Background and Objectives: The maximum aerobic poweris an important predictor of endurance performance and is closely associated with an individual's Cardiorespiratory Fitness (CRF). Being able to screen for changes in CRF cost effectively as well as identifying variables to provide accurate values for aerobic fitness has been identified by numerous studies. The purpose of the present study was to investigate whether published models were valid predictors of CRF in young adults using previously unpublished 20 m SRT (shuttle run test) data. Methods: Estimated max VO values from 20m SRT performance were compared across three published models using an independent data set of 178 participants (89 men; age 22.8 ± 4.2 years, height 1.80 ± 0.07 m, body mass 79.8 ± 12.4 kg and 89 women; age 21.3 ± 2.4 years, height 1.67 ± 0.06 m, body mass 62.6 ± 9.3 kg). Closeness-of-fit was assessed using means and standard deviation and bias.Results: An allometric model provided a superior fit, with less bias, compared with two published linear regression equations. Directly measured 2 max VO  values were 51.2 ± 8.6 ml kg -1 min -1 compared with 49.8 ± 9.3 (allometric model) versus 46.8 ± 7.9 and 44.4 ± 9.1 ml kg -1 min -1 for the two linear models respectively. Conclusion:An allometric model provided more accurate predictions of CRF (ml kg -1 min -1 ) in young adults compared with two published linear models.