A new energetics model for the assessment of the power-duration relationship during over-ground running.

We evaluated the reliability of an over-ground running three-minute all-out test (3MT) and compared this to traditional multiple-visit testing to determine the critical speed (CS) and distance > CS (´). Using a novel energetics model during the 3MT, critical power (CP) and work > CP () were also evaluated for reliability and compared to the multiple-visit tests. Over-ground running speed was measured using Global Positioning Systems during fixed-speed trials on a 400 m track to exhaustion, at four intensities corresponding to: (i) maximal oxygen uptake (V), (ii) 110% , (iii) Δ70% (i.e. 70% of the difference between gas exchange threshold and V) and (iv) Δ85%. The participants subsequently performed the 3MT across two days to determine its reliability. There were no differences between the multiple-visit testing and the 3MT for CS ( = 0.328) and ´ ( = 0.919); however, CP ( = 0.02) and ( < 0.001) were higher in the 3MT. The reliability of the 3MT was stable ( > 0.05) between trials for all variables, with coefficient of variation ranging from 2.0-8.1%. The current over-ground energetics model can reliably estimate CP and based on GPS speed data during the 3MT, which supports its use for most athletic training and monitoring purposes. The reliability of the over-ground running 3MT for power- and speed-related indices was sufficient to detect typical training adaptations; however, it may overestimate CP (∼ 25 W) and (∼ 7 kJ) compared to multiple-visit tests.