Influence of fitness status on high-intensity intermittent performance in response to fruit-derived polyphenol supplementation

Objective: This study examined the effects of cocoa flavanol (CFL) supplementation on high-intensity intermittent performance and aerobic capacity, focusing on the role of fitness status. Methodology: Forty-four male participants, divided into trained (n = 22) and non-trained (n = 22) groups, completed the Yo-Yo Intermittent Recovery Test Level 1 (YYIRTL1) after seven days of CFL or placebo supplementation. The study employed a double-blind, randomized cross-over design. Results: Results showed that CFL supplementation significantly improved performance in both groups, with the trained group demonstrating a greater increase in total distance covered during YYIRTL1 compared to placebo (mean difference: 1169 m, P < 0.01). Additionally, VO2max significantly improved in the trained group (mean difference: 9.82 mL·kg⁻¹·min⁻¹, P < 0.01). In the non-trained group, CFL supplementation also led to significant enhancements in YYIRTL1 performance (mean difference: 438.2 m, P < 0.01) and VO2max (mean difference: 4.76 mL·kg⁻¹·min⁻¹, P < 0.01), although the improvements were less pronounced than in the trained group. These findings indicate that CFL supplementation effectively boosts performance and aerobic capacity, with more substantial benefits observed in trained individuals. Further studies are needed to investigate long-term effects and the mechanisms underlying differential responses based on fitness level.