By Kara Maloney, M.S., R.D., L.D.N.
There are many sports drinks on the market today, but are they better for you than plain water to keep you well-hydrated when you exercise?
Sports drinks provide small amounts of various sugars which our bodies can use while exercising. They also improve hydration because they contain electrolytes (sodium, potassium and chloride), which we can lose as we sweat during exercise.
Sports drinks were developed to aid athletes who were practicing for extended periods of time in the Florida heat. They were not designed for the recreational athlete or spectator.
Sports drinks may help athletes stay well-hydrated, replenish electrolytes lost through sweat and boost energy levels by replenishing glycogen stores during longer, more intense exercise. This can improve endurance and enhance performance by preventing the depletion of glycogen in the muscles and liver, which is the #1 cause of fatigue. Glucose is the primary fuel for the working muscles at high intensities. During exercise, our bodies utilize glucose from recent meals we have eaten or mobilize glycogen stores to fuel the working muscles. The longer the exercise continues past one hour, the more likely it is that blood glucose will be used to help supply energy for the working muscles.
If you're exercising for less than an hour, water is sufficient. If you're exercising for longer than that at a moderate to high intensity, you may want to consider a sports drink. Sports drinks have no purpose if you are sitting watching a game or consuming with a snack or meal. Ounce for ounce, they contain about half the calories and sugar of fruit juice or regular soda and can quickly add calories to your diet.
Look for one that contains 6% to 8% carbohydrate. The higher the carbohydrate content, the slower the rate of gastric emptying or speed at which food and fluids leave the stomach. Sports drinks that contain more than 8% carbohydrate may cause nausea, cramping and diarrhea.
If you're not training for a marathon or exercising in the Florida heat for an extended period of time, sports drinks may just be contributing excess calories to your diet. This can lead to weight gain.
Water is still the best sports drink for those recreational athletes who are exercising less than an hour on most days. It's inexpensive, readily available and doesn't contain calories. If you prefer a little flavor, look for "fitness waters," such as Propel that provide the necessary fluid for proper hydration along with some taste but fewer calories (10 calories per 8 ounces).
These guidelines from the American College of Sports Medicine will help keep you well-hydrated during exercise:
Kara Maloney, M.S., R.D., L.D.N. is a Clinical Dietitian at Brigham and Women's Hospital.