Purpose:To assess the effects of acute combined L-carnosine and β-alanine (Carn-BA) supplementation on isometric and dynamic tasks.Methods:Twelve healthy participants performed knee-extensor maximal voluntary contractions (MVCs) and countermovement jumps (CMJs) before and after a fatiguing protocol (45-s continuous CMJs). Isometric and dynamic tests were performed 4 h after ingestion of Carn-BA (2 g of L-carnosine and 2 g of β-alanine) or placebo (PLA), in random order. After the fatiguing protocol, blood lactate concentration ([La⁻]), general and muscular rating of perceived exertion (RPE), and muscle pain (24 and 48 h after the end of the fatiguing protocol) were assessed.Results:During the fatiguing protocol, significant decreases in jump height and increases in contact time were found in both groups from the 15th second onward to the end of the fatiguing protocol. Average contact time and jump height were respectively lower (−7%; P = .018) and higher (+6%; P = .025) in Carn-BA than in PLA. After the fatiguing protocol, MVC decreased in both PLA and Carn-BA, but it was higher in Carn-BA than in PLA (+15%, P = 0.012), while CMJ did not change. Moreover, general RPE was lower and muscle pain at 24 h was higher in Carn-BA than in PLA, whereas muscle RPE and [La⁻] did not differ between conditions.Conclusions:Ingesting Carn-BA before exercise induced positive effects on MVC and CMJ after the fatiguing protocol and improved CMJ performance during the 45-s continuous jumping effort, even when acutely supplemented. Furthermore, Carn-BA reduced the general RPE and increased muscle pain 24 h after the fatiguing task.