Abstract
<title>Abstract</title> <p> The acute effects of caffeine on sport-specific skills requiring precise force control have sometimes been examined. However, the mechanisms by which caffeine may influence such multi-component skills are rarely discussed. This study focused on force output accuracy in a simple incremental force output task to examine the acute effects of caffeine. In a randomized, double-blind, crossover trial, 13 young healthy males performed an incremental contraction test after ingesting 6 mg/kg caffeine or placebo. Force output variability was quantified as the absolute difference between actual force output and a linearly increasing target force from 0 to 50% maximal voluntary isometric torque. Time-course analyses revealed that caffeine significantly increased absolute differences in force output at ≤ 4700 ms ( <italic>i.e.</italic> , ≤ 13.8% maximal voluntary isometric torque) compared with a placebo. These results suggest that caffeine may acutely impair fine force control during low-level contractions, potentially compromising skill performance requiring fine control of low-level contractions in terms of force output accuracy. </p>