ObjectiveThe main aim of this study was to examine the association between the Maximal Aerobic Speed (MAS) measured by the Université de Montréal Track Test (UM-TT) and on a running treadmill test in young elite soccer players.Equipment and methodsFourteen U-16 male soccer players (mean ± SD: age = 15.5 ± 0.7 years; height = 1.76 ± 0.5 m; weight = 67.7 ± 4.5 kg) from a Spanish First Division club academy participated in the study. The participants were submitted to the Université de Montréal Track Test (UM-TT) and an intermittent treadmill test with a one-week interval.ResultsThe MASs, the speed at the last completed stage (16.6 ± 0.8 km h−1) and calculated using the formula of Kuipers et al. (17.2 ± 0.7 km h−1), were substantially higher (Effect size > 0.8) than that measured on the treadmill (15.9 ± 0.9 km h−1). The MAS measured by the UM-TT correlated highly (r > 0.6) with the MAS measured on the treadmill.ConclusionDespite the large association between both values, the MAS measured by the UM-TT differs considerably from the MAS measured on a running treadmill in young elite soccer players. It suggests that, in soccer training, caution should be applied when using the velocity of the MAS measured on the UM-TT or in a laboratory interchangeably.