Purpose:
Caffeine has been found to have an ergogenic effect on intermittent-sprinting performance and sport-specific agility (Stuart et al. 2005; Schneiker et al. 2006). However, racquet sports events (tennis, squash and badminton) which demand various repeated short-term high intensity exercise bouts have had little attention in this field. Caffeine can potentially reduce time to exhaustion, enhance concentration and dampen pain perception; all of which have been postulated to improve racquet sport performance (Hornery et al. 2007). The study aimed to investigate the effects of caffeine supplementation on the on-court movements used in racquet sports during a specific agility test.
Methods:
Following institutional ethical approval, eight competitive male racquet sports players were recruited (Age: 21.0 + 1.69, Stature: 1.75 + 0.05-cm, Mass: 72.9 + 7.9-kg). A randomised double-blind experiment was conducted which used two undistinguishable solutions (6-mg.kg-1); caffeine powder (CAF), and placebo (PL). Solutions were administered 60-min prior to testing in a counter-balanced design. Performance was measured by the time to completion (s) on two trials of the ‘four –corner’ agility test (Ooi et al. 2009) separated by a 2-min rest between bouts. Physiological variables measured included heart rate (HR), blood lactate (B.lac) and blood glucose (B.glu) which were recorded immediately at the end of each trial.
Results:
There was a significant difference (P < 0.05) in the time taken to complete the test between CAF (45.63 ± 3.66-s) and PL (47.57 ± 3.67-s) in the first trial (T1). There was also a significant (P < 0.05) increase in B.glu concentrations during T1 for CAF (CAF: 4.37 ± 0.12-mmol.l-1 vs. PL: 3.80 ± 0.33-mmol.l-1). The second trial (T2) showed a significant (P < 0.05) reduction in the time to complete the test with CAF (44.91 ± 4.78-s) compared to PL (46.70 ± 4.64-s). Furthermore, a significantly higher B.glu in the T2 was recorded with CAF (CAF: 4.69 + 0.30-mmol.l-1 vs. PL: 4.00 + 0.25-mmol.l-1). There were no significant differences in HR or B.lac between both the conditions during the two trials.
Conclusions:
A moderate dosage of caffeine, consumed 1-h before two bouts of a specific racquet agility test induced decreased time to completion during each trial compared to a placebo. Practically this could lead to more efficient on-court movements and improved positioning prior to a playing a shot. The increase in blood-bourne glucose levels following caffeine ingestion may have deferred fatigue within the glycolytic energy system allowing for increased performance
