Many team sports such as football, rugby, basketball and hockey are stop–start in nature and consist of prolonged periods of exercise with repeated intermittent high-intensity bursts interspersed with lower intensity exercise. Successful performance in these sports involves fatigue resistance, but also relies on cognitive function for decision-making as well as proper execution of complex skills. This makes assessment of sport performance challenging to study. However, a number of protocols have been developed which have attempted, amongst other things, to investigate the effect hydration status may have on aspects of sports performance. In many of the studies undertaken in this area, the protocol involved allowing dehydration to develop in one trial and preventing it in another by provision of drinks. However, the drink provided has frequently been a specific sports energy drink and thus the influence of carbohydrate or other components in the drink on the outcomes measured cannot always be distinguished from any effects due to prevention of dehydration.
Studies investigating aspects of football performance have reported that fluid replacement with flavoured water, sufficient to limit body mass loss to 1.4%, prevented a reduction in skill performance compared with performance when body mass was reduced by 2.5%, and that body mass reductions of 2.4% and 2.1% resulted in 13% and 15% reductions in test performance in comparison with a trial when drinking resulted in a body mass reduction of only 0.7%.
In a study investigating basketball performance, when body mass losses of up to 4% were created by allowing or withholding drinks during exercise in the heat prior to performing a sequence of basketball drills, it was reported that performance during all timed and shooting drills declined progressively as dehydration increased from 0 to 4% body mass loss and the performance decrement reached statistical significance at 2% body mass loss for combined timed and shooting drills.