Objective Excess weight is a known risk factor for functional limitation and common in adults with knee osteoarthritis (OA). We asked to what extent high waist circumference was linked with developing difficulty with walking speed and distance over 4 years in adults with or at risk of knee OA. Method Using data from the Osteoarthritis Initiative, we employed WHO categories for Body Mass Index (BMI) and waist circumference (small/medium and large). Difficulty with speed was defined by slow gait: < 1.2 m/s during a 20-meter walk, and difficulty with distance was defined by an inability to walk 400 meters. We calculated risk ratios (RR) to examine the likelihood of developing difficulty with distance and speed using obesity and waist circumference as predictors with RRs adjusted for potential confounders (i.e., age, sex, race, education, physical activity, and OA status). Results Participants with obesity and large waists were 2.2 times more likely to have difficulty with speed at 4 years compared to healthy weight and small/medium waisted participants (Adjusted RR 2.2 [95% Confidence interval (CI) 1.6, 3.1], P < .0001). Participants with obesity and a large waist circumference had 2.4 times the risk of developing the inability to walk 400 meters compared with those with a healthy BMI and small/medium waist circumference (Adjusted RR 0.9 [95% CI 1.6, 3.7], P < .0001). Conclusions Waist circumference may be a main risk factor for developing difficulty with speed in adults with or at risk of knee OA.

Quadriceps strength may protect against knee osteoarthritis (OA), but muscle activity is a major determinant of forces at the hand joints. Gripping objects is a common task during which high muscular forces are sustained, particularly at the proximal hand joints (metacarpophalangeal (MCP) joints and thumb base). The association between maximal grip strength and incident OA at different hand joints was examined in a longitudinal study of radiographic hand OA. Subjects with higher maximal grip strength were at increased risk for development of OA in the proximal interphalangeal (PIP) joints, MCP and thumb base joints in men; and in the MCP in women. No association was found between maximal grip strength and incident distal interphalangeal (DIP) joints OA in men or women. The conclusion is that increased grip strength, which is the major force of loading across proximal hand joints, increases the risk of OA in those joints.