Supplementary data for study: A reappraisal of ventilatory thresholds in wheelchair athletes - do they really exist?

The ventilatory threshold (VT) separates low- from moderate-intensity exercise, the respiratory compensation threshold (RCT) moderate- from high-intensity exercise. Both concepts assume breakpoints in respiratory data. However, the objective determination of VT and the RCT using breakpoint models during upper-body modality exercise in wheelchair athletes has received little attention. Therefore, the aim of this study was to compare the fit of breakpoint models (i.e. two linear regression lines) with continuous no-breakpoint models (i.e. exponential curve/ 2nd order polynomial) to respiratory data obtained during a graded exercise test to exhaustion. These fits were compared employing adjusted R2 and blocked bootstrapping was used to derive estimates of a median and 95% confidence intervals (CI). V̇O2-V̇CO2 and V̇E/V̇O2-time data were assessed for the determination of the VT, and V̇CO2-V̇E and V̇E/ V̇CO2-time data for the determination of the RCT. Data of 9 wheelchair athletes with tetraplegia, 8 with paraplegia and 7 with impairments other than a spinal cord injury were evaluated. In this data repository, in the text file we provide the median adjusted R2 for each individual participant (Supplementary data). Further, we provide a figure that explains how notched boxplots can be interpreted (Fig. S1).