Reliability and variability of running economy in elite distance runners

PURPOSE: To establish the typical error (TE) associated with equipment, testing, and biological variation of a running economy (RE) test in 11 elite male distance runners ([latin capital V with dot above]O2max 70.3 +/- 7.3 mL[middle dot]min-1[middle dot]kg-1), and measure the between-athlete variation of 70 highly trained runners ([latin capital V with dot above]O2max 69.7 +/- 6.0 mL[middle dot]min-1[middle dot]kg-1) to determine the magnitude of the smallest worthwhile change (SWC) required for RE. CONCLUSIONS: The results demonstrate that although the magnitude of the TE for a submaximal treadmill running protocol of three 4-min work efforts is small (2.4-7.3%) for measures associated with cardiorespiratory parameters, it is three- to fourfold higher for Lac. Given the small TE associated with RE, and a SWC of similar magnitude for this cohort of distance runners, the RE test is useful in detecting changes attributable to training interventions. Changes in RE greater than ~2.4% in this cohort of elite distance runners are likely to be "real" and "worthwhile," and not simply related to testing error and typical variation.