No adverse physiological responses to infrared whole body hyperthermia in patients with rheumatoid arthritis and ankylosing spondylitis compared to healthy subjects.

PURPOSE: Since about ten years a new modality for whole body hyperthermia, a compact and userfriendlyinfrared (IR) 'sauna' has become available. Patients with musculoskeletal disorders report positive effects.RELEVANCE: Until now hardly any research was done in this field. Therefore in this study the short-termphysiological and clinical effects in healthy subjects and patients with Rheumatoid Arthritis (RA) andAnkylosing Spondylitis (AS) were investigated. SUBJECTS: 17 RA patients (3 male, 14 female), 19 AS patients (12 male, 7 female) and 21 healthy subjects (11 male, 10 female) with a mean age (sd) of 47 (13), 45 (10) and 45 (7) years respectively were included in the study.METHODS AND MATERIALS: Patients with RA or AS and healthy subjects were treated with whole-body hyperthermia by means of a 30 minutes stay in a IR sauna cabin at an adjusted temperature of 55°C. Before and directly after the sauna treatment in both RA and AS patient groups pain and stiffness and were measured on a 10 centimetres Visual Analogue Scale. Besides that in all groups body weight was measured before and after treatment. Additionally during the treatment heart rate, systolic and diastolic blood pressure, skin surface and core temperature were continuously monitored. Also general wellbeing during and after treatment was investigated. RESULTS: Pain and stiffness improved significantly duringtreatment; mean between 40% and 60%. The mean weight loss during treatment due to transpiration was significant (p<0.001) in all groups, but it was significantly higher (p<0.001) in healthy subjects (-0.5 kg) than in patients (both RA and AS -0.3 kg). During treatment mean heart rate, skin and core temperature increased significantly p<,0.001) in all groups, while blood pressures showed small but significant declines. No significant differences between groups were observed. On average all subjects felt comfortable during and especially after treatment. CONCLUSION: Infra red whole body hyperthermia has statistically significant positive direct effects upon pain and stiffness in RA as well as in AS patients. Looking at the physiological effects, RA and AS patients do not respond differently from age and gender matched healthy controls.