Sports drinks of little use for recreational runners
Recreational runners who run for 45 to 90 minutes a couple of times a week can save money by not buying sports drinks. These won't help them to improve their time over twenty kilometres, write nutritionists at the University of Tennessee Knoxville in the Journal of the International Society of Sports Nutrition.
Masses of studies suggest that sports drinks help improve endurance athletes' performance. Top of the list are products containing fast carbohydrates and protein in a 3:1 ratio. These are promoted as not only providing energy but also helping muscle recovery.
But the overwhelming majority of these studies take place under lab conditions. The researchers in Tennessee therefore decided to test sports drinks on twelve trained recreational runners – men aged between 18 and 55 – who had to run a 19.2k course round a lake in the open air.
Five minutes before starting the men were given 120 ml of a sports drink and after every 4 km they were given the same amount again. So in total the men consumed 600 ml sports drink.
A light zero-calorie product. Used as a placebo. [PLA]
Sports drink containing 6% quickly absorbed carbohydrates. 25 kcal per intake. [CHO]
Sports drink containing 6% quickly absorbed carbohydrates plus 1.4% protein. 40 kcal per intake. [CHO-P]
The researchers got the men to run four times, and each time they gave them a different sports drink.
Because Gatorade provided fewer calories than Accelerade, the researchers got their test subjects to run another time and gave them a stronger concentration of Gatorade. This provided the runners with the same amount of energy as the Accelerade. [CHO-CHO]
The sports drinks had no effect on the total time the men took to run the 19.2k course, as is shown in the first figure below. It made no difference whether the sports drinks contained only carbs, a mix of carbs and proteins – they had the same effect as a zero-calorie drink.
The researchers also asked the men to do a final sprint for the last 1.92 km. The sports drinks had no influence on the men's sprint times either, as the second figure below shows.
The sports drinks had no effect on the men's heart rate or their fatigue level either.
"Results of the present investigation suggests no difference in endurance performance between commercially available CHO and CHO-P supplements in outdoor runs > 60 minutes at moderate- to vigorous-intensity for male recreational runners", the researchers write. "Additionally, this supplementation did not enhance performance above that of PLA."
J Int Soc Sports Nutr. 2013 Mar 28;10(1):17.
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