Ever felt queasy after an exercise routine?
Imbalanced electrolytes could be to blame. In fact, if they are seriously imbalanced, you could even experience excessive sweating, vomiting or diarrhea.
The major electrolytes lost in sweat are sodium, chloride and to a lesser extent potassium. Physiological adaptive mechanisms decrease the electrolyte loss in urine and sweat during periods of strenuous exercise, thus the sweat of a trained athlete is more diluted than the sweat of an untrained individual.
However, athletes who sweat profusely for a period of days, who are not acclimated to the heat, or who have low sodium intakes can experience heat cramps from sodium depletion.
Potassium losses in sweat can generally be replaced with a diet. Foods rich in potassium such as citrus fruits, juices, melons, strawberries, tomatoes, bananas, potatoes, meat and milk can be consumed.
Fluid replacement occurs in three general time frames: before, during and after exercise. The ultimate goal is to start the exercise period in a hydrated state, avoid dehydration during exercise and re-hydrate before the next training session.
Consuming at least (0.5L) of fluid two hours before activity provides the fluid needed to achieve optimal hydration and allows enough time for urination of excess fluid. Because rapid absorption is not critical, athletes can drink water or any other non-alcoholic beverage. The fluid can be consumed with or as part of a meal.
Athletes may not voluntarily drink enough fluid to replace sweat losses during exercise. The goal of fluid replacement during exercise is to move the fluid from the mouth, through the gut and into circulation rapidly and to provide a volume that matches sweat losses. This is achieved by providing fluids that are absorbed rapidly and that the athlete finds palatable.
Athletes should start drinking before sensing thirst and continue to drink at regular intervals. Larger volumes tend to empty from the stomach more rapidly than small volumes.
A variety of fluids can serve as effective fluid replacements during exercise. Cool water is an ideal fluid replacement. Other options for fluid replacement include commercial sport drinks. Aside from promoting water intake, there does not appear to be a physiological benefit from carbohydrate consumption for athletes participating in events less than one hour long. However, aerobic endurance athletes, such as distance runners, swimmers and soccer players, can benefit from carbohydrate provision with water intake during activities lasting more than an hour.
The goal after an exercise session is to prepare the body for the next exercise session. Monitoring body weight and replacing each kilogram lost with fluids is important to ensure adequate fluid intake. Urination occurs before complete fluid balance is achieved. When significant sweating has occurred, consumption of sodium chloride (salt) in the form of beverages or food minimizes urine output and hastens recovery of water and electrolyte balance.
Fact: Most fluid consumption occurs during and around meal times and the source of the water is from both food and beverages.
The best advice is to drink plenty of fluids often between training or practice and do not rely on thirst as a guide to fluid intake.
What about Sports Drinks?
Commercial sports drinks contain water, sugars and electrolytes (usually sodium, chloride and potassium). Carbohydrate concentration of commercial sports drinks ranges from 6% to 8%, a solution that tends to absorbed rapidly.
Carbohydrate drinks have become a popular alternative to sugary carbonated drinks and they are healthier. Not all athletes tolerate beverages or foods other than plain water while exercising.
Fluid Replacement Guidelines
- Hydrate properly before prolonged exercise in a hot environment. Consume a cool beverage two hours before a workout.
- During activity you should drink fluid frequently – for example (177-237ml) every 15 minutes.
Have fluids readily available, since the thirst mechanism does not function adequately when large volumes of water are lost.
- After a workout, you should replenish fluids at a rate of exceeding (0.5L) for every kilogram of body weight lost. Weight should be regained, indicating re-hydration has occurred before the next workout.
- Water is an ideal fluid replacement, although flavored beverages may be more effective at promoting drinking. The addition of salt in beverages or as food can promote re-hydration more effectively than plain water when significant weight has been lost through sweating.
- The ideal fluid replacement beverage depends on the duration and intensity of exercise, environmental temperature and the athlete.
Nutrition for Fitness and Sport - Melvin H. williams
Asthma & Exercise
New Treatment for Diabetes?