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Med Sci Sports Exerc. 2013 Nov;45(11):2184-92. doi: 10.1249/MSS.0b013e31829a6672.

Neuromuscular responses to incremental caffeine doses: performance and side effects.

Author information

1
1Exercise Physiology Laboratory at Toledo, University of Castilla-La Mancha, Toledo, SPAIN; and 2Spanish Anti-doping Agency, Doping Control Laboratory in Madrid, SPAIN.

Abstract

PURPOSE:

The purpose of this study was to determine the oral dose of caffeine needed to increase muscle force and power output during all-out single multijoint movements.

METHODS:

Thirteen resistance-trained men underwent a battery of muscle strength and power tests in a randomized, double-blind, crossover design, under four different conditions: (a) placebo ingestion (PLAC) or with caffeine ingestion at doses of (b) 3 mg · kg(-1) body weight (CAFF 3mg), (c) 6 mg · kg(-1) (CAFF 6mg), and (d) 9 mg · kg(-1) (CAFF 9mg). The muscle strength and power tests consisted in the measurement of bar displacement velocity and muscle power output during free-weight full-squat (SQ) and bench press (BP) exercises against four incremental loads (25%, 50%, 75%, and 90% one-repetition maximum [1RM]). Cycling peak power output was measured using a 4-s inertial load test. Caffeine side effects were evaluated at the end of each trial and 24 h later.

RESULTS:

Mean propulsive velocity at light loads (25%-50% 1RM) increased significantly above PLAC for all caffeine doses (5.4%-8.5%, P = 0.039-0.003). At the medium load (75% 1RM), CAFF 3mg did not improve SQ or BP muscle power or BP velocity. CAFF 9mg was needed to enhance BP velocity and SQ power at the heaviest load (90% 1RM) and cycling peak power output (6.8%-11.7%, P = 0.03-0.05). The CAFF 9mg trial drastically increased the frequency of the adverse side effects (15%-62%).

CONCLUSIONS:

The ergogenic dose of caffeine required to enhance neuromuscular performance during a single all-out contraction depends on the magnitude of load used. A dose of 3 mg · kg(-1) is enough to improve high-velocity muscle actions against low loads, whereas a higher caffeine dose (9 mg · kg(-1)) is necessary against high loads, despite the appearance of adverse side effects.

PMID:
23669879
DOI:
10.1249/MSS.0b013e31829a6672
[Indexed for MEDLINE]

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