@article {Goulet679, author = {Eric D B Goulet}, title = {Effect of exercise-induced dehydration on endurance performance: evaluating the impact of exercise protocols on outcomes using a meta-analytic procedure}, volume = {47}, number = {11}, pages = {679--686}, year = {2013}, doi = {10.1136/bjsports-2012-090958}, publisher = {British Association of Sport and Excercise Medicine}, abstract = {Objective It is purported that exercise-induced dehydration (EID), especially if >= 2\% bodyweight, impairs endurance performance (EP). Field research shows that athletes can achieve outstanding EP while dehydrated \> 2\% bodyweight. Using the meta-analytic procedure, this study compared the findings of laboratory-based studies that examined the impact of EID upon EP using either ecologically valid (EV) (time-trial exercise) or non-ecologically valid (NEV) (clamped-intensity exercise) exercise protocols. Methods EP outcomes were put on the same scale and represent \% changes in power output between euhydrated and dehydrated exercise tests. Random-effects model meta-regressions and weighted mean effect summaries, mixed-effects model analogue to the ANOVAs and magnitude-based effect statistics were used to delineate treatment effects. Main results Fifteen research articles were included, producing 28 effect estimates, representing 122 subjects. Compared with euhydration, EID increased (0.09{\textpm}2.60\%, (p=0.9)) EP under time-trial exercise conditions, whereas it reduced it (1.91{\textpm}1.53\%, (p\<0.05)) with NEV exercise protocols. Only with NEV exercise protocols did EID >= 2\% body weight impair EP (p=0.03). Conclusions Evidence indicates that (1) EID <= 4\% bodyweight is very unlikely to impair EP under real-world exercise conditions (time-trial type exercise) and; (2) under situations of fixed-exercise intensity, which may have some relevance for military and occupational settings, EID >= 2\% bodyweight is associated with a reduction in endurance capacity. The 2\% bodyweight loss rule has been established from findings of studies using NEV exercise protocols and does not apply to out-of-doors exercise conditions. Athletes are therefore encouraged to drink according to thirst during exercise.}, issn = {0306-3674}, URL = {https://bjsm.bmj.com/content/47/11/679}, eprint = {https://bjsm.bmj.com/content/47/11/679.full.pdf}, journal = {British Journal of Sports Medicine} }