You’ve been playing sports long enough to know that dehydration can kill your game: You lose focus, lack energy, and your speed slows dramatically when your body loses too much water through sweat. In marathoning and other endurance sports, scientists estimate that losing any more than 2 percent of your body weight through sweat will result in a significant decrease in performance. Why? Water loss causes a drop in blood volume, which forces your heart to work harder to pump blood to your muscles and vital organs, leading to cramping, slower reaction time, and fatigue.
What you need—and when
To keep yourself feeling strong and energized, you need to take in 6 to 8 ounces of fluid for every 20 minutes of exercise you do over one hour. You’ve probably heard, though, that most exercisers don’t need fancy sports drinks to stay hydrated—that plain H2O will do the trick. While that’s true for anyone doing moderate exercise (i.e. brisk walking) for under an hour, athletes out for, say, a 10-mile run or a 2-hour bike ride are going to need sports drinks or something similar for two reasons: First, you simply need more energy in the form of calories if you’re working out for longer than one hour. The easy-to-digest carbs in sports drinks help replenish your body’s caloric needs—so you can go faster and farther, longer. Second, energy drinks also contain a crucial supply of electrolytes and minerals that your body loses through sweat. In particular, they help replace sodium, magnesium, and potassium.
These three “ingredients” are key to the quality of your workout:
• Sodium: This electrolyte helps maintain the proper fluid balance in and around your muscle cells, allowing for optimal muscle performance. It also stabilizes your blood pressure during exercise.
• Potassium: In addition to keeping your blood pressure low, potassium plays a crucial role during exercise helping muscles contract and release in a smooth fashion. A drop in potassium can trigger serious muscle cramping; it can also lead to irregular heart rhythms.
• Magnesium: According to recent research, magnesium plays a key role in helping transport oxygen to your muscles during exercise. Throughout your workout, your body’s magnesium supply will be redistributed to the muscles that need it most (your quads, for instance, if you are running). Because magnesium also plays an important role in controlling nerve impulses, a drop in its levels will slow your reaction time and reduce your muscles’ ability to fire properly.
Are you a salty sweater?
Is your skin covered with tiny white crystals after a hard run in the summer heat? Then you’re what’s known as a “salty sweater,” meaning you should be extra vigilant about replacing lost sodium, potassium, and magnesium. While H2O will increase your blood volume (so your heart doesn’t have to work as hard to pump blood throughout your system), it can’t replenish lost electrolytes the way common sports drinks like Gatorade or Powerade can.
But convenience is an issue for athletes: If you’re in the midst of training and haven’t planned in advance, you may not have access to sports drinks. A convenient and portable option is the Nuun tablet. Nuun contains the essential electrolytes in one concentrated tablet; just drop it into your water bottle (it dissolves quickly) before drinking. Keep in mind, though, that it won’t give you an energy boost since it doesn’t replace lost calories (each tablet contains less than 8 calories).
Whatever option you chose, staying hydrated during your workout is a key part of any training regimen—particularly if you’re exercising in the heat of the summer.