LATE-BREAKING ABSTRACT: Maximum oxygen uptake (maxVO2) during a 6-minute step test (6-MST) in healthy people: Validation of a low cost exercise test

Introduction: Stepping has been one of the first proposed exercise tests but is not been adequately studied regarding cardiopulmonary parameters. Aims and objectives: Measuring cardiopulmonary and metabolic exercise indices in a 6-MST. Methods: Healthy volunteers were included in the study. Exercise protocol imposed ascending and descending a single step 23cm high with a rate of at least 20steps/minute and 3-minute recovery period. Blood pressure, ECG and expired gases were measured. Subjects were considered to have achieved maxVO2 when respiratory quotient (RQ)>1.1 or the 90% of individual9s estimated max heart rate. Results: Twenty two subjects (13 males/9 females) aged 38,64±6,22years old were included in the study. All of them achieved RQ>1.1 but only 7 out of 22 the estimated maxHR>90% (mean value 84,53%±8,54). They ascended and descended 158,27±21,76steps, producing 177,54±31,06Joules/step and a total mechanical work of 27.800±6960Joules with a power of 77,22±19,33Watts. PeakVO2 was measured 1.756,00±414,67mL/min or 21,75±2,97mL/Kg/min equivalent with 6,21±0,85METS. Expired VCO2 at peak exercise was measured 1.846,22 ±443,50mL/min. Anaerobic Threshold (AT) occurred at 57,29%±14,50 of the predicted peakVO2. We found that for every 1mL/min of peakVO2 uptake a mechanical work of 0,06±0,008Joules was produced. PeakVO2 was found to be statistically correlated with measured peakVCO2, AT, estimated maxHR, maxVE, maxVT, VD/VT and total mechanical work (p Conclusions: 6-MST seems to be a reliable submaximal exercise test which could be applied in everyday clinical practice, provided that it needs cheaper equipment compared to conventional exercise tests.