Acetaminophen ingestion improves muscle activation and performance during a 3-min all-out cycling test

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.

Caffeine but not acetaminophen increases 4-km cycling time-trial performance

“…Based on previous findings [7,9], the acetaminophen ingestion was expected to improve exercise performance. This non-improvement in exercise performance after acetaminophen ingestion in the present study conflicts with previous observations that acetaminophen ingestion (1.5 g) improves exercise performance during a 16.1-km cycling TT [9], increases total work done during a 3-min all-out test [36], increases time to task failure at 70% V̇O 2 max (8), raises the peak or mean power output during repeated sprints [7,19], and increases mean torque during a 60 x 3-s MVC (2-s passive recovery period) protocol [37]. On the other hand, other studies failed to find an effect of acetaminophen ingestion on time to task failure at 70% V̇O 2 max [17] or repeated sprint performance [18].…”

Acute ibuprofen ingestion does not attenuate fatigue during maximal intermittent knee extensor or all-out cycling exercise

“…Both protocols (part A and B) followed identical experimental designs to previous research conducted within our laboratory (Morgan et al 2018a(Morgan et al , 2018b. For part A (Morgan et al 2018a), participants visited the laboratory on three occasions over a 3-4 week period with tests being conducted on an isokinetic dynamometer (Biodex System 3, Shirley, NY, USA).…”

“…Indeed, when the ascending projection of group III and IV muscle afferents is attenuated via intrathecal fentanyl administration, central motor drive is increased (as inferred via electromyography, EMG) and peripheral fatigue development is expedited (Amann et al 2009(Amann et al , 2011Blain et al 2016). Therefore, it is possible that an intervention that is able to 4 reduce the magnitude of afferent feedback, such as NSAID administration, may attenuate the decline in skeletal muscle activation during intense exercise and thus improve exercise performance (Amann & Calbet, 2008;Morgan et al 2018a;Morgan et al 2018b). Indeed, elevating the magnitude of muscle afferent feedback is known to impair endurance exercise capacity (i.e.…”

“…Acute consumption of analgesics (e.g. acetaminophen, ACT) has been shown to improve exercise performance (Foster et al 2014;Mauger et al 2010;Morgan et al 2018a;Morgan et al 2018b). Mauger et al (2010) administered an acute dose of 1.5 g ACT to trained cyclists and reported a 2% improvement in 16.1-km time-trial (TT) performance.…”

“…Mauger et al (2010) administered an acute dose of 1.5 g ACT to trained cyclists and reported a 2% improvement in 16.1-km time-trial (TT) performance. Moreover, an acute dose of ACT has been shown to improve exercise tolerance in the heat (Mauger et al 2014), repeated sprint performance (Foster et al 2014), repeated maximal voluntary contraction (MVC) performance of the knee extensors (Morgan et al 2018a) and maximal cycling performance (Morgan et al 2018b). However, while these studies suggest that oral administration of a commercially-available pharmaceutical analgesic can delay fatigue development and improve exercise performance (Foster et al 2014;Mauger et al 2010;Morgan et al 2018a, b), the ergogenic effects of IBP are unclear despite widespread use of IBP as a putative performance aid (Cleak, & Eston.…”