Critical velocity ( \(V_c\) ) is an important fatigability threshold in running, but only strenuous methods exist to assess it (e.g. time-trials). Based on a novel mathematical model of fatigability, the Ramp Above Critical Level Endurance Test (RACLET), a simple 5-min test to evaluate \(V_c\) was developed. This study aimed to test the measurement properties of this novel non-exhaustive test. Thirty-eight participants performed two RACLET (session 1) and three time-trials (sessions 2–4). For the RACLET, velocity target tracking was guaranteed by either a pacing bike or cones and whistle signals. Using GPS to measure participants’ running velocities, \(V_c\) , fatigability index \(\tau\) , and distance reserve above \(V_c\) \(D_{AC_{\max }}\) were determined by adjusting the fatigability model on the measured \(V_{\max }\) . The RACLET test vs. retest and RACLET test vs. time-trials parameters were compared for reliability and validity testing, respectively. \(V_c\) differed by −1.9±2.9% between test and retest, and by 5.4±7.1%, between RACLET test and time-trials. Although \(\tau\) and \(D_{AC_{\max }}\) presented important variability (s.d. difference \(\approx\) 30%), the combination of the RACLET parameters enabled a good prediction of time-trials performance (mean error=8.5±5.0%, 0.1±7.6%, −2.0±5.5% for 400, 1500, and 3000 m, respectively). RACLET is a promising non-exhausting test to assess the velocity–time relationship parameters.
