerals etc., hold the promise of performance-enhancing effects in a fluid and seem very attractive. However, Ms Sunarja warns that athletes should be careful about taking energy drinks, as the actual contents of energy drinks are not always mentioned on the labels and this may place an individual at risk of taking restricted/banned substances unknowingly.

The Bottom Line

“To stay well hydrated, fluid before, during and after exercise should be the goal of every active individual”, says Dr. Kijboonchoo. Establishing a fluid regimen is important and water, sports drinks, soft drinks, diluted juice and water-laden fruits should be planned into a daily fluid diary. Energy drinks are fine after a workout, if health experts give the green signal for it.

References

• Rabindarjeet Singh, Professor of Sports Science, Sports Science Unit, University Sains Malaysia, Kelantan.
• Dr. Kallaya Kijboonchoo, Associate Professor, Head, Physiological Nutrition Division Institute of Nutrition, Mahidol University Thailand.
• Fahma Sunarja, Sport Dietitian, Sports Medicine & Research Centre, Singapore Sports Council.
• American College of Sports Medicine. Position statement on exercise and fluid replacement. Med Sci Sports Exerc. 1996;28;I-vii.
• Vrigens DMG,Rehrer NJ., Sodium-free fluid ingestion increases plasma sodium during exercise in the heat. J Appl Physiol. 1999;86 ; 1847-1851.
• Nutrients for the athlete. http:www.dietsite.com /SportsNutrition/NutrientsAthletes/ Nutrients%20 Fluid.html9.
• http://outreach.missouri.eduextensioninfoline /nutrition/fluid-replacement.html
• Casa, DJ, et al. National Athletic Trainers Association Position Statement: Fluid replacement for athletes.Journal of Athletic Training. 2000;35:212-224.
• Armstrong L.E. Caffeine, bodyfluid - electrolyte balance and exercise performance. Int. J. Sports Nut. and Exercise Metabolism 12 : 205 - 222, 2002.