Recovery Beverages - A Review of Two Recent Studies.
Stella Lucia Volpe, Ph.D., R.D., L.D.N., FACSM, is an associate professor and the Miriam Stirl Term Endowed Chair in Nutrition in the Division of Biobehavioral and Health Sciences at the University of Pennsylvania, Philadelphia, PA. She is a member of the Gatorade Sports Nutrition Board. Her degrees are both in Nutrition and Exercise Physiology, and she also is ACSM Exercise Specialist® certified. Dr. Volpe's research focuses on obesity and diabetes prevention using traditional interventions and mineral supplementation and, more recently, by altering the environment to result in greater physical activity and healthy eating. Dr. Volpe is an associate editor of ACSM's Health & Fitness Journal®.
Recovery nutrition has been a hot topic within the last 5 years, and rightly so; recovery nutrition is equally as important as preexercise nutrition and training. Although I discussed recovery nutrition in May/June, volume 11(3), 2007 issue, I will focus on recovery beverages in this issue. In particular, there are two recent studies I will discuss in this article.
CHOCOLATE MILK AS A RECOVERY DRINK
Jason R. Karp, M.S., et al (1) studied the effects of chocolate milk on recovery. The purpose of their study was to "test the efficacy of chocolate milk as a recovery drink following glycogen-depleting exercise." They determined this by assessing time to exhaustion and total power output. They compared low-fat chocolate milk to a fluid replacement drink and a carbohydrate replacement drink.
There were nine healthy trained cyclists who participated in this crossover designed study, which means that each subject went through all the treatments (in this case, they consumed each of the beverages for each trial). A crossover design is a good design because that means that each subject acts as his or her own control. They had an average maximal oxygen consumption (V˙O2max) of 65± 9 mL/kg/min. Each cyclist participated in four testing sessions. The first session consisted of incremental exercise to determine their V˙O2max and maximum power output (Pmax). The remaining three testing trials consisted of a randomized crossover design where the subjects cycled to "glycogen depletion," which was followed by a 4-hour recovery period. Participants consumed one of the three drinks during recovery time after each session immediately, postexercise, and 2 hours into the recovery period. Although the participants could not be blinded by the taste of each drink, the investigators were blinded to each trial. After consumption of the drink and the 4-hour recovery period, participants performed the second exercise bout at 70%of their V˙O2max until exhaustion. Each testing session was separated by 1 week. The investigators also collected 3-day dietary records before each testing session.
The participants' diets did not differ before each session, with respect to carbohydrate, protein, and fat intake. Karp et al (1) reported a significantly greater time to exhaustion (minutes) and a significantly greater total work (kilojoules) in the chocolate milk and fluid replacement drink trials as compared with the carbohydrate replacement drink R4 trial. Although this study showed some interesting results, some limitations to consider are the following: its small sample size (although it was a crossover design, which strengthens the results); the participants were all men, women may respond differently; they were all trained cyclists, other athletes may respond differently; the participants began each session after a 10- to 12-hour fast; glycogen stores were not directly measured (although the authors stated that the participants exercised until "glycogen depletion;" and the carbohydrate, protein, fat, energy, and electrolyte concentrations were not equal among beverages) (Table 1).
Despite these limitations, this study helped to demonstrate that chocolate milk and fluid replacement drinks were both effective as postexercise recovery beverages. Because many athletes have a difficult time consuming foods immediately postexercise, these beverages can help with recovery while also providing hydration.
CARBOHYDRATE, PROTEIN, AND ANTIOXIDANT INGESTION POSTEXERCISE
It has been debated whether protein and antioxidants, along with carbohydrates, will speed up recovery. Nicholas D. Luden, Ph.D., et al (2) compared the effects of 6 days of postexercise consumption of a carbohydrate beverage to a carbohydrate + protein + antioxidant beverage consumption on muscle damage (via creatine kinase levels), muscle soreness (subjective scale), and exercise performance in collegiate cross-country runners. Participants were given either 10 mL/kg of a carbohydrate (CHO) beverage or 10 mL/kg of a carbohydrate + protein + antioxidant (CPA) beverage in a crossover design study (see Table 2 for composition of both beverages). These trials were separated by a 21-day washout period. Participants were 11 male and 12 female collegiate cross-country runners (approximately 19 years). They each followed the same 6-day training cycle and performed in a 5- to 8-km cross-country race on day 7.
The researchers found that plasma creatine kinase levels were significantly lower after the CPA trial compared with the CHO trial. The participants also reported that they felt less muscle soreness during the CPA trial. Nonetheless, there were no differences in performance in the cross-country race between treatments. This study also had some limitations, including a small sample size (although larger than the previously described study, and this, too, was a crossover design, all participants served as their own control) and the fact that the beverages were not isoenergetic. Despite a lack of improvement in exercise performance, this study shows some promise for including some protein and antioxidants in recovery nutrition.
Both of these studies lend further credence to the importance of postexercise beverage consumption. They each provided unique ideas of what athletes can consume postexercise to improve recovery and, hence, performance. Karp et al (1) demonstrated the ability for athletes to use a common and inexpensive food (e.g., chocolate milk and, in this case, Gatorade) to aid in recovery. Dr. Luden et al (2) showed that adding protein and antioxidants to a carbohydrate beverage could help to decrease muscle soreness (both objectively and subjectively), which also could help with recovery. Athletes should be made aware of the different and inexpensive options that are available to help them with recovery nutrition, in particular, with respect to beverage consumption. After all, one of the major keys to exercise performance is nutrition!
1. Karp, J.R., J.D. Johnston, S. Tecklenburg, et al. Chocolate milk as a post-exercise recovery aid. International Journal of Sport Nutrition and Exercise Metabolism
2. Luden, N.D., M.J. Saunders, M.K. Todd. Postexercise carbohydrate-protein-antioxidant ingestion decreases plasma creatine kinase and muscle soreness. International Journal of Sport Nutrition and Exercise Metabolism