Caffeine Ingestion and Skill Performance during Simulated Soccer Activity

Abstract

There is evidence that caffeine ingestion can enhance endurance performance and also cognitive function although the effects on power output appear equivocal. There is little evidence however on the benefits of caffeine ingestion on performance during sports that are multifaceted in their physiological and cognitive demands, such as soccer. PURPOSE: To examine the influence of caffeine on physiological and performance parameters during simulated soccer activity. METHODS: Ten male competitive soccer players performed two 90-min soccerspecific intermittent running (LIST) trials, separated by 7 days, in a randomised crossover design. On each occasion, subjects ingested a gelatinous capsule containing 6 mg·kg-1 body mass (BM) of either anhydrous caffeine powder (CAF) or a placebo (PLA) in a double-blind fashion along with 500 ml of water 60 min prior to exercise. Heart rate (HR), 15-m sprint performance, counter-movement jump height (CMJ) and ratings of perceived exertion (RPE) were measured during exercise. Movement Time, Penalty Time accrued and Total Time were recorded for the soccer passing test (LSPT); performed prior to and every 15 min during the LIST. Water (3 ml·kg-1 BM) was ingested every 15 min of the LIST in both trials. RESULTS: Penalty Time was significantly lower in the CAF trial (CAF: 8.9 ± 6.8 s vs. PLA: 11.1 ± 7.6 s; P=0.01) leading to a significantly lower Total Time in this trial (CAF: 51.0 ± 8.0 s vs. PLA: 53.8 ± 9.1 s; P=0.02). There were no differences between trials in Movement Time. Similarly, caffeine had no effect on sprint performance, HR or RPE although there was a trend for CMJ performance to be higher in the CAF trial (CAF: 0.57 ± 0.05 m vs. PLA 0.54 ± 0.05 m; P=0.07). There was no evidence that caffeine enhanced diuresis, with similar body mass losses (CAF: 1.0 ± 0.5 kg vs. PLA: 0.9 ± 0.5 kg) and post exercise urine specific gravity values (CAF: 1.021 ± 0.007 vs. PLA: 1.020 ± 0.007) between trials. CONCLUSIONS: Caffeine ingestion prior to soccer match play appears to improve the passing accuracy and ball control of players without any detrimental effects to other physiological or performance parameters. Furthermore, there is some evidence that caffeine may attenuate the decline in leg power that accompanies the fatigue of prolonged intermittent shuttle running.