The effects of warm water immersion on blood pressure, heart rate and heart rate variability in people with chronic fatigue syndrome.
Parker, Romy, Higgins, Zeenath, Mlombile, Zandiswa N P et al. · The South African journal of physiotherapy · 2018 · DOI
Quick Summary
This study looked at how warm water bathing affects heart function in people with ME/CFS compared to healthy people. Researchers found that people with ME/CFS had less stable heart rate patterns before entering warm water, but this improved during the water immersion. The heart rate stayed slightly elevated in the ME/CFS group even after leaving the water. Overall, warm water immersion appeared safe and may help with managing ME/CFS symptoms.
Why It Matters
Understanding how ME/CFS patients respond to thermal stress is critical for evaluating hydrotherapy as a potential treatment, since autonomic dysregulation is a hallmark feature of the condition. This study provides preliminary safety data and suggests warm water immersion may temporarily improve heart rate variability in ME/CFS patients, which could inform therapeutic protocols. The findings help distinguish ME/CFS cardiovascular responses from healthy controls.
Observed Findings
CFS participants had significantly lower baseline HRV (63 [50-70]) compared to healthy controls (73 [55-74]; p=0.04), suggesting autonomic dysregulation at rest.
HRV in CFS participants improved to similar levels as controls during warm water immersion.
No significant differences in blood pressure between groups were reported.
Warm water immersion did not trigger adverse events in either group.
Inferred Conclusions
Baseline HRV abnormalities in CFS reflect underlying autonomic dysregulation.
Warm water immersion temporarily normalizes HRV in CFS patients, suggesting the parasympathetic nervous system can be activated under thermal stress.
Reduced post-immersion heart rate recovery in CFS may indicate impaired vagal reactivation, a marker of autonomic dysfunction.
Warm water immersion appears safe as a potential therapeutic modality for CFS.
Remaining Questions
Do repeated warm water immersion sessions produce sustained improvements in autonomic function, or do benefits diminish over time?
What This Study Does Not Prove
This study does not prove that warm water immersion is an effective long-term treatment for ME/CFS—it only establishes acute responses during a single session. The small sample size (nine per group) limits generalizability, and the study does not assess whether these temporary improvements translate to functional benefits or whether repeated immersion is safe for all ME/CFS patients. The findings are correlational and do not establish mechanistic explanations for the observed differences.
Tags
Symptom:Orthostatic IntoleranceFatigue
Biomarker:Blood Biomarker
Method Flag:Weak Case DefinitionSmall SampleExploratory Only
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 →