Heart rate (HR) is important because a high rate can reduce heart rate variability (HRV), the changes in the time intervals between consecutive heartbeats, which are called interbeat intervals (IBIs; Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, 1996). Graphic © arka38/Shutterstock.com.
Faster HRs reduce the time between successive beats and the opportunity for IBIs to vary. Faster HRs lower HRV. Resting HRs that exceed 90 bpm are associated with an elevated risk of mortality (Zhang, Shen, & Qi, 2016) and cognitive decline and dementia (Imahori et al., 2021).
Conversely, the slower HRs seen in endurance sports like trail running increase the time between adjacent heartbeats and the chance for IBIs to vary. This raises HRV. This phenomenon is called cycle length dependence (McCraty & Shaffer, 2015). Graphic © Maridav/Shutterstock.com.
Typical non-athlete HRs are 60-80 bpm. Athletes may have HRs between 40-60 bpm (Khazan, 2019).
Summary
Faster HRs lower HRV, and resting values over 90 bpm increase the risk of cognitive decline and dementia.
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References Imahori, Y., Vetrano, D. L., Xia, X., Grande, G., Ljungman, P., Fratiglioni, L., & Qui, C. (2021). Association of resting heart rate with cognitive decline and dementia in older adults: A population-based cohort study. Alzheimer's & Dementia. https://doi.org/10.1002/alz.12495 Khazan, I. (2019). A guide to normal values for biofeedback. In D. Moss & F. Shaffer (Eds.). Physiological recording technology and applications in biofeedback and neurofeedback (pp. 2-6). Association for Applied Psychophysiology and Biofeedback. McCraty, R. & Shaffer, F. (2015). Heart rate variability: New perspectives on physiological mechanisms, assessment of self-regulatory capacity, and health risk. Glob Adv Health Med, 4(1). 46-61. https://doi.org/10.7453/gahmj.2014.073 Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996). Heart rate variability: Standards of measurement, physiological interpretation, and clinical use. Circulation, 93, 1043-1065. PMID: 8598068 Zhang, D., Shen, X., & Qi, X. (2016). Resting heart rate and all-cause and cardiovascular mortality in the general population: A meta-analysis. CMAJ, 188(3), E53-63. https://doi.org/10.1503/cmaj.150535