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Updated: Feb 4, 2026

Muscle Velocity Recovery Cycles to Examine Muscle Membrane Properties
Published on: February 19, 2020
Acetaminophen ingestion improves muscle activation and performance during a 3-min all-out cycling test
Paul T Morgan1,1, Anni Vanhatalo1,1, Joanna L Bowtell1,1
1Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter EX1 2LU, UK.
Abstract:
Acute acetaminophen (ACT) ingestion has been shown to enhance cycling time-trial performance. The purpose of this study was to assess whether ACT ingestion enhances muscle activation and critical power (CP) during maximal cycling exercise. Sixteen active male participants completed two 3-min all-out tests against a fixed resistance on an electronically braked cycle ergometer 60 min after ingestion of 1 g of ACT or placebo (maltodextrin, PL). CP was estimated as the mean power output over the final 30 s of the test and W' (the curvature constant of the power-duration relationship) was estimated as the work done above CP. The femoral nerve was stimulated every 30 s to measure membrane excitability (M-wave) and surface electromyography (EMGRMS) was recorded continuously to infer muscle activation. Compared with PL, ACT ingestion increased CP (ACT: 297 ± 32 W vs. PL: 288 ± 31 W, P < 0.001) and total work done (ACT: 66.4 ± 6.5 kJ vs. PL: 65.4 ± 6.4 kJ, P = 0.03) without impacting W' (ACT: 13.1 ± 2.9 kJ vs. PL: 13.6 ± 2.4 kJ, P = 0.19) or the M-wave amplitude (P = 0.66) during the 3-min all-out cycling test. Normalised EMGRMS amplitude declined throughout the 3-min protocol in both PL and ACT conditions; however, the decline in EMGRMS amplitude was attenuated in the ACT condition, such that the EMGRMS amplitude was greater in ACT compared with PL over the last 60 s of the test (P = 0.04). These findings indicate that acute ACT ingestion might increase performance and CP during maximal cycling exercise by enhancing muscle activation.
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