Data from large randomized, controlled trials (RCTs) and systematic reviews of the literature indicate that exercise provides small to modest benefits (effect sizes ranging from 0.2 to 0.4) for pain relief, improved function, and reduced disability. However, details on the frequency, intensity, duration, and type of exercise (aerobic, flexibility, dynamic or static strengthening, balance activities) are not always specified. Helmark and colleagues reported that in a group of women with knee OA, exercise increased both intraarticular and perisynovial concentrations of interleukin-10, an antiinflammatory cytokine that protects chondrocytes (cartilage cells) and may be responsible for the benefits for OA seen with exercise.