Purpose: The aim of this study was to evaluate the predictive ability of the sprint power reserve model in the extreme and severe intensity domains by comparing predictions from laboratory and field conditions with field-recorded mean maximum power outputs (MMPs). Methods: Ten male U23 (under 23 y of age) cyclists participated in this study (height 182.9 [4.7] cm; body mass 71.4 [6.5] kg; VO2max 74.2 [3.1] mL·kg-1·min-1). Participants completed an incremental graded exercise test and a 10-second sprint test in the laboratory, as well as a 3-minute field test and a 10-second sprint test in the field (PmaxFIELD). Predictions from laboratory (PREDLAB) and field (PREDFIELD) were compared via Bland-Altman plots with MMP over 15-, 30-, 60-, 90-, 120-, and 150-second durations. Results: No significant differences were found between the lab and field 10-second sprint tests, nor between the 3-minute field test and the peak power achieved in the incremental laboratory test (PGXT, P > .05). The sprint-power-reserve time constant k = 0.027 revealed the best fit to MMP (R2 = .98; P <= .001). Apart from a difference between MMP and PREDLAB for 90-second power output (difference = 68 W, P = .04), no further differences were found (P > .05). All predictions of PREDLAB and PREDFIELD of MMP were within 95% limits of agreement, except the 150-second duration for PREDFIELD. Discussion: High-intensity-power-output predictions of the sprint power reserve model derived from laboratory and field conditions present similar levels of reliability, and both can be used by practitioners with confidence.
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