Estimation of maximal oxygen consumption and heart rate recovery using the Tecumseh sub-maximal step test and their relationship to cardiovascular risk factors

BACKGROUND Maximum aerobic capacity (VO2max) is associated with lower cardiovascular and total mortality. Step tests can be used to provide an estimate of (VO2max) in epidemiological or home-based studies. We compared different methods of estimation of VO2max and heart rate recovery and evaluated the relationship of these estimates with cardiovascular risk factors. METHODS Data were analysed from 2286 participants in the Tecumseh Community Health Study (>16y and <70y) who performed a step test. VO2max was estimated from heart rate using three methods and the results compared. The magnitude of heart rate recovery (HRR) and the time constant of recovery based on different time intervals post-exercise were also estimated. RESULTS Estimated VO2max showed good or poor agreement depending on the method used. VO2max correlated inversely with systolic blood pressure (SBP), body mass index (BMI), total cholesterol, blood glucose following a 100g oral load (PLG) and Framingham risk score. In a multivariable model age sex, cigarette smoking, SBP, BMI and PLG were significantly inversely associated with VO2max. Correlations with risk factors were strongest for HRR measured over the first 30s of recovery. Only the time constant calculated from the 3 min post-exercise period correlated significantly with risk factors. CONCLUSIONS The Tecumseh step test can be used to provide estimates of VO2max and heart rate recovery. Estimated VO2max was inversely associated with higher systolic BP, higher BMI and worse glucose tolerance. Measurements of HRR over the first 30s and the time constant calculate from the first 3 min of recovery correlate most closely with risk factors.