Caffeine Ingestion Attenuates Fatigue-induced Loss of Muscle Torque Complexity

What this study found

Caffeine improved performance and slowed the fatigue-related deterioration in torque complexity versus placebo. Time to task failure increased from 7.2 ± 5.6 min with placebo to 9.5 ± 7.9 min with caffeine, a 2.4 ± 2.6 min gain; 95% CI 0.7 to 4.1, P = 0.019. Caffeine also slowed the decline in MVC torque (−18.2 ± 14.1 vs −23.0 ± 17.4 N·m·min−1) and the decline in voluntary activation, while peripheral fatigue did not differ between conditions. Complexity-related metrics were better preserved with caffeine, including higher approximate entropy at isotime (0.27 ± 0.12 vs −0.13 ± 0.04; 95% CI…

Study & population

This was a randomized, double-blind, crossover laboratory study in healthy adults performing intermittent isometric knee-extensor contractions to task failure.

Intervention

Caffeine was given as a single oral dose of 6 mg/kg in gelatin capsules 60 min before the fatigue trial, timed to approximate peak plasma concentration.

Key limitation

The active-arm sample was small and limited to healthy habitual caffeine consumers, which reduces generalizability.

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