Ruijgt, Twan M, Slaghekke, Anouk, Ellens, Anneke et al. · Sports medicine (Auckland, N.Z.) · 2026 · DOI
This observational study measured heart rate variability (a marker of nerve system balance) in 121 long COVID patients and 21 healthy controls using wearable devices over multiple days. Researchers observed that long COVID patients had lower heart rate variability during daily activities and sleep, and their heart rate variability remained reduced for 24 hours after exercise, particularly at intensities above their aerobic threshold. The findings suggest wearables may help patients recognise when they are overexerting, though the study does not yet establish whether this monitoring prevents post-exertional malaise.
By analogy, this study may be relevant to ME/CFS research, as autonomic dysfunction and PEM are central features of both conditions. Continuous HRV monitoring via wearables offers a non-invasive, objective tool to track autonomic recovery post-exertion, which could help researchers and patients identify personalised exercise thresholds. However, relevance to ME/CFS is unclear until similar studies are conducted in ME/CFS cohorts using standardised case definitions.
This observational study does not establish that autonomic dysfunction causes PEM, nor does it prove that wearable HRV monitoring prevents or treats post-exertional malaise. It does not measure PEM directly, does not establish VT1 as a validated clinical threshold for managing exertion in long COVID, and does not generalise beyond the 121 patients studied. Findings from long COVID may not transfer to ME/CFS without direct replication in an ME/CFS cohort.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Ruijgt, Twan M, Slaghekke, Anouk, Ellens, Anneke, Janssen, Kasper W, & Wüst, Rob C I (2026). Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.. Sports medicine (Auckland, N.Z.). https://doi.org/10.1007/s40279-026-02487-4
BibTeX
@article{mecfsatlas-ruijgt-2026-wearable-heart,
author = {Ruijgt, Twan M and Slaghekke, Anouk and Ellens, Anneke and Janssen, Kasper W and Wüst, Rob C I},
title = {Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.},
journal = {Sports medicine (Auckland, N.Z.)},
year = {2026},
doi = {10.1007/s40279-026-02487-4},
note = {PubMed: 42501245},
url = {https://www.mecfsatlas.com/evidence/ruijgt-2026-wearable-heart},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-07-27. https://www.mecfsatlas.com/evidence/ruijgt-2026-wearable-heart
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