Reliability of power in physical performance tests

The reliability of power in tests of physical performance affects the preci sion of assessment of athletes, patients, clients and study participants. I n this meta-analytic review we identify the most reliable measures of power and the factors affecting reliability. Our measures of reliability were th e typical (standard) error of measurement expressed as a coefficient of var iation (CV) and the percent change in the mean between trials. We meta-anal ysed these measures for power or work from 101 studies of healthy adults. M easures and tests with the smallest CV in exercise of a given duration incl ude field tests of sprint running (similar to0.9%), peak power in an increm ental test on a treadmill or cycle ergometer (similar to0.9%), equivalent m ean power in a constant-power lest lasting 1 minute to 3 hours on a treadmi ll or cycle ergometer (0.9 to 2.0%), lactate-threshold power (similar to1.5 %), and jump height or distance (similar to2.0%). The CV for mean power on isokinetic ergometers was relatively large (>4%). CV were larger for nonath letes versus athletes (1.3 x), female versus male nonathletes(1.4 x), short er(similar to l-second) and longer(similar to l-hour) versus 1-minute tests (less than or equal to1.6 x), and respiratory- versus ergometer-based meas ures of power (1.4 to 1.6 x). There was no clear-cut effect of time between trials. The importance of a practice trial was evident in studies with >2 trials. the CV between the first 2 trials was 1.3 times the CV between subs equent trials; performance also improved by 1.2% between the first 2 trials but by only 0.2% between subsequent trials. These findings should help exe rcise practitioners and researchers select or design good measures and prot ocols for tests of physical performance.