The reproducibility of performance in a laboratory test impacts on the statistical
power of that test to detect changes of performance in experiments. The purpose of
this study was to determine the reproducibility of performance of distance runners
completing a 60 min time trial (TT) on a motor-driven treadmill. Eight trained distance
runners (age 27 ± 7 yrs, peak oxygen consumption [VO2peak] 66 ± 5 ml · min-1 · kg-1, mean ± SD) performed the TT on three occasions separated by 7-10 days. Throughout
each TT the runners controlled the speed of the treadmill and could view current speed
and elapsed time, but they did not know the elapsed or final distance. On the basis
of heart-rate, it is estimated that the subjects ran at an average intensity equivalent
to 80 - 83 % of VO2peak. The distance run in 1 h did not vary substantially between trials (16.2 + 1.4
km, 15.9 ± 1.4 km, and 16.1 ± 1.2 km for TTs 1 - 3 respectively, p = 0.5). The coefficient
of variation (CV) for individual runners was 2.7 % (95 % CI = 1.8 - 4.0 %) and the
test-retest reliability expressed as an intraclass correlation coefficient was 0.90
(95 % CI = 0.72 - 0.98). Reproducibility of performance in this test was therefore
acceptable. However, higher reproducibility is required for experimental studies aimed
at detecting the smallest worthwhile changes in performance with realistic sample
sizes.
Key words
Distance running - reliability - tests - time trial - validity
