title: Effect of caffeine ingestion on maximal voluntary contraction strength in upper- and lower-body muscle groups.
abstract: The effect of caffeine on strength-power performance is equivocal, especially with regard to maximal voluntary contraction (MVC) strength. This is partly related to differences in upper- and lower-body musculature. However, there is no evidence to suggest whether this is a product of muscle group location, muscle group size, or both. Consequently, the primary aim of this study was to establish whether the effect of caffeine ingestion on MVC strength in upper- and lower-body muscle groups is significantly different, and if so, to determine whether this is a product of muscle group size. In a randomized, subject-blind crossover manner, 16 resistance-trained men (estimated caffeine intake [mean ± SD] 95.4 ± 80.0 mg·d) received either 6 mg·kg of caffeine (CAF) or a placebo (PLA). Isokinetic peak torque of the knee extensors, ankle plantar flexors, elbow flexors and wrist flexors were measured at an angular velocity of 60°·s. Statistical analyses revealed a significant increase in isokinetic peak torque from PLA to CAF (p = 0.011) and a significant difference in isokinetic peak torque between muscle groups (p < 0.001). However, there was no significant treatment × muscle group interaction (p = 0.056). Nonetheless, the %improvement in isokinetic peak torque with caffeine increased with muscle group size. In conclusion, a moderate dose of caffeine improves MVC strength in resistance-trained men regardless of muscle group location, whereas the influence of muscle group size remains uncertain. This research may be useful for competitive and recreational athletes aiming to increase strength-power performance.
authors.affiliation: Institute for Sport, Physical Education and Health Sciences, The University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Tomas D
authors.initials: TD
authors.lastname: Timmins
authors.forename: David H
authors.initials: DH
authors.lastname: Saunders
mesh_terms: D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D018592:Cross-Over Studies; D006801:Humans; D035002:Lower Extremity; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D009929:Organ Size; D016037:Single-Blind Method; D019415:Torque; D034941:Upper Extremity; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine