RACLET: the Ramp Above Critical Level Endurance Test to evaluate critical velocity in running.

Critical velocity ([Formula: see text]) 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 [Formula: see text] 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,  [Formula: see text], fatigability index τ, and distance reserve above [Formula: see text] [Formula: see text] were determined by adjusting the fatigability model on the measured [Formula: see text]. The RACLET test vs. retest and RACLET test vs. time-trials parameters were compared for reliability and validity testing, respectively. [Formula: see text] differed by -1.9±2.9% between test and retest, and by 5.4±7.1%, between RACLET test and time-trials. Although τ and [Formula: see text] presented important variability (s.d. difference ≈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.