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Placebo effects of caffeine on maximal voluntary concentric force of the knee flexors and extensors
Author(s) -
Tallis Jason,
Muhammad Bilal,
Islam Mohammed,
Duncan Michael J.
Publication year - 2016
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.25060
Subject(s) - caffeine , placebo , concentric , expectancy theory , psychology , physical therapy , physical medicine and rehabilitation , anesthesia , medicine , social psychology , alternative medicine , geometry , mathematics , pathology
: We examined the placebo effect of caffeine and the combined effect of caffeine and caffeine expectancy on maximal voluntary strength. Methods : 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. Results : 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. Conclusion : 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