Objective. The Arthritis, Diet, and Activity Promotion Trial (ADAPT) was a randomized, single-blind clinical trial lasting 18 months that was designed to determine whether long-term exercise and dietary weight loss are more effective, either separately or in combination, than usual care in improving physical function, pain, and mobility in older overweight and obese adults with knee osteoarthritis (OA).Methods. Three hundred sixteen communitydwelling overweight and obese adults ages 60 years and older, with a body mass index of >28 kg/m 2 , knee pain, radiographic evidence of knee OA, and self-reported physical disability, were randomized into healthy lifestyle (control), diet only, exercise only, and diet plus exercise groups. The primary outcome was self-reported physical function as measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcomes included weight loss, 6-minute walk distance, stair-climb time, WOMAC pain and stiffness scores, and joint space width.Results. Of the 316 randomized participants, 252 (80%) completed the study. Adherence was as follows: for healthy lifestyle, 73%; for diet only, 72%; for exercise only, 60%; and for diet plus exercise, 64%. In the diet plus exercise group, significant improvements in selfreported physical function (P < 0.05), 6-minute walk distance (P < 0.05), stair-climb time (P < 0.05), and knee pain (P < 0.05) relative to the healthy lifestyle group were observed. In the exercise group, a significant improvement in the 6-minute walk distance (P < 0.05) was observed. The diet-only group was not significantly different from the healthy lifestyle group for any of the functional or mobility measures. The weight-loss groups lost significantly (P < 0.05) more body weight (for diet, 4.9%; for diet plus exercise, 5.7%) than did the healthy lifestyle group (1.2%). Finally, changes in joint space width were not different between the groups.Conclusion. The combination of modest weight loss plus moderate exercise provides better overall improvements in self-reported measures of function and pain and in performance measures of mobility in older overweight and obese adults with knee OA compared with either intervention alone.Arthritis is the leading cause of physical disability among older adults, affecting more than 70 million Americans, of whom the majority are women (1-4). The joint damage and chronic pain from osteoarthritis (OA), the most common form of arthritis, lead to muscle atrophy, decreased mobility, poor balance, and, eventually, physical disability (5-8). Traditional therapies include pharmacologic, surgical, and exercise interventions. Pharmacologic therapy includes the use of antiinflammatory medications that have potentially serious long-term side effects (9,10). Recent evidence also casts doubt as to the effectiveness of arthroscopic surgery for adults with mild to moderate knee OA (11).

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Objective The prevalence of symptomatic knee osteoarthritis (OA) has been increasing over the past several decades in the United States concurrent with an aging population and the growing obesity epidemic. We quantify the impact of these factors on the number of persons with symptomatic knee OA in the first decades of 21st century. Methods We calculated prevalence of clinically diagnosed symptomatic knee OA from the National Health Interview Survey 2007–08 and derived the proportion with advanced disease (Kellgren-Lawrence grades 3–4) using the Osteoarthritis Policy Model, a validated simulation model of knee OA. Incorporating contemporary obesity rates and population estimates, we calculated the number of persons living with symptomatic knee OA. Results We estimate that about fourteen million persons had symptomatic knee OA, with advanced OA comprising over half of those cases. This includes over three million African American, Hispanic, and other racial/ethnic minorities. Adults under 45 years of age represented nearly two million cases of symptomatic knee OA and individuals between 45 and 65 years of age six million more. Conclusion Over half of all persons with symptomatic knee OA are younger than 65 years of age. As many of these younger persons will live for three decades or more, there is substantially more time for greater disability to occur and policymakers should anticipate healthcare utilization for knee OA to increase further in upcoming decades. These data emphasize the need for the deployment of innovative prevention and treatment strategies for knee OA, especially among younger persons.

Objective. To determine the relationship between change in body mass and knee-joint moments and forces during walking in overweight and obese older adults with knee osteoarthritis (OA) following an 18-month clinical trial of diet and exercise.Methods. Data were obtained from 142 sedentary, overweight, and obese older adults with self-reported disability and radiographic evidence of knee OA who underwent 3-dimensional gait analysis. Gait kinetic outcome variables included peak knee-joint forces and peak internal knee-joint moments. Mixed regression models were created to predict followup kinetic values, using followup body mass as the primary explanatory variable. Baseline body mass was used as a covariate, and thus followup body mass was a surrogate measure for change in body mass (i.e., weight loss).Results. There was a significant direct association between followup body mass and peak followup values of compressive force (P ‫؍‬ 0.001), resultant force (P ‫؍‬ 0.002), abduction moment (P ‫؍‬ 0.03), and medial rotation moment (P ‫؍‬ 0.02). A weight reduction of 9.8N (1 kg) was associated with reductions of 40.6N and 38.7N in compressive and resultant forces, respectively. Thus, each weight-loss unit was associated with an ϳ4-unit reduction in knee-joint forces. In addition, a reduction in body weight of 9.8N (1 kg) was associated with a 1.4% reduction (0.496 Nm) in knee abduction moment. Conclusion. Our results indicate that each poundof weight lost will result in a 4-fold reduction in the load exerted on the knee per step during daily activities. Accumulated over thousands of steps per day, a reduction of this magnitude would appear to be clinically meaningful.The precise etiology of osteoarthritis (OA) is unknown; however, several risk factors have been identified, including age (1,2), female sex (3), and both occupational (4,5) and sports-related joint stress (6-9). The most important modifiable risk factor for the development and progression of OA is obesity (1,10-17). Weight loss reduces the risk of symptomatic knee OA (13), and for obese patients with knee OA, weight loss and exercise are recommended by both the American College of Rheumatology and the European League Against Rheumatism (18,19). We have shown that an average weight loss of 5% over 18 months in overweight and obese adults with knee OA results in an 18% improvement in function. When dietary changes are combined with exercise, function improves 24% and is accompanied by a significant improvement in mobility (20).Although obesity is strongly associated with knee OA, some obese but otherwise healthy adults adapt to their excessive weight and subsequently reduce kneejoint torques and possibly knee-joint forces during walking (21). In other obese adults, however, excessive biomechanical joint stress represents one possible pathway for the pathogenesis and progression of knee OA. We hypothesized a significant and direct relationship between weight loss and attenuation of knee-joint forces and moments during walking in overweight and obese older adu...

These findings provide evidence from a randomized controlled trial that a dietary intervention designed to elicit weight loss reduces overall inflammation in older, obese persons. Additional studies are needed to assess the effects of different modes and intensities of exercise on inflammation.

Weight loss can be achieved and sustained over a 6-month period in a cohort of older obese persons with osteoarthritis of the knee through a dietary and exercise intervention. Both exercise and combined weight loss and exercise regimens lead to improvements in pain, disability, and performance. Moreover, the trends in the biomechanical data suggest that exercise combined with diet may have an additional benefit in improved gait compared with exercise alone. A larger study is indicated to determine if weight loss provides additional benefits to exercise alone in this patient population.

Objective: Physical function and body composition in older obese adults with knee osteoarthritis (OA) were examined after intensive weight loss. Research Methods and Procedures:Older obese adults (n ϭ 87; Ն60 years; BMI Ն 30.0 kg/m 2 ) with symptomatic knee OA and difficulty with daily activities were recruited for a 6-month trial. Participants were randomized into either a weight stable (WS) or weight loss (WL) program. Participants in WL (10% weight loss goal) were prescribed a 1000 kcal/d energy deficit diet with exercise 3 d/wk. WS participants attended health information sessions. Body composition and physical function (Western Ontario and McMaster University Osteoarthritis Index, 6-minute walking distance, and stair climb time) were assessed at baseline and 6 months. Statistical analysis included univariate analysis of covariance on 6-month measurements using baseline values as covariates. Associations between physical function and body composition were performed.Results: Body weight decreased 8.7 Ϯ 0.8% in WL and 0.0 Ϯ 0.7% in WS. Body fat and fat-free mass were lower for WL than WS at 6 months (estimated means: fat ϭ 38.1 Ϯ 0.4% vs. 40.9 Ϯ 0.4%, respectively; fat-free mass ϭ 56.7 Ϯ 0.4 vs. 58.8 Ϯ 0.4 kg, respectively). WL had better function than WS, with lower Western Ontario and McMaster University Osteoarthritis Index scores, greater 6-minute walk distance, and faster stair climb time (p Ͻ 0.05). Changes in function were associated with weight loss in the entire cohort. Discussion: An intensive weight loss intervention incorporating energy deficit diet and exercise training improves physical function in older obese adults with knee OA. Greater improvements in function were observed in those with the most weight loss.

With the exception of shoe mileage, which is likely a response to rather than a risk factor for AKP, these results should prove useful to clinicians in identifying runners at risk for anterior knee pain.