Validation of Maximal, Submaximal, and Nonexercise Indirect Omax Estimations at 2600 m Altitude

To study the criterion validity of three indirect maximal oxygen uptake (Omax) assessment equations at altitude. We studied 64 young adults (53% men) at Bogota, Colombia (2600 m altitude). Direct Omax was measured by indirect calorimetry using a maximal incremental treadmill protocol. Indirect Omax was estimated by two exercise field tests (the 20-m shuttle-run test [20-MST] and the 2-km walking test (UKK)) and one nonexercise method (the perceived functional ability-physical activity rating questionnaire [PFA-PAR]). Altitude-adjusted PFA-PAR was estimated as a 13% linear reduction in PFA-PAR. We calculated Lin concordance coefficients (LCC) and standard error of the estimates (SEEs), and we performed Bland-Altman analyses for each indirect method. Mean Omax was 41.2 ± 5.8 mL/kg/min in men and 32.2 ± 3.6 mL/kg/min in women. We found the highest agreement with direct Omax for the 20-MST (LCC = 0.79, SEE = 3.91 mL/kg/min), followed in order by the altitude-adjusted PFA-PAR (LCC = 0.71, SEE = 4.12 mL/kg/min), the UKK (LCC = 0.67, SEE = 5.48 mL/kg/min), and the unadjusted PFA-PAR (LCC = 0.57, SEE = 4.75 mL/kg/min). The unadjusted PFA-PAR tended to overestimate Omax, but Bland-Altman analysis showed that this bias disappeared after altitude adjustment. Several maximal, submaximal, and nonexercise methods provide estimates of Omax with acceptable validity for use in epidemiological studies of populations living at moderate altitude.