Carbohydrate-electrolyte drink ingestion and skill performance in tennis

Abstract

ABSTRACT

Aim: To examine the effect of ingesting a carbohydrate-electrolyte drink (CHO-E) compared to a flavoured matched placebo electrolyte drink (PL) on maintenance of skill and performance over 2 hours of indoor tennis match play.

Method: Twenty-two nationally ranked tennis players (15 male, 7 female; mean (SD) height 177 (8) cm, weight 69.2 (9.5) kg) reported to the test centre on four separate occasions, with the first two visits for screening and familiarisation. The final two visits were main trials and participants attended the lab 3 hours post-prandial for baseline nude body mass and blood sample collection. They then performed a standardised warm-up and pre-match skill test, a 2 hour tennis match with ingestion of either CHO-E (Lucozade Sport, GlaxoSmithKline Nutritional Healthcare) or PL beverage administered as a bolus volume (5ml/kg) prior to warm-up, and subsequent volumes (3 ml/kg) every 20 minutes. A final post-match skill test was performed and nude body mass recorded. During the trials, participant’s heart rate and movement intensity were monitored, and the match was recorded using a video camera for later match analysis.

Results: There was no difference in environmental conditions or hydration status measures between trials and no difference in skill test scores pre and post-match or between trials at each of these times. Participants on the CHO-E trial had elevated blood glucose concentration throughout the match and also reported feeling more energetic (general activation) and more tense (high activation) one hour into the match compared to baseline, which was not observed in the placebo trial (time x trial interaction p<0.05). In addition, accelerometer data showed participants on the CHO-E trial spent more time in moderate intensity activity and less time in low intensity activity than on PL. Match analysis data revealed that ingestion of the CHO-E beverage significantly increased overall percentage of successful serves (mean ± SD = 68 ± 7% for CHO-E compared to 66 ± 7% for PL; p<0.05), in particular first serves (65 ± 9% for CHO-E, 61 ± 7% for PL; p<0.01) and serves to the advantage side (70 ± 9% for CHO-E, 66 ± 7% for PL; p<0.05) over the duration of the whole match. Furthermore, a significant increase in return success rates was observed during the second set of the match (p<0.05) on the CHO-E trial. However, performance improvements on the serve and return were found not to be associated with the increase in blood glucose nor player ability.

Conclusions: CHO-E drink ingestion during a tennis match can contribute towards maintaining performance by increasing overall percentage of successful serves and increasing return success rates. These changes may be linked to increased perceived activation, and increased intensity of movement sustained on court. However, the improvements in serve and return success rates are not associated with player ability or glucose elevation, but may reflect a more generic central brain mediated effect of carbohydrate ingestion on skill.

This work was supported by GlaxoSmithKline Nutritional Healthcare.