Key result
Long COVID is linked to lower sleep HRV and delayed autonomic recovery post-exercise versus controls.
Why the study?
Patients with long COVID experience fatigue, autonomic dysfunction, and post-exertional malaise. This study aimed to use continuous multi-day HRV recordings to monitor overexertion and evaluate autonomic function.
Does continuous wearable HRV monitoring detect autonomic dysfunction and delayed recovery after exercise in patients with long COVID compared to healthy controls?
Observational (n=142)
No
Does continuous wearable HRV monitoring detect autonomic dysfunction and delayed recovery after exercise in patients with long COVID compared to healthy controls?
Mean Difference: -8.82 (95% CI -16.58–-1.06)
p-value: p=0.027
Continuous HRV monitoring via wearables reveals autonomic dysfunction and delayed recovery after exercise near or above VT1 in long COVID patients, suggesting its utility for pacing and managing post-exertional malaise.
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“But then why did they not property evaluate if patients had ME according to CC criteria? If it's real PENE/PEM they must have - and the study would be more meaningful than with a vague “long covid”. Also it seems very random. Of course HRV is lower with a chronic disease - I'm pretty sure it would also be for people who have a cold (and attempt exercise), have cancer, or anything else that messes with your system really.”
“The conclusion is of course a bit iffy because it implies all of LC experiences PEM, which… sigh. Interesting findings nonetheless though!”
“The paper notes that HRV varies with sex and age. It says that the control group was matched on sex and age, which is great, but there was a higher percentage of males in the control group (47.6% versus 31.0% - surprisingly, this was reported with a p value indicating it was not a statistically significant difference, but it seems like an important difference). There was a significant difference in BMI (23.1 for the controls versus 25.7).”
Indicates autonomic dysfunction in long COVID; hypothesis-generating for HRV monitoring to mitigate PEM.
Objectives Patients with long coronavirus disease (COVID) experience disabling fatigue, autonomic dysfunction, reduced exercise capacity and post-exertional malaise (PEM). Heart rate variability (HRV) can evaluate autonomic function and monitor overexertion, potentially helping to mitigate PEM. This study aimed to use continuous multi-day HRV recordings to monitor overexertion and study autonomic function in long COVID. Method Heart rate and HRV were continuously measured in 121 patients with long COVID (43 ± 11 years, 32% male) and 21 healthy controls (42 ± 13 years, 48% male), with daily life activities tracked in a logbook. Participants underwent a (sub)maximal cardiopulmonary exercise test to determine heart rate at the first ventilatory threshold (VT1) to study HRV responses to exercise at different intensities. Results and Discussion HRV was lower in patients with long COVID compared with healthy controls during various daily activities and sleep ( p = 0.027). Across all exercise intensities surrounding the VT1, HRV remained lower for 24 h in patients compared with controls ( p = 0.010). Nighttime HRV decreased with intense exercise and longer durations in patients with long COVID ( p = 0.018), indicative of exercise-induced diurnal disturbances of the autonomic nervous system in long COVID. Conclusion Heart rate variability, assessed by wearables, suggests autonomic dysfunction in patients with long COVID. The delayed recovery of the sympathovagal balance after exercise close to and above VT1, suggests that the risk of PEM rises above VT1. Application These results confirm the applicability of wearables to assess autonomic function and manage overexertion in patients with long COVID.
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Ruijgt et al. (2026) conducted an observational in Long COVID (n=142). Long COVID vs. Healthy controls was evaluated on Heart rate variability (RMSSD) during sleep (MD -8.82, 95% CI -16.58 to -1.06, p=0.027). Patients with long COVID exhibited significantly lower heart rate variability during sleep (MD -8.82) and delayed autonomic recovery for 24 hours post-exercise compared to healthy controls.
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