Spa
therapy represents a popular treatment for many
rheumatic diseases. The mechanisms by which immersion in
mineral or thermal water or the application of mud alleviates suffering in
rheumatic diseases are not fully understood. The net benefit is probably the result of a combination of factors, with mechanical, thermal and chemical effects among the most prominent ones. Buoyancy, immersion, resistance and temperature all play important roles. According to the gate theory,
pain relief may be due to the pressure and temperature of the water on skin; hot stimuli may influence muscle tone and
pain intensity, helping to reduce
muscle spasm and to increase the pain threshold.
Mud-bath therapy increases plasma β-
endorphin levels and secretion of
corticotrophin,
cortisol,
growth hormone and
prolactin. It has recently been demonstrated that thermal
mud-pack therapy induces a reduction in the circulating levels of
prostaglandin E2 (
PGE2),
leukotriene B4 (
LTB4), interleukin-1β (IL-1β) and tumour
necrosis factor-α (TNF-α), important
mediators of inflammation and
pain. Spa
therapy has been found to cause an increase in
insulin-like growth factor-1 (IGF1), which stimulates cartilage metabolism, and
transforming growth factor-β (TGF-β). There is also evidence of the positive action of
mud-packs and thermal
baths on the
oxidant/
antioxidant system, with a reduction in the release of reactive
oxygen (ROS) and
nitrogen (RNS) species. Overall, thermal stress has an immunosuppressive effect. Many other non-specific factors may also contribute to the beneficial effects observed after spa
therapy in some
rheumatic diseases, including effects on cardiovascular risk factors, and changes in the environment, pleasant surroundings and the absence of work duties.