Athletes are becoming more aware that nutritional needs play a pivotal role in achieving optimal results. It is now quite common for athletes to ingest liquid carbohydrates following exercise to replenish glycogen stores to increase future performances capabilities. Glycogen is a reservoir of carbohydrates and is the main fuel utilized during intense exercise sessions.1
Restoring glycogen stores increases the chance that energy stores are available and is vital for muscle recovery. More recently, it has suggested that ingesting a combination of both carbohydrates and protein may be more beneficial for muscle recovery than just carbohydrates alone. A recent study compared a drink consisting of carbohydrates, protein, and ribose to that of a carbohydrate-only drink, and the effects each had on endurance training.2
The study lasted a period of 8 weeks, and consisted of thirty-two healthy men. Each participant performed tests for aerobic capacity (Vo2peak), time-to-exhaustion (TTE) at 90% Vo2peak, body fat percentage, and fat-free mass. Cycle ergometry training was performed at 70% VO2peak, for 1 hour a day, 5 days a week. These assessments were performed at pre-testing, mid-testing (3 weeks), mid-testing (6 weeks), and post testing.3
Each participant was given either a control drink which consisted of 93 grams of carbohydrates, or a test drink which consisted of 14 grams of protein, 76 grams of carbohydrates, and 2.2 grams of d-ribose. Each drink had the same caloric content, volume, taste, and color, and was to be ingested immediately following training.3
Although the test drink group indicated better results, there was not a substantial difference between the control and test drink groups across the board. Both groups saw a significant increase in VO2peak and total time to exhaustion. Although the test drink did not see a decrease in bodyweight, VO2peak, or time-to-exhaustion much more than the carb-only drink, it did distinctly improve body fat percentage and fat free mass within the first three to six weeks of supplementation. The carb-only repletion drink had little to no effect on body fat percentage or fat free mass.4
Based on this study, and with the thought that glycogen repletion is important for increasing performance, there may be little added benefit to adding protein to the carbohydrate drink to improve endurance performance. This is contrary to popular belief that a protein source is also needed for optimal recovery, but it should be emphasized the study did not test different training protocols such as those that rely on strength and speed, which require a different form of muscular involvement.5