No ergogenic effect of caffeine in intermittent game sports exercise?

The aim of the study was a detailed analysis of the effects of caffeine consumption during an intermittent tennis test. - Methods: On two experimental days 12 female (age 21.8+/-2.4 years; BMI 21.1+/-1.7 kg/m(2)) and 12 male (age 23.6+/-2.2 years; BMI 22.6+/-1.6 kg/m(2)) tournament tennis players completed the same protocol which consisted of a 60 min singles match (M) followed by a 30 min standardized match simulation (MS) by the use of a ball-machine and a 30 min intermittent exercise drill (ID). One hour pre-exercise we administered double blind and randomized either 5 mg/kg caffeine (C) or an identically flavoured placebo (P). Results: Blood lactate concentration in M (C: 2.45+/-0.86 vs. P: 1.65+/-0.57 mmol/l), MS (C: 3.82+/-1.29 vs. P: 2.60+/-0.95 mmol/l) and ID (C: 6.51+/-2.10 vs. P: 5.00+/-2.41 mmol/l) was significantly increased after caffeine consumption. Percentage of points won in M (C: 48.9+/-9.9 vs. P: 51.1+/-9.9 No), percentage of errors in MS (C: 33.4+/-7.6 vs. P: 33.7+/-9.4 %) as well as the stroke velocity in ID (C: 101.8+/-9.7 vs. P: 100.0+/-8.1 km/h) were not affected by caffeine. Perceived exertion (RPE-scale) and motivation (10 point scale) did not show a main effect between C and P. No gender-specific differences were found. Conclusions: Administration of a low caffeine dosage during an intermittent tennis test increases the glycolytic activity, pointing to a higher utilization of carbohydrates. Tennis-specific performance does not seem to be increased by caffeine in men and women.