title: Placebo effects of caffeine on maximal voluntary concentric force of the knee flexors and extensors.
abstract: We examined the placebo effect of caffeine and the combined effect of caffeine and caffeine expectancy on maximal voluntary strength.
  
  
  
  Fourteen men completed 4 randomized, single-blind experimental trials: (1) told caffeine, given caffeine (5 mg/kg) (CC); (2) told caffeine, given placebo (CP); (3) told placebo, given placebo (PP); and (4) told placebo, given caffeine (PC). Maximal voluntary concentric force and fatigue resistance of the knee flexors and extensors were measured using isokinetic dynamometry.
  
  
  
  A significant and equal improvement in peak concentric force was found in the CC and PC trials. Despite participants believing caffeine would evoke a performance benefit, there was no effect of CP.
  
  
  
  Caffeine caused an improvement in some aspects of muscle strength, but there was no additional effect of expectancy. Performance was poorer in participants who believed caffeine would have the greatest benefit, which highlights a link between expected ergogenicity, motivation, and personality characteristics. Muscle Nerve 54: 479-486, 2016.
authors.affiliation: School of Life Sciences, James Starley Building, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Tallis
authors.affiliation: School of Life Sciences, James Starley Building, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
authors.forename: Bilal
authors.initials: B
authors.lastname: Muhammad
authors.affiliation: School of Life Sciences, James Starley Building, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Islam
authors.affiliation: School of Life Sciences, James Starley Building, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Duncan
mesh_terms: D000704:Analysis of Variance; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D006801:Humans; D007719:Knee Joint / Q000187:drug effects*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000187:drug effects*; D010465:Perception; D015990:Placebo Effect; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine
keywords: caffeine; deception; ergogenic aids; isokinetic dynamometry; placebo; strength