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Agreement and relationship between measures of absolute and relative intensity during walking: A systematic review with meta-regression

Warner, Ashley; Vanicek, Natalie; Benson, Amanda; Myers, Tony; Abt, Grant


Ashley Warner

Amanda Benson

Tony Myers


Introduction A metabolic equivalent (MET) is one of the most common methods used to objectively quantify physical activity intensity. Although the MET provides an 'objective' measure, it does not account for inter-individual differences in cardiorespiratory fitness. In contrast, 'relative' measures of physical activity intensity, such as heart rate reserve (HRR), do account for cardiorespiratory fitness. The purpose of this systematic review with meta-regression was to compare measures of absolute and relative physical activity intensity collected during walking. Methods A systematic search of four databases (SPORTDiscus, Medline, Academic Search Premier and CINAHL) was completed. Keyword searches were: (i) step*OR walk*OR strid*OR "physical activity"; (ii) absolute OR "absolute intensity"OR mets OR metabolic equivalent OR actigraph*OR acceleromet*; (iii) relative OR "relative intensity"OR "heart rate"OR "heart rate reserve"OR "VO2 reserve"OR VO2*OR "VO2 uptake"OR HRmax*OR metmax. Categories (i) to (iii) were combined using 'AND;' with studies related to running excluded. A Bayesian regression was conducted to quantify the relationship between METs and %HRR, with Bayesian logistic regression conducted to examine the classification agreement between methods. A modified Downs and Black scale incorporating 13 questions relative to cross-sectional study design was used to assess quality and risk of bias in all included studies. Results A total of 15 papers were included in the systematic review. A comparison of means between absolute (METs) and relative (%HRR, %HRmax, %VO2R, %VO2max, HRindex) values in 8 studies identified agreement in how intensity was classified (light, moderate or vigorous) in 60% of the trials. We received raw data from three authors, incorporating 3 studies and 290 participants. A Bayesian random intercept logistic regression was conducted to examine the agreement between relative and absolute intensity, showing agreement in 43% of all trials. Two studies had identical relative variables (%HRR) totalling 240 participants included in the Bayesian random intercept regression. The best performing model was a log-log regression, which showed that for every 1% increase in METs, %HRR increased by 1.12% (95% CI: 1.10-1.14). Specifically, the model predicts at the lower bound of absolute moderate intensity (3 METs), %HRR was estimated to be 33% (95%CI: 18-57) and at vigorous intensity (6 METs) %HRR was estimated to be 71% (38-100). Conclusion This study highlights the discrepancies between absolute and relative measures of physical activity intensity during walking with large disagreement observed between methods and large variation in %HRR at a given MET. Consequently, health professionals should be aware of this lack of agreement between absolute and relative measures. Moreover, if we are to move towards a more individualised approach to exercise prescription and monitoring as advocated, relative intensity could be more highly prioritised.


Warner, A., Vanicek, N., Benson, A., Myers, T., & Abt, G. (2022). Agreement and relationship between measures of absolute and relative intensity during walking: A systematic review with meta-regression. PLoS ONE, 17(11), Article e0277031.

Journal Article Type Review
Acceptance Date Oct 18, 2022
Online Publication Date Nov 3, 2022
Publication Date Nov 1, 2022
Deposit Date Oct 27, 2022
Publicly Available Date Nov 4, 2022
Journal PLoS ONE
Print ISSN 1932-6203
Electronic ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 17
Issue 11
Article Number e0277031
Public URL


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Copyright Statement
Copyright: © 2022 Warner et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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