Abrar A. QURESHI and his team sought to evaluate the association between physical activity and psoriasis, a common inflammatory skin disease, in a cohort of women in the United States. They also assessed the association between the type of physical activity, for example, walking or vigorous exercise, and the risk of psoriasis. The population studied included 86,655 American nurses who reported having been diagnosed with psoriasis and who completed detailed questionnaires about their physical activity in 1991, 1997, and 2001.
After adjusting for age, smoking, and alcohol consumption, an increase in physical activity was inversely associated with the risk of psoriasis. The quintile of women who were the most physically active had a lower relative risk (RR) of psoriasis (0.72) than the least active quintile (1.06). Walking was not associated with the risk of psoriasis. Furthermore, in a subset of 550 confirmed psoriasis cases, there was a greater reduction in the risk of psoriasis associated with intense physical activity (0.64).
It is biologically plausible that intense activity could modulate the state of chronic inflammation or immune activation that predisposes to psoriasis. An overexpression of pro-inflammatory cytokines compared to anti-inflammatory molecules plays a significant role in the pathogenesis of psoriasis, and conditions marked by increased chronic inflammation, such as obesity, can heighten the risk of psoriasis. It is known that physical activity decreases this chronic inflammation and specifically reduces the levels of pro-inflammatory mediators, such as the TNF-α, IL-6, and leptin. Physical activity can increase the levels of anti-inflammatory cytokines, including adiponectin. Moreover, physically active women have lower levels of C-reactive protein (CRP), an inflammatory marker.
Another significant finding from the study is that walking and intense physical activity do not confer similar reductions in the risk of psoriasis; only intense activity reduces it. This observation can be explained by the more substantial effects of moderate to vigorous activity on systemic inflammation. In an interventional trial, a 12-week program of low to moderate intensity aerobic exercises did not alter the serum levels of TNF-α, IL-6, and CRP in obese women. However, vigorous intensity aerobic exercises may reduce the levels of inflammatory markers and thus lower the risk of developing inflammatory skin conditions such as psoriasis.
However, further studies on the subject are necessary to confirm these results.