Much is made of hydrating before, during and after exercise. But depending on the duration and intensity of your activity, you might not need to carry a water bottle throughout your workout. For most of us, a good rule is to drink when you’re thirsty. If you are engaging in intense exercise (a multihour race, for example) or will be out all day — say, on a long hike — you should try to take fluids even before you feel thirsty.
But what to drink?
Water. It’s essential for life, unlike soft drinks, beer and many other beverages. Fruit juice may have vitamins and minerals, but it also contains sugar (and calories), thereby making it harder for you to lose weight. And because you body has to process that sugar, you may feel a temporary energy lag if you drink sugary beverages immediately before or during exercise.
Besides, you can get those vitamins and minerals in a purer form simply by including fruit in your diet.
What about the much-hyped and heavily advertised sports drinks? Aren’t those made for everyone who exercises? Not necessarily.
As many experts point out, sports drinks can help maintain and restore your electrolyte balance if you’re exercising strenuously for an extended period of time in warm temperatures. But some sports drinks have high sodium content, which is something to avoid for anyone who takes medication that raises or lowers blood pressure. Excess sodium can cause a spike in blood pressure.
You could try a sports drink with a low sodium content. But why bother? Water is that rare thing that does exactly what it’s supposed to do — rehydrate the body — without any extra calories, needless sugar or added coloring. It’s refreshing. It’s plentiful. And it’s free (although if you don't trust your municipal water supply, you might need a water purification filter).
One caveat, which is very unlikely to impact most of us: You might actually need to replace sodium lost during sweating if you are engaging in extremely strenuous exercise. In extremely rare cases, people who have exercised strenuously for extended periods (running a marathon, for example) while consuming only water have suffered from hyponatremia, which is essentially a sodium deficiency in bodily fluids.
How much should you drink? Some serious fitness buffs strive for total hydration — for example, sipping so much water throughout the day and during exercise that the color of their urine is always clear. You don't need to be that extreme, although dark yellow urine can be a sign of potential dehydration.
The Mayo Clinic recommends around eight cups a day for most adults, plus another two to three cups for short bouts of exercise. Increase that amount in high heat and/or humidity. Drink a little water before working out, then take small sips during exercise, if possible.
Carole Carson, author of From Fat to Fit: Turn Yourself into a Weapon of Mass Reduction, serves as the coach for the AARP Fat to Fit online community.