Predictive equations to estimate peak aerobic capacity and peak heart rate in persons with Down syndrome
Estimations based on the available equations for predicting oxygen uptake (VO2) from treadmill speed of locomotion are not appropriate for individuals with Down syndrome (DS). We aimed at developing prediction models for peak absolute oxygen uptake (VO2peak) and peak heart rate (HRpeak) based on retrospective data from a healthy population with and without Down syndrome (DS). A cross-sectional analysis of VO2peak and HRpeak was conducted in 196 and 187 persons with and without DS, respectively, aged from 16-45 years. Non-exercise data alone versus combined with HRpeak were used to develop equations predictive of absolute VO2peak. Prediction equations for HRpeak were also developed. Two additional samples of participants (30 with, 29 without DS) enabled model cross-validation. Relative VO2peak and HRpeak were lowest for persons with DS across all ages (~ 40% and 20 bpm, respectively). For persons with DS, VO2peak predictions provided no differences compared with actual values. Predicted HRpeak was similar to actual values in both groups of participants. Large limits of agreement were obtained for VO2peak (DS: 735, non-DS: 558.2 mL.min-1) and HRpeak (DS: 24.8, non-DS: 16.6 bpm). Persons with DS exhibit low levels of VO2peak and HRpeak in all age groups included in this study. It is possible to estimate absolute VO2peak in persons with DS using non-exercise variables. HRpeak can be accurately estimated in groups of people with and without DS. Yet, because of large limits of agreement, caution is advised if using these equations for individual estimations of VO2peak or HRpeak in either population.