A new study that found chocolate milk is as good as or better than leading sports drinks for recovery from exhausting exercise has ignited a debate regarding the best composition of sports beverages.
"Milk is a food and contains carbohydrates and protein. So why shouldn't it be a good delivery vehicle for macronutrient replacement?" said Conrad Earnest, PhD, director of the Center for Human Performance and Nutrition Research at the Cooper Institute in Dallas, Texas. He was not connected to the study.
Published in the February International Journal of Sport Nutrition and Exercise Metabolism, the study was predicated on the idea that exercising to exhaustion reduces the supply of muscle glycogen, a key source of fuel. Gatorade supplies those carbohydrates, along with electrolytes lost by sweating. Adding protein to drinks protects muscle mass and reduces exercise-induced muscle damage. This carb/protein combination is a hallmark of the recent wave of sports drinks like Endurox R4— as well as chocolate milk. Both Endurox R4 and chocolate milk have a 4:1 ratio of carbs to protein.
With this as background, researchers at the Indiana University Human Performance Lab looked at which of the three drinks improved a range of performance parameters in a small group of athletes.
There were no significant differences between the drinks in most measured parameters. However, both time to exhaustion and total work performed during the endurance performance ride were significantly greater in the chocolate milk and Gatorade groups compared to the Endurox group.
The study was funded in part by a grant from the Dairy and Nutrition Council. Some researchers found notable flaws with the findings, among them, that the nine subjects in the study were not directly assessed for muscle glycogen stores prior to, between or after each intervention. Also, the subjects' level of training was very different between subjects, which would influence their recovery from exercise bouts and their ability to utilise the different drink compositions for energy.
What's a formulator to do?
"We have established the premise that macronutrient combinations work," said Earnest. "The evolution of isolating nutrients to study has become such that we in the natural products industry seem to feel that only isolated nutrients can fulfil the function," said Earnest. "Perhaps a wiser approach is to occasionally step back and re-examine the big picture. Why not start re-examining whole foods again?"
British sports researcher Mark Tallon, PhD, however, lauded the science that continues to drill down to maximise nutrient content levels and ratios in an effort to enhance performance.
"Research has moved beyond the simplicity of playing with carbohydrate percentages and the addition of electrolytes to energy and rehydration drinks," said Tallon. "We are now in a new era of looking to the addition of caffeine and mixed carbohydrate sources — sucrose, glucose, fructose, maltose — which seem to influence multiple transport systems in the body. This allows greater absorption and oxidation of carbohydrates both during and post-exercise."