Pre-exercise Fueling and Endurance: Effect of a Pre-exercise Almond-raisin Beverage versus a Commercial Sports Beverage on Performance in Trained Male Runners

Aside from genetics and training, no factor plays as important a role in exercise performance as nutrition. What athletes consume before exercise longer than 60 min influences fuel use, perceived exertion (RPE), heart rate (HR) and time-to-exhaustion (TE). Ingesting carbohydrates (CHO) before exercise can delay exhaustion over placebo, but less is known about combinations of CHO and fat on fuel use and endurance. To date, there are few studies that systematically explore nutritious, whole food products like nuts and dried fruits as pre-exercise fuel sources for endurance exercise. The purpose of this study was to compare the effects of 2 isocaloric beverages on substrate availability and endurance capacity in trained runners: almond-raisin (AR) beverage (whole food, mixed macronutrient) and a commercial sports (CE) beverage (CHO-only and electrolytes). In a randomized, crossover study, 10 trained, male runners ran to exhaustion on a treadmill at 70% V02max twice, separated by 2 weeks. After a fasting blood sample, subjects drank one of the test beverages, rested for 60 min, and began the trial run. Serial measures were collected including blood samples, respiratory exchange ratios (RER), HR and RPE in 15-30 min intervals. TE was recorded at the end of each run. Mean TE was similar between the AR and CE trials. However, a significant difference was seen in insulin concentrations during the AR compared with the CE trials throughout exercise, with a significant blunting of insulin observed during the AR trial, but not the CE trial. Free fatty acid concentrations were significantly higher in the AR trial through 60 min, though the between trials effect did not remain significant through exhaustion and recovery. Serum glucose and lactate concentrations, RER, HR, and RPE were similar between the AR and CE trials. In conclusion, the pre-exercise almond-raisin beverage showed favorable responses in insulin and free-fatty acid concentrations during exercise and a similar mean time-to-exhaustion compared with the carbohydrate-electrolyte beverage. Therefore, the AR beverage may be considered a practical alternative to commonly used commercial sports beverages for endurance exercise