Journal Title (Medline/Pubmed accepted abbreviation): J. Int. Soc. Sports Nutr.
First Page: 22
Background: Carbohydrates improve performance in endurance exercise by supplying muscle with energy. Caffeine is also an ergogenic aid that works by reducing central fatigue. Additionally, branched chain amino acids (BCAAs) control the breakdown of protein, supply fuel, and may reduce central fatigue.
Hypothesis: Athletes will perform better at an endurance task when they consume a sports beverage with carbohydrates, caffeine, and BCAAs vs. a placebo.
Subjects: males age 29.6 ± 9.2 y who a regular caffeine users (about 1-2 cups coffee/day) and endurance athletes (train 2-4 times/week, have competed in the last 3 months), n = 13
Experimental Design: randomized, double-blind, cross-over, placebo-controlled
Sports drink: 1254 kJ/L (300 Calories/L)- carbohydrates (blend of maltodextrin, glucose, fructose; 68.6 g/L) , BCAAs (4 g/L), caffeine (75 mg/L), vitamins and minerals, and other ingredients
Placebo: 50 kJ/L (12 Calories/L)- artificial sweeteners, flavoring and coloring
Procedure: About 1 week before the start of the study, the participants were familiarized with the study procedures and the VO2max was determined. The participants repeated 2 protocols with each of the 2 treatments (4 trials total), at least one week apart. They arrived to the laboratory not having eaten in the prior 2 hrs. A baseline blood sample was acquired for analysis of blood glucose and, for protocol 2 only, lactate. Then, 250 mL of the treatment drink was consumed within 15 min. For protocol 1, they ran for 2 hrs, trying to go the farthest distance possible. They consumed 250 mL of the test beverage every 15 min so that 2 L was consumed total. For protocol 2, the athletes ran at a speed of 95% their lowest average speed sustained during protocol 1. A post-workout blood sample was subsequently collected. Only in protocol 2, respiratory gases were monitored during exercise. Central and periphery fatigue were assessed before and after exercise in protocol 2.
A sports beverage with caffeine, carbohydrates, and BCAAs enhanced endurance performance compared to a beverage with very little calories. This is in part due to preservation of neuromuscular function (delaying fatigue) and providing a constant supply of available energy.