Introduction Step climbing is a potentially useful modality for testing exercise capacity. However, there are significant variations between test protocols and lack of consistent validation against gold standard cycle ergometry cardiopulmonary exercise testing (CPET). The purpose of the study was to validate a novel technique of exercise testing using a dedicated device.
Methods We built a step oximetry device from an adapted aerobics step and pulse oximeter connected to a computer. Subjects performed lung function tests, a standard incremental cycle CPET and also a CPET while stepping on and off the step oximetry device to maximal exertion. Data from the step oximetry device were processed and correlated with standard measurements of pulmonary function and cycle CPET.
Results We recruited 89 subjects (57 years, 50 men). Oxygen uptake (VO2) was 0.9 mL/kg/min (95% CI −3.6 to 5.4) higher in the step test compared with the gold standard cycle CPET, p<0.001. VO2 in the two techniques was highly correlated (R=0.87, p<0.001). Work rate during stair climbing showed the best correlation with VO2 (R=0.69, p<0.0001). Desaturation during step climbing correlated negatively with diffusion capacity for carbon monoxide (r=−0.43, p<0.005). No adverse events occurred.
Conclusions The step oximetry test was a maximal test of exertion in the subjects studied, achieving slightly higher VO2 than during the standard test. The test was safe to perform and well tolerated by the patients. Parameters derived from the step oximetry device correlated well with gold standard measurements. The step oximetry test could become a useful and standardisable exercise test for clinical settings where advanced testing is not available or appropriate.
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Contributors BDF conceived the study, built the device, analysed the data and drafted the manuscript. NS collected the data, analysed the data and drafted the manuscript. BV and LF collected the data and revised the manuscript. MRK conceived the study, built the device, analysed the data and revised the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Not required.
Ethics approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data sharing is possible. Please contact the corresponding author.
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