Avoid Dehydration When Exercising
When to replace electrolytes
- If you have diarrhea or vomiting, you can lose an awful lot of mineral electrolytes, so you should replace them right away.
- If you're performing exercise in temperate conditions for less than two hours, it may not matter.
- But if you're exercising in the heat, you probably want to start replacing electrolytes relatively soon.
The general rule of thumb is that if you're exercising and having high sweat rates for any prolonged period - let's say over an hour - you probably then want to replace the electrolytes at a rate proportionate to what you're losing.
Sports drinks contain electrolytes in concentrations proportionate to what is lost in sweat by a moderately trained athlete. The National Academy of Sciences has looked at sports drinks, and the general conclusion is that they have their place under certain circumstances.
When you are doing high intensity exercise of a prolonged nature, the carbohydrates and the electrolytes sports drinks have, can provide benefits. The sodium content stimulates thirst and make it easier to hold the water ingested, and provides the energy that's needed to sustain physical activity. Athletes participating in hot weather training should consider their use.
But for the average person, maybe just engaged in a game of tennis or similar intensity, replacing carbohydrates and electrolytes is probably not a concern. See When You Need A Sports Drink.
Signs of dehydration
One way to check hydration is by monitoring body weight. If you take your body weight every morning, it will normally be relatively constant. If however, it's down a lot one morning then this is probably indicative of dehydration.
Another way to identify dehydration is to monitor urinary habits. If you're urinating more frequently than usual, and if it's relatively clear, you're probably very well hydrated. If, on the other hand, you're urinating infrequently and it's dark, you're probably dehydrated. But there is no unique relationship between urine color and dehydration.
One of the things that you often see with dehydration is elevated body temperature. If a person is exercising in the heat, this causes greater than normal elevation in the body temperature, and cardiovascular strain.
You should drink plenty fluids, maybe an hour before you exercise. You want to stay away from carbonated beverages and those with high fructose content because they can cause gastro-intestinal problems.
However, after exercise, you are free to drink whatever you want. It is important to note that most people fully rehydrate at mealtime. So if you're concerned about hydration, one of the worst things you can do is skip meals.
You should try to exercise in the cool of the morning or the evening hours. But if you're like most people, you exercise when you can.
If you are going to exercise in heat, use moderation. Don't exercise on the hottest days and push it. Instead, scale back your activity levels. For example, you can walk instead of run, or run slower or for a shorter period of time.