It is well documented that consumption of carbohydrates during exercise can improve performance (1), and there is also a wealth of research that supports the notion that including electrolytes such as sodium into a sports drink has been shown to increase and support hydration levels (ingestion rates) during and post-exercise (2).
More recently there has been research into the use of carbohydrate-protein combinations in an attempt to increase time-to-exhaustion and improve recovery when compared to a carbohydrate drink (3).
A recently published study investigated the effect of a commercially available carbohydrate-protein-electrolyte (CPE) beverage on short term repeated exercise performance; specifically submaximal and time-trial performance.
Sixteen recreationally trained males performed two exercise trials separated by 7 days. Trials consisted of two bouts of 90 minutes exercise separated by 2 hours of recovery.
Bouts involved 45 minutes on a cycle-ergometer (60% VO2 max (ST)), followed immediately by a 45 minute performance test (PT). Random assignment put participants in either 8% CPE beverage, or a colour/taste matched placebo group (PL). Participants consumed 100ml of their assigned drink every 10 minutes during each ST, and 500ml at 0 and 60 minutes into recovery.
Mean power output (W), speed (km.hr1) and distance covered (km) were assessed throughout both trials. Expired air was sampled at 10 minute intervals throughout ST. Blood glucose and lactate were assessed during ST and recovery.
Distance covered during ST was significantly reduced with PL by 9.12%. With CPE, distance covered, power output and average speed were maintained between ST1 and ST2. Mean blood glucose was maintained in CPE across ST trials, and was significantly greater than PL in ST2. Mean distance during PT2 was 2.96 km (or 17.1%) further with CPE than PL.
Consumption of a CPE drink improves short-term repeated exercise and subsequent performance when compared to PL. Improvements in carbohydrate oxidation, maintenance of plasma glucose and lower levels of fatigue look to be beneficial for secondary bouts of performance and a quicker rate of recovery.
It can be clearly seen from this study that consumption of a carbohydrate-protein-electrolyte drink improves overall endurance exercise performance when compared to a placebo. However, to further investigate the effectiveness of the CPE drink, the optimal concentration of carbohydrate and protein within the drink needs to be assessed. This means trialling different ingredient ratios to identify any variation in outcomes.
There is also now the need for a direct comparison to be made between a carbohydrate-electrolyte and a CPE drink, and to measure an extensive range of outcomes.
These results do indicate that a CPE drink may be beneficial when recovery between bouts of exercise is relatively short and/or glycogen depletion may significantly increase levels of fatigue. Therefore, this encompasses a huge number of physical activities that could benefit from this type of sports drink. It could be prove to be highly beneficial to the large number of regular gym goes who have little rest between exercises.
For those of you looking for a carbohydrate/protein shake, the following come highly recommended:
Author: David Rowse
1. Coggan AR, Coyle EF: Reversal of fatigue during prolonged exercise by carbohydrate infusion or ingestion. J Appl Physiol 1987, 63(6):2388–2395.
2. Shirreffs SM, Taylor AJ, Leiper JB, Maughan RJ: Post-exercise rehydration in man: Effects of volume consumed and drink sodium content. Med Sci Sports Exerc 1996, 28:1260–1271.
3. Ivy JL, Res PT, Sprague RC, Widzer MO: Effect of a carbohydrate-protein supplement on endurance performance during exercise of varying intensity. Int J Sports Nutr Exerc Metabol 2003, 13(3):383–395.
© 2012, David Rowse. All rights reserved.