TY - JOUR

T1 - No additive effect of acetaminophen when co-ingested with caffeine on cycling performance in well-trained young men

AU - Jessen, Søren

AU - Eibye, Kasper

AU - Christensen, Peter Møller

AU - Hostrup, Morten

AU - Bangsbo, Jens

N1 - CURIS 2021 NEXS 248

PY - 2021

Y1 - 2021

N2 - We investigated the effect of caffeine and acetaminophen on power output during a 6-min performance-test, peripheral fatigue, and muscle protein kinase A (PKA) substrate-phosphorylation. Fourteen men (age(mean±SD): 26±6 years; V̇O2max: 63.9±5.0 mL∙min-1∙kg-1) completed four randomized trials with acetaminophen (1500 mg), caffeine (5 mg∙kg body wt-1), combined caffeine and acetaminophen (caffeine+acetaminophen) or placebo. Mean power output during the 6-min performance-test (placebo mean:312±41 W) was higher with caffeine (+5 W; 95% CI: 1 to 9; P = 0.017) and caffeine + acetaminophen (+6 W; 95% CI: 0 to 12; P = 0.049) than placebo, but not with acetaminophen (+1 W; 95% CI: -4 to 7; P = 0.529). Decline in quadriceps maximal isometric voluntary torque immediately after the performance test was lower (treatment × time; P = 0.035) with acetaminophen (-40 N∙m; 95% CI: -53 to -30; P < 0.001) and caffeine + acetaminophen (-44 N∙m; 95% CI: -58 to -30; P < 0.001) than placebo (-53 N∙m; 95% CI: -71 to -39; P < 0.001) but was similar with caffeine (-54 N∙m; 95% CI: -69 to -38; P < 0.001). Muscle phosphocreatine content decreased more during the performance test (treatment × time; P = 0.036) with caffeine + acetaminophen (-55 mmol∙kg dry wt-1; 95% CI: -65 to -46; P < 0.001) than placebo (-40 mmol∙kg dry wt-1; 95% CI: -52 to -24; P < 0.001). Muscle net lactate accumulation was not different from placebo (+85 mmol∙kg dry wt-1; 95% CI: 60 to 110; P < 0.001) for any treatment (treatment × time; P = 0.066), being +75 mmol∙kg dry wt-1 (95% CI: 51 to 99; P < 0.001) with caffeine, +76 mmol∙kg dry wt-1 (95% CI: 58 to 96; P < 0.001) with acetaminophen, and +103 mmol∙kg dry wt-1 (95% CI: 89 to 115; P < 0.001) with caffeine + acetaminophen. Decline in muscle ATP and glycogen content and increase in PKA substrate phosphorylation was not different between treatments (treatment × time; P > 0.1). Thus, acetaminophen provides no additive performance enhancing effect to caffeine during 6-min maximal cycling. In addition, change in PKA activity is likely not a major mechanism of performance improvement with caffeine.

AB - We investigated the effect of caffeine and acetaminophen on power output during a 6-min performance-test, peripheral fatigue, and muscle protein kinase A (PKA) substrate-phosphorylation. Fourteen men (age(mean±SD): 26±6 years; V̇O2max: 63.9±5.0 mL∙min-1∙kg-1) completed four randomized trials with acetaminophen (1500 mg), caffeine (5 mg∙kg body wt-1), combined caffeine and acetaminophen (caffeine+acetaminophen) or placebo. Mean power output during the 6-min performance-test (placebo mean:312±41 W) was higher with caffeine (+5 W; 95% CI: 1 to 9; P = 0.017) and caffeine + acetaminophen (+6 W; 95% CI: 0 to 12; P = 0.049) than placebo, but not with acetaminophen (+1 W; 95% CI: -4 to 7; P = 0.529). Decline in quadriceps maximal isometric voluntary torque immediately after the performance test was lower (treatment × time; P = 0.035) with acetaminophen (-40 N∙m; 95% CI: -53 to -30; P < 0.001) and caffeine + acetaminophen (-44 N∙m; 95% CI: -58 to -30; P < 0.001) than placebo (-53 N∙m; 95% CI: -71 to -39; P < 0.001) but was similar with caffeine (-54 N∙m; 95% CI: -69 to -38; P < 0.001). Muscle phosphocreatine content decreased more during the performance test (treatment × time; P = 0.036) with caffeine + acetaminophen (-55 mmol∙kg dry wt-1; 95% CI: -65 to -46; P < 0.001) than placebo (-40 mmol∙kg dry wt-1; 95% CI: -52 to -24; P < 0.001). Muscle net lactate accumulation was not different from placebo (+85 mmol∙kg dry wt-1; 95% CI: 60 to 110; P < 0.001) for any treatment (treatment × time; P = 0.066), being +75 mmol∙kg dry wt-1 (95% CI: 51 to 99; P < 0.001) with caffeine, +76 mmol∙kg dry wt-1 (95% CI: 58 to 96; P < 0.001) with acetaminophen, and +103 mmol∙kg dry wt-1 (95% CI: 89 to 115; P < 0.001) with caffeine + acetaminophen. Decline in muscle ATP and glycogen content and increase in PKA substrate phosphorylation was not different between treatments (treatment × time; P > 0.1). Thus, acetaminophen provides no additive performance enhancing effect to caffeine during 6-min maximal cycling. In addition, change in PKA activity is likely not a major mechanism of performance improvement with caffeine.

KW - Faculty of Science

KW - Supplement

KW - Paracetamol

KW - Athletes

KW - Muscle metabolism

KW - Doping

U2 - 10.1152/japplphysiol.00108.2021

DO - 10.1152/japplphysiol.00108.2021

M3 - Journal article

C2 - 34013747

VL - 131

SP - 238

EP - 249

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 1

ER -