Effect of different sports drink compositions on endurance performance and substrate oxidation: a randomized, double-blind, placebo-controlled crossover study in trained athletes

Abstract

Background: The consumption of sports drinks before, during, and after endurance exercise is a common practice among athletes. These drinks typically contain a variety of components, each of which has been shown to offer individual benefits. However, the combined effects of these components, as formulated in many sports drinks, have not been thoroughly investigated. This study aims to evaluate the impact of typical sports drink components on endurance performance, perceived exertion, and carbohydrate and fat metabolism, using a sequential additive design. Methods: Twelve healthy, trained endurance athletes aged 20 to 35 years participated in a randomized, double-blind, placebo- controlled study. The study involved a baseline assessment and four exercise protocols, each separated by a 7-day washout period. During each exercise protocol, participants cycled for 40 minutes at 80% of their previously determined peak oxygen uptake , followed by an incremental protocol performed to voluntary exhaustion. Participants were randomly assigned to ingest one of four 300 ml solutions 60 and 30 minutes before each exercise protocol: solution A (placebo mineral water), solution B (dextrose and sodium), solu- tion C (solution B + beetroot extract), or solution D (solution C + arginine and L-citrulline). Ventilation and heart rate were continu- ously monitored before and throughout the exercise. Lactate and glucose levels were measured at specific time points before and during the exercise, while ratings of perceived exertion were recorded every 10 minutes. Power output was continuously tracked throughout the exercise protocol. Body weight was assessed both before and after each exercise session. Results: There were no significant differences between the four solu- tions in terms of time to exhaustion (p = .703), power output (p = .822), peak oxygen uptake (p = 990), maximum lactate concentration (p = .720), and maximum heart rate (p = .884). During the exercise, no significant differences were observed in lactate and glucose concentrations, heart rate, or ventilatory parameters (ps > .050). However, significant differences (p < .001) in blood glucose con- centrations were noted at rest and during the warm-up phase. Conclusions: The effect of the tested sports drink compositions on performance during the selected exercise protocol to voluntary exhaustion appears minimal. This study found no significant differ- ences between the solutions and the placebo. Thus, it can be concluded that consuming a dextrose-based solution before exer- cise did not offer any performance advantage over water. The additional substances included in solutions B, C, and D did not influence performance, carbohydrate metabolism, or fat metabo- lism during the exercise.