The effects of warm water immersion on blood pressure, heart rate and heart rate variability in people with chronic fatigue syndrome.
Romy Parker, Zeenath Higgins, Zandiswa N P Mlombile and 2 others
PMID 30214947WHAT IT FOUND
Blood pressure did not differ between people with chronic fatigue syndrome and controls before, during, or after warm-water immersion.
Heart rate was higher in the CFS group after immersion, and heart-rhythm variation was lower only before immersion. The study was too small to show benefit.
Key findings
01Systolic and diastolic blood pressure did not differ between the CFS and control groups before, during, or after immersion.
02After immersion, controls had a lower heart rate than people with CFS (78 [60-86] vs 86 [65-112]; p = 0.03).
03Before immersion, heart rate variability was higher in controls than in people with CFS (73 [55-74] vs 63 [50-70]; p = 0.04), and the groups did not differ during or after immersion.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 18 participants were studied, with fewer than 10 in each group, so the study was underpowered and its results may not generalise. Recruitment used a convenience sample and matched controls, not random allocation, so baseline differences may remain. The paper describes blinding only during data analysis. Measurements were taken over a 5-hour period, so circadian variation may have influenced blood pressure results. The study measured only one 5-minute standing immersion, not hydrotherapy exercise or longer treatment programmes. The authors noted that height differences between groups may have influenced the results. The authors could not draw conclusions about blood pressure because of non-significant between-group differences and data distribution.
The easy way to misread this
Do not conclude that warm-water immersion treats chronic fatigue syndrome or normalises heart rhythm variation. The study had only 18 participants, used a convenience sample without randomisation, and showed no significant change in heart rate variability over time in either group.