Fig. 1.

Progressive relationship among obesity, osteoarthritis, and physical inactivity. Obesity is an independent risk factor for osteoarthritis. The mechanisms responsible for this link are not completely understood but are thought to involve altered biomechanical loading and metabolic inflammation associated with excess adipose tissue and lipids. Osteoarthritis pain increases sedentary behavior and is associated with psychosocial and physical disability. Physical inactivity is an independent risk factor for inflammation due to the reduced expression of systemic and cellular anti-inflammatory mediators. Physiologic cyclic loading of cartilage tissue has been shown to reduce the expression of pro-inflammatory mediators and decrease cytokine-induced extracellular matrix degradation. Physical inactivity reduces daily energy expenditure thereby promoting weight gain and continuation of the cycle. Emerging evidence indicates that osteoarthritis likely impedes the management of chronic metabolic diseases associated with aging, such as obesity, diabetes, and heart disease, because of its negative impact on physical activity.