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Resting Heart Rate Is a Biomarker of Cardiorespiratory Fitness: The Fenland Study
33 Pages Posted: 3 May 2022
More...Abstract
Background: Few large studies have evaluated the relationship between resting heart rate (RHR) and cardiorespiratory fitness. Here we examine cross-sectional and longitudinal relationships between RHR and fitness, explore factors that influence these relationships, and demonstrate the utility of RHR for remote population monitoring.
Methods: In cross-sectional analyses (The UK Fenland Study: 5,722 women, 5,143 men, aged 29-65y), we measured RHR (beats per min, bpm) while seated, supine, and during sleep. Fitness was estimated as maximal oxygen consumption (ml⋅min-1 ⋅kg-1) from an exercise test. Associations between RHR and fitness were evaluated while adjusting for age, sex, obesity, and physically activity. In longitudinal analyses (6,589 participants), we reassessed RHR and fitness after a median of 6 years and evaluated the association between within-person change in RHR and fitness. During the coronavirus disease-2019 pandemic, we used a smartphone application to remotely and serially measure RHR (1,914 participants, August 2020 to April 2021) and examined differences in RHR dynamics by pre-pandemic fitness.
Findings: Mean RHR while seated, supine, and during sleep was 67, 64, and 57 bpm. Age- and sex-adjusted associations (beta coefficients) between RHR and fitness were -0.26, -0.31, and -0.31 ml⋅kg-1 ⋅beat-1. Adjustment for obesity and physical activity attenuated the RHR-to-fitness relationship by 10% and 50%, respectively. A 1-bpm increase in supine RHR was associated with a 0.23 ml⋅min-1⋅kg-1 decrease in fitness. During the pandemic, RHR increased in those with low fitness but was stable in others.
Interpretation: RHR is a valid biomarker of cardiorespiratory fitness.
Funding Information: The authors were supported by the UK Medical Research Council (MC_UU_12015/1, MC_UU_12015/3, MC_UU_12015/4, MC_UU_12015/5) and the NIHR Cambridge Biomedical Research Centre (IS-BRC-1215-20014).
Declaration of Interests: No author declares any competing interest, no support from any additional organizations for the submitted work, no financial relationships with any organizations that might have an interest in the submitted work in the previous three years, and no other relationships or activities that could appear to have influenced the submitted work.
Ethics Approval Statement: The study complies with the Declaration of Helsinki and was approved by the Health Research Authority NRES Committee East of England-Cambridge Central. All participants gave written informed consent. The Fenland Study has a dedicated Patient and Public Involvement panel, who provided input on the acceptability of the study protocols and how participant data confidentiality was ensured.
Keywords: Resting Heart Rate, Heart Rate, Cardiorespiratory Fitness, Physical Activity, VO2max, COVID-19
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