Effects of β-alanine supplementation on kickboxing-specific anaerobic performance, neuromuscular power, and strength endurance: A randomized, double-blind, placebo-controlled trial

Abstract

β-Alanine (BA) elevates skeletal muscle carnosine and may improve repeated high-intensity performance; however, evidence in kickboxing is limited. This study investigated the effects of 4-week BA supplementation on sport-specific kickboxing anaerobic performance, neuromuscular power, and strength endurance in trained male kickboxers. Twenty-eight athletes were randomly assigned to BA (6.4 g·day-1; n=14) or placebo (n=14) in a double-blind, placebo-controlled design. Pre- and post-intervention assessments included the Kickboxing Anaerobic Speed Test (KAST1–5, KASTbest, KASTtotal, Performance Decrement Index [PDI]), neuromuscular power (countermovement jump [CMJ], squat jump [SJ]), and strength endurance tests (push-up, pull-up). Baseline differences were tested via t-tests, effect sizes calculated according to Hedges’ g formula. Group×time effects were analyzed using two-way repeated-measures ANOVA with partial eta squared (ηp2) effect sizes. Baseline measures were comparable (all p>0.05). After supplementation, no significant group×time interactions emerged for CMJ (p=0.148), SJ (p=0.717), KAST1–5 (all p>0.05), KASTbest (p=0.071), or PDI (p=0.454). However significant improvements were observed in the BA group for KASTtotal (F(1,26)=14.49, p<0.001, ηp2=0.358), push-ups (F(1,26)=5.89, p=0.023, ηp2=0.185), and pull-ups (F(1,26)=9.79, p=0.004, ηp2=0.274). Four weeks of BA supplementation enhanced total anaerobic performance (KASTtotal) and upper-body strength endurance (push-up, pull-up), while no significant changes were observed in neuromuscular jump performance (CMJ, SJ). BA appears to be a practical ergogenic aid for improving repeated-effort and strength-endurance capacity in kickboxing.