Chocolate MIlk for Recovery
We examined the possibility of milk as a recovery aid last year and this year we are going to look at more recent research from Gilson and colleagues (2010). This study used chocolate milk as a recovery beverage following a period of increased training duration (ITD) as compared to a carbohydrate rich drink. They found that milk decreased post exercise levels of creatine kinase (CK)*.
*Creatine Kinase is a chemical that is produced as a result of muscle damage. By examining the levels of CK in the blood, referred to as serum CK or plasma CK. The amount of CK present in the blood after exercise is related to the exercise intensity and duration (load). CK levels are also related to recovery the faster the recovery after exercise the faster CK levels drop. Usually the levels of CK are related to other indicators such as muscle soreness, feelings of fatigue and other indicators of fatigue and recovery are all related to CK levels in the blood. Therefore CK levels in the blood give an objective means to measure tissue damage and recovery from exercise.
The subjects were American collegiate football (soccer) players (NCAA Div I). It is accepted that this population fits the criteria of trained athletes, though not elite.
In this study subjects completed one week of baseline training followed by four days of increased duration training (ITD) after each ITD training session the subjects received either a high-carbohydrate drink or chocolate milk both of which contained exactly the same number of calories. Serum CK, myoglobin, muscle soreness, fatigue ratings and isometric (force produced but no change in muscle length) quadriceps strength were assessed and performance tests (T-Test and vertical jump) were also performed. The drinks were administered randomly and a cross over design was used where subjects repeated the protocol using the other recovery beverage following a two-week washout period. The high carbohydrate drink was flavoured with a chocolate carbohydrate gel to give a similar appearance and taste as the chocolate milk and a lab technician not directly involved in the study assigned the different drinks. Anecdotally the subjects were aware that there was a difference in taste but had no preconceived notions about the content or the likely effect of the different drinks.
When recovering using chocolate milk most indicators were the same as for the group using the high carbohydrate drink. However CK levels in the chocolate milk group were lower. While no differences were shown in the performance tests it is of the opinion of ASC that the ‚Äúin-training‚ÄĚ test protocol used for assessment was not ideal and a separate test day should have been programmed when the athletes were rested this may have shown differences between the groups. The drinking of chocolate milk through this study is shown to have similar effects to consuming high carbohydrate drinks post exercise with the addition of decreasing CK levels. This result supports other studies that show that chocolate milk is a good way to recover; these results have often been more convincing. Karp and colleagues (2006) showed that enurance cyclists could ride for longer periods on chocolate milk when compared with other recovery beverages. Thomas and others (2009) showed that chocolate milk was significantly better at improving time to exhaustion in elite cyclists than other recovery beverages one of which was a carbohydrate and protein mixture.
While so far the mechanism as to why chocolate milk should be better at recovering athletes and maintaining performance than other sports drinks is unclear. As drinking chocolate milk can do no harm pre and post exercise ASC strongly encourages all athletes to do so especially as it is a cheap and easily accessible source of nutrition.
The full text for this article and references can be found at:http://www.jissn.com/content/7/1/19
Gilson, S. F., Saunders, M. J., Moran, C. W., Moore, R. W., Womack, C. J. & Todd, M, K. (2010). Effects of chocolate milk consumption on markers of muscle recovery following soccer training: a randomized crossover study.Journal of the International Society of Sports Nutrition. 7:19. DOI:10.1186/1550-2783-7-19.
Karp, J. R., Johnston, J. D., Tecklenburg, J., Mickelborough, T. D., Fly, A.D. & Stager, J. M. (2006). Chocolate Milk as a post exercise recovery aid.International Journal of Sports Nutrition & Exercise Metabolism, 16: 78-91.
Thomas, K., Morris, P. & Stevenson, E. (2009). Improved endurance capacity following chocolate milk consumption compared with two commercially available sports drinks.Applied Physiology Nutrition & Metabolism, 34: 78-82.