RT Journal Article SR Electronic T1 The effects of creatine supplementation on selected factors of tennis specific training JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP 507 OP 512 DO 10.1136/bjsm.2005.022558 VO 40 IS 6 A1 B M Pluim A1 A Ferrauti A1 F Broekhof A1 M Deutekom A1 A Gotzmann A1 H Kuipers A1 K Weber YR 2006 UL http://bjsm.bmj.com/content/40/6/507.abstract AB Background: Creatine supplementation is popular among tennis players but it is not clear whether it actually enhances tennis performance. Objectives: To examine the effects of creatine supplementation on tennis specific performance indices. Methods: In a randomised, double blind design, 36 competitive male tennis players (24 creatine, mean (SD) age, 22.5 (4.9) years; 12 placebo, 22.8 (4.8) years) were tested at baseline, after six days of creatine loading, and after a maintenance phase of four weeks (14 creatine, 10 placebo). Serving velocity (10 serves), forehand and backhand velocity (three series of 5×8 strokes), arm and leg strength (bench press and leg press), and intermittent running speed (three series of five 20 metre sprints) were measured. Results: Compared with placebo, neither six days nor five weeks of creatine supplementation had a significant effect on serving velocity (creatine: +2 km/h; placebo: +2 km/h, p = 0.90); forehand velocity (creatine: +4 km/h; placebo: +4 km/h, p = 0.80), or backhand velocity (creatine: +3 km/h; placebo: +1 km/h, p = 0.38). There was also no significant effect of creatine supplementation on repetitive sprint power after 5, 10, and 20 metres, (creatine 20 m: −0.03 m/s; placebo 20 m: +0.01 m/s, p = 0.18), or in the strength of the upper and lower extremities. Conclusions: Creatine supplementation is not effective in improving selected factors of tennis specific performance and should not be recommended to tennis players.