Do you need water or a sports drink during physical activity?

Blog Post

Stephen W. Farrell, PhD, FACSM
The Cooper Team
Fit Tips
June 17, 2021

The human body is approximately 60% water by weight. Water is the nutrient that is most often neglected by those who are highly physically active. Research has shown time and time again that as little as a 2% loss of body weight through sweating can have a significant effect on athletic performance. This is equivalent to a 180-pound person losing about 3.5 pounds of water.

You may be surprised to learn that it’s not uncommon for sweat losses to exceed 4 pounds per hour during heavy physical activity in hot weather. Dehydration cannot only impair physical performance, but can also lead to very serious health consequences (e.g. heat stroke). When we sweat, we lose mostly water, sodium, and potassium. These latter two substances are known as electrolytes (salts). Besides dehydration, another important factor that can impair physical performance is depletion of the body’s carbohydrate stores; as carbohydrate represents a very important fuel source for all cells, including muscle.

Should people use a sports drink or just consume plain water during physical activity?

So, it’s easy to see that dehydration can rapidly occur when people don’t drink enough fluids; especially during prolonged hot weather activity. With that as a background, a very important question comes to mind. Should people use a sports drink or just consume plain water during physical activity? The answer is that it really depends on the situation. Although there are several different brands, most sports drinks contain three basic ingredients; water, simple sugar, and the previously mentioned electrolytes sodium and potassium. It’s very important to note that sports drinks are different from energy drinks.

Briefly, energy drinks contain moderate to high amounts of caffeine, while sports drinks do not. While all sports drinks contain varying amounts of sugar, not all energy drinks contain sugar. If you are wondering about the purpose of sugar in a sports drink, it’s there to help replace carbohydrate that is being used by the working muscles, and to help prevent blood glucose (blood sugar) levels from falling. We’ve known for a long time that depletion of the body’s carbohydrate stores can have a detrimental effect on performance. Over the past half-century, there have been hundreds of published studies regarding the effects of sports drinks versus water on athletic performance. The overwhelming consensus from these studies is that sports drinks provide a significant advantage over water during moderate to vigorous activities lasting longer than an hour or so, particularly if the activity is being conducted in hot weather. So, let’s say that you were going to participate in a 50-mile bike ride on a hot day. There’s no question that you would be better off consuming a sports drink rather than just plain water. On the other hand, if you are out walking the dog for 15 minutes on a hot day, then water would be just fine. You may also not need those extra calories, particularly if you are overweight!

Sports drinks are a lot like running shoes. Let’s explain that seemingly strange statement. Did you know that a substantial percentage of running shoes sold in the U.S. never go for a run? It’s true! Did you know that a substantial percentage of the sports drinks sold in the U.S. are consumed by people who are sedentary or just minimally physically active? Also true! When the general public sees athletes consuming sports drinks, many of them make the assumption that sports drinks must be good for you. There’s no question that a sports drink will provide a benefit for the athlete or highly physically active person who is losing substantial amounts of fluids and electrolytes and using up carbohydrate stores during their activity. On the other hand, that same sports drink might not be so good for a person who is consuming the sports drink while sitting on their couch watching a game.    

Current guidelines for fluid replacement during exercise from the American College of Sports Medicine are as follows: Consume 6-12 ounces of fluid during every 15-20 minutes of exercise, more during hot weather.

Examples of Situations Where a Sports Drink is Very Likely to Provide a Benefit (especially on a hot day)

  • Half or full marathon
  • Triathlon
  • Long training run or bike ride
  • Sports practice session of long duration
  • Football game
  • Soccer, hockey, or basketball tournament where the team is playing multiple games on the same day
  • Hiking for more than an hour or so
  • Roofing and other forms of manual labor                                                                  

Examples of Other Situations Where a Sports Drink is Probably Unnecessary

  • Jumping to conclusions        
  • Marching to the beat of a different drummer
  • Taking a leap of faith
  • Pushing your luck
  • Side-stepping your responsibilities

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