Efficacy of estimating VO₂max with the Heart Rate Ratio Method in middle-aged and older adults

Purpose: Investigate difference, agreement, and bias between maximal oxygen consumption (VO₂max) measured by indirect calorimetry and the Heart Rate Ratio Method (HRRM) for estimating VO₂max using measured and age-predicted maximum heart rate (HRmax) in a sample of middle-aged and older adults.

Methods: Eleven men and nine women (age: 61.8 ± 8.5 years, VO₂max: 36.6 ± 9.5 mL/kg/min, N = 20) had their VO₂max measured via a maximal graded exercise test and confirmed using a verification bout on a treadmill ergometer. Participants' VO₂max was estimated via the HRRM using measured and age-predicted HRmax. Difference, agreement, and bias between methods were assessed using a one-way repeated measures Analysis of Variance (ANOVA), Lin's concordance correlation coefficient, and Bland-Altman plots, respectively.

Results: There were no statistical differences between methods of assessing VO₂max, F(1.13, 21.47) = 0.583, p = 0.473, generalized eta-squared = 0.012. The standard error of the estimate (SEE) for the HRRM using measured or predicted HRmax was 5.2% and 5.6% of the mean VO₂max, respectively. Both HRRM predictions had poor agreement with VO₂max (r_c ≤ 0.40). There was a systematic bias to underestimate as VO₂max increased for HRRM using measured HRmax, F(1, 18) = 17.40, p < 0.001, and when using an age-predicted HRmax, F(1, 18) = 13.39, p = 0.002.

Conclusion: Both versions of the HRRM have poor agreement, relatively large SEEs, and a bias to misrepresent VO₂max. When possible, VO₂max should be measured via a maximal graded exercise test with indirect calorimetry for middle-aged and older adults.