A re-examination of running energetics in average and elite distance runners

We measured the gross rates of oxygen consumption (V˙O2, mlO2·kg-1·km-1) and energy expenditure (E, kcals.kg-1·min-1), and determined the oxygen (O2COT, mlO2·kg-1·km -1) and energetic (ECOT, kcals.kg-1.km-1) costs of transport in Average and Elite runners over a wide range of submaximal speeds. Stride frequency (SF) and length (SL) were measured at each running speed. Ten Average (10 km run time=40-60 min) and 10 Elite (10 km run time<30 min, 10 km run time<31 min at altitude) male runners performed two progressive, submaximal treadmill economy tests on a high-speed force monitoring treadmill. V˙O2 and Ė vs. speed relationships were best described by linear models over the range of speeds achieved by Average subjects. V˙O2 and Ė vs. speed relationships were best described by a curvilinear model over the wider range of speeds achieved by Elite runners (p<.05). O2COT or ECOT was found to decrease from 107-161 meters·min-1 for Average and Elite runners. For Elite runners, a significant increase in ECOT (8.8%) and O2COT (11.3%) was observed from 214 meters·min -1 to 308 meters·min-1 (p<.001). No correlation between changes in SF or SL and changes in COT was observed in Elite subjects from moderate to fast speeds. V˙O2 and E; vs. speed relationships were linear at moderate speeds and curvilinear over wider ranges of submaximal speeds. Measurements of O2COT and ECOT at moderate speeds underestimate the energetic demand of running at speeds approaching elite race pace. The changes in COT observed over moderate to fast running speeds were not explained by changes in SF or SL.