Effects of a hydrotherapy program on baroreflex sensitivity in women with fibromyalgia syndrome

Baroreflex dysfunction has been demonstrated in fibromyalgia syndrome (FMS). However, there are few studies evaluating the effectiveness of hydrotherapy programs on cardiovascular autonomic control in this population. This study evaluates the effects of a 16-week hydrotherapy program on baroreflex sensitivity (BRS) in women with FMS. Eight women with FMS took part in the study. The electrocardiogram, non-invasive finger blood pressure and respiratory activity were continuously recorded for all participants during 15 min in supine and 15 min in orthostatic (active standing) positions, before and after a 16-week hydrotherapy program (Post16). The BRS was estimated via cross-spectral analysis, computed as the square root of the ratio of the low frequency (LF) band power of heart period on the LF power of systolic arterial pressure (α_LF). The hydrotherapy program comprised 32 sessions of 45 min of pool exercises twice a week, for 16 weeks. At baseline there was no significant difference for the α_LF index between supine and orthostatic positions (p > 0.05). At Post16, there was a significant decrease of the α_LF during orthostatic stimulus compared to the supine position (p < 0.05). There was no significant difference between baseline and Post16 for α_LF in supine position (p > 0.05). However, the α_LF was lower at Post16 during orthostatic posture compared to the baseline (p < 0.05). The variation of α_LF between supine and orthostatic postures (Δα_LF) was higher at Post16, compared to the baseline (Δα_LF baseline: -1.7 ± 3.5; Post16: -6.9 ± 5.7; p < 0.05). A 16-week hydrotherapy program improved the cardiac baroreflex control response to the orthostatic stimulus in women with FMS.