Autoimmune disorders, physical activity, and training, with particular reference to rheumatoid arthritis.

Rheumatoid arthritis arises from a reaction of the immune system to normal body components, sometimes triggered by bacterial or viral infection. The synovia of affected joints are infiltrated by CD4+, CD19-, and plasma cells. The synovial fluid shows a sterile inflammation, with high neutrophil counts and increased concentrations of proinflammatory cytokines (particularly IL-1, IL-8, TNF-alpha and JFN-gamma). The plasma shows increased CD4+ counts and a pro-inflammatory shift in T cell populations with high titers of rheumatoid factors. Traditional treatment has included rest of the affected part, which can cause a reduction of physical condition. However, exercise induces changes in circulating immune function (including a decrease of CD4+ count) that would appear helpful in regulating inflammation. Further, there is evidence that patients can tolerate a program of regular moderate aerobic exercise. Moreover, empirical data suggest that such a prescription substantially enhances physical performance, without exacerbating either clinical or immunological markers of the disease process.