The present study investigated the influence of mouth rinsing a carbohydrate solution on self-selected intermittent variable speed running performance. Eleven male soccer players completed a modified version of the Loughborough Intermittent Shuttle Test (LIST) on two occasions separated by 1 week. The modified LIST allowed the self-selection of running speeds during block 6 of the protocol (75-90 min). Players rinsed and expectorated 25 ml of non-caloric placebo (PLA) or 10% maltodextrin solution (CHO) for 10 s, routinely during block 6 of the LIST. Self-selected speeds during the walk and cruise phases of the LIST were similar between trials. Jogging speed was significantly faster during the CHO (11.3 ± 0.7 km·h-1) than during the PLA trial (10.5 ± 1.3 km · h-1) (P=0.010). 15 m sprint speeds were not different between trials (PLA: 2.69 s ± 0.18 s: CHO: 2.65 s ± 0.13 s) (F (2, 10), P = 0.157) but significant benefits were observed for sprint distance covered (P = 0.024). The threshold for the smallest worthwhile change in sprint performance was set at 0.2 s. Inferential statistical analysis showed the chance that CHO mouth rinse was beneficial, negligible or detrimental to repeated sprint performance was 86%, 10% and 4% respectively. In conclusion, mouth rinsing and expectorating a 10% maltodextrin solution was associated with a significant increase in self-selected jogging speed. Repeated 15 m sprint performance was also 86% likely to benefit from routinely mouth rinsing a carbohydrate solution in comparison to a taste matched placebo.
Int J Sport Nutr Exerc Metab