The reliability of running economy among trained distance runners and field-based players

Abstract

Whilst the reliability of running economy (RE) has been widely established, there is limited investigation of the reliability of various performance variables during a RE test. Subsequently, the purpose of the current study was to examine the reliability of time-to-exhaustion (TTE) and rating of perceived exertion (RPE) during a RE test amongst trained runners (TR) and moderately endurance trained men (METM). Absolute O2 (ml.min-1), O2 relative to body mass (ml.kg-1.min-1), oxygen cost of running (CR) defined as O2 relative to body mass raised to the power of 0.75 and metre (ml.kg-0.75.m-1), heart rate (HR), ventilation ( E), carbon dioxide production ( CO2), respiratory exchange ratio (RER) and RPE were measured whilst treadmill running on two occasions at three discontinuous incremental speeds corresponding to 70-, 90- and 110% of the second ventilatory threshold (VT2). The duration of the last increment was measured as TTE. The reliability was determined using intra-class correlation coefficient (ICC) and 95% ratio limits of agreement. The intra-individual variability was examined using coefficient of variation (CV). There were no significant differences between the two RE trials for absolute O2, relative O2, CR, E, CO2, RER and RPE (P ≥ 0.05) except for differences in RPE during the first increment and TTE (P < 0.05). The reliability was high for absolute O2, relative O2, CR, HR and TTE and moderate for E and RPE. Small intra-individual variability was found for absolute O2, relative O2, CR, HR and RPE. The findings will enable sport scientists to incorporate a variety of performance variables when examining RE.