Optimizing endurance performance in elite swimmers: effects of L-carnitine supplementation and hydration strategies

Water quality and hydration are crucial in optimizing athletic performance, particularly for elite swimmers who train in aquatic environments. This study introduces a novel split-dose L-carnitine (LC) supplementation protocol. It examines its combined effects with hydration strategies on endurance performance in swimmers, comparing it against a standard single-dose method: a standard protocol (2 g of LC taken 60 min before exercise) and an experimental protocol (1 g of LC taken 90 and 60 min before exercise). Seven highly trained swimmers (aged 23.7 ± 2.0 years; competitive training experience: 7.0 ± 1.0 years) participated in a double-blind, placebo-controlled, crossover study. Performance assessments were conducted using a cycling ergometer test lasting 13 min, during which respiratory quotient, heart rate, and perceived exertion (Borg scale) were recorded at 1-min intervals. Results showed that the experimental protocol led to significantly lower respiratory quotient values at 4, 5, 7, 11, and 12 min, suggesting enhanced fat oxidation. The heart rate was considerably lower at 3 and 4 min, indicating improved cardiovascular efficiency. Perceived exertion was also significantly reduced from the 7th to the 13th minute under the experimental protocol. Additionally, hydration status and water intake were monitored to assess their influence on performance. These findings highlight the importance of effective supplementation and hydration strategies in enhancing endurance and reducing exertion in swimmers, contributing to sustainable water management practices for athletes in aquatic sports. This study provides insights into optimizing hydration strategies and nutrient intake to support performance and recovery, particularly in high-intensity swimming environments.