Hydration During Exercise: Sport Drink Guidelines

 The energy beverage industry is a huge market.  It can be confusing for athletes, however, who need specific formulations during exercise that can be easily tolerated and quickly pass out of the stomach and absorbed.  Here is a quick guide:

• Always use a sports drink during exercise of >1 hour duration.
• Choose a sports hydration drink that contains more than one type of sugar (maltodextrin, sucrose, fructose, glucose polymer) to insure the fastest rate of absorption of carbohydrate energy to the muscles.
• Do not use drinks that are made with pure fructose as the sole carbohydrate source (honey, fruit juice).  Fructose requires a GLUT-4 transporter to cross the intestine, and will often cause gas and cramping – or worse.
• The concentration of carbohydrate should be 6-9% for a sports hydration drink.  This can be easily calculated: 14 g carb/240 ml x 100 = 5.8%.  Drinks that are over 10% (fruit juice, soda) cannot be absorbed from the stomach rapidly.
• All sport drinks will improve the body’s ability to stay hydrated during exercise better than water alone because of added sodium.
• Using a sports drink with added protein can help minimize muscle damage during long duration exercise where glycogen stores have become depleted. 
• Aim for a minimum of 30g of supplemental carb/hour.  This can be achieved with a sports hydration drink.  In order to reach 60g of carbohydrate per hour, a combination of drink, gel, and water may be necessary.
• Fluids should include sodium and potassium, which are lost in sweat.  Ideally during events lasting over 2 hours, drink at least 8 oz every 20 minutes and use a product that supplies 200 mg sodium per 8 oz.
• Athletes can easily lose 2  grams of salt per hour when sweating at a rate of a liter per hour. In a 5 hour race, that can mean 10+grams of salt, which is equivalent to 4000 mg of sodium.   Sports drinks can provide some of that sodium, however, heavy sweaters should not rely solely on their sports drink.  Salty food sources are recommended to supplement.
• One final piece of advice?  Practice hydrating during training.  Individuals vary greatly in their sweat rates and need to individualize their fluid and electrolyte replacement schedule.  Be organized on race day with a fool proof plan.

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