Research into exercise and hydration is not new. Twenty-five years ago, White and Ford1 reported on the voluntary dehydration (hypohydration) during a competitive cycling road race; subjects' mean body mass losses were greater than 3%, and there were low rates of fluid ingestion despite fluid being freely available. It is notable that there was no relationship between fluid intake and finishing position. The BJSM published one of the first consensus statements on fluid replacement2 during and after exercise.

In the October issue of BJSM, Marino and colleagues3 challenge the common belief that (full) fluid replacement is necessary to maintain/improve high-intensity exercise performance in moderate and warm conditions. Their data show neuromuscular adjustments according to hydration status allowing the attainment of similar …