Impact of spa therapy on physical activity, sleep and heart rate variability among individuals with fibromyalgia: Results of an ancillary study

Spa therapy is recommended to manage symptoms of fibromyalgia, but the physiological mechanisms underlying this improvement have been poorly studied. In an original study, we explored the effect of a 3-week rheumatology spa treatment for fibromyalgia patients on quality of life and with a symptom severity questionnaire. We present here the results of an ancillary study which explored three secondary criteria using objective measurement methods: diurnal actimetry for physical activity analysis, nocturnal actimetry for sleep analysis and heart rate variability. Eighty-three fibromyalgia patients were randomized to participate in an immediate 3-week rheumatological spa therapy, either a start within 6 weeks after inclusion (interventional group, n = 39) or a delayed, start 6 months after inclusion (control group, n = 44). Patients were asked to wear an actimeter (n = 56) to assess diurnal physical activity and sleep quality and a 24-h Holter ECG (n = 60) to assess nocturnal heart rate variability at baseline, 3 months and 6 months after inclusion. Time spent in sedentary and light physical activity was reduced to similar to 30 min at 6 months in the interventional group (P = 0.027). Sleep quality and heart rate variability were not improved. Spa therapy made it possible to reduce sedentary activities in patients' daily life for up to 6 months afterwards, concomitant with the improvement in quality of life, pain and fatigue as highlighted in the original Thermalgi study.