How Accurate Is the Prediction of Maximal Oxygen Uptake with Treadmill Testing?

<div><p>Background</p><p>Cardiorespiratory fitness measured by treadmill testing has prognostic significance in determining mortality with cardiovascular and other chronic disease states. The accuracy of a recently developed method for estimating maximal oxygen uptake (VO_2peak), the heart rate index (HRI), is dependent only on heart rate (HR) and was tested against oxygen uptake (VO₂), either measured or predicted from conventional treadmill parameters (speed, incline, protocol time).</p><p>Methods</p><p>The HRI equation, METs = 6 x HRI– 5, where HRI = maximal HR/resting HR, provides a surrogate measure of VO_2peak. Forty large scale treadmill studies were identified through a systematic search using MEDLINE, Google Scholar and Web of Science in which VO_2peak was either measured (TM-VO_2meas; n = 20) or predicted (TM-VO_2pred; n = 20) based on treadmill parameters. All studies were required to have reported group mean data of both resting and maximal HRs for determination of HR index-derived oxygen uptake (HRI-VO₂).</p><p>Results</p><p>The 20 studies with measured VO₂ (TM-VO_2meas), involved 11,477 participants (median 337) with a total of 105,044 participants (median 3,736) in the 20 studies with predicted VO₂ (TM-VO_2pred). A difference of only 0.4% was seen between mean (±SD) VO_2peak for TM- VO_2meas and HRI-VO₂ (6.51±2.25 METs and 6.54±2.28, respectively; p = 0.84). In contrast, there was a highly significant 21.1% difference between mean (±SD) TM-VO_2pred and HRI-VO₂ (8.12±1.85 METs and 6.71±1.92, respectively; p<0.001).</p><p>Conclusion</p><p>Although mean TM-VO_2meas and HRI-VO₂ were almost identical, mean TM-VO_2pred was more than 20% greater than mean HRI-VO₂.</p></div

Heart rate and oxygen consumption data for TM-VO_2meas and TM-VO_2pred.

<p>Group mean (± 1SD) heart rate (HR) and oxygen consumption (VO₂) data. HR_rest, HR_peak, HRI-VO₂ and VO_2peak for TM-VO_2meas and TM-VO_2pred.</p

Comparison of pooled data from 20 studies for TM-VO_2meas and TM-VO_2pred against HRI-VO₂.

<p>A. Comparison of group mean data for 20 TM-VO_2meas and TM-VO_2pred studies against HRI-VO2 (mean ± SE), B. Comparison of cardiorespiratory fitness tertiles from 20 studies for TM-VO_2meas against HRI-VO₂ (mean ±SE). Percentage difference between TM-VO_2meas and HRI-VO₂ shown within figure and C. Comparison of cardiorespiratory fitness tertiles from 20 studies for TM-VO_2pred against HRI-VO₂ (mean ±SE). Percentage difference between TM-VO_2pred and HRI-VO₂ shown within figure.</p

Line of identity and Bland Altman plot for TM-VO_2meas.

<p>A. Line of identity for TM-VO_2meas and B. against Bland Altman plot for TM-VO_2meas against HRI-VO₂.</p

Line of identity and Bland Altman plot for TM-VO_2pred.

<p><b>A.</b> Line of identity for TM-VO_2pred and B. against Bland Altman plot for TM-VO_2pred against HRI-VO₂.</p