Effect of caffeine during repeated explosive vertical jumping

The effect of caffeine on anaerobic power during 60 s of jumping test was studied in six women and seven men. The electromyography activity (EMG) of vastus lateralis muscle was continuously recorded and blood lactate (LA) concentration was measured before the test, immediately after its cessation and 5 min afterwards. The average anaerobic power was significantly increased after caffeine ingestion in comparison with placebo (P<0.004). Caffeine ingestion did not influence EMG of working muscles. It increased significantly blood LA concentration only after 5 min of the recovery period (P<0.02). It can be speculated that caffeine enhances energy production in working muscle. A direct effect of caffeine on the central nervous system, reducing the perception of fatigue, cannot be excluded.