Although aerobic exercise training (AT) has been the cornerstone of rehabilitation for patients with CVD or MetS, experts agree that with the escalating problem of obesity, prevention programs in this area need to target weight loss (WL) as well. This is reinforced by recent research of our own showing that obesity is a major risk factor for physical disability among older adults. From a translational perspective, clinical researchers have recommended that effective community partnerships are needed to deliver such programs. In response to this call, the investigators have recently completed a translational study funded by NHLBI, the Cooperative Lifestyle Intervention Program (CLIP). In this investigation, 288 obese, older adults with CVD or MetS were randomized to a successful aging control treatment (SA), AT, or AT+WL for 18-months. The primary outcome was mobility disability, assessed by performance on the 400 m Walk Test (400MWT), and our staff co-delivered the interventions with agents from 3 counties within the community infrastructure of North Carolina Cooperative Extension Centers. Whereas mobility improved significantly in the AT group compared to SA, AT+WL was superior to either SA or AT.
Building on CLIP, the investigators now propose to increase the translational significance of our interventions by having them delivered exclusively by community partners with our staff as "trainers and advisers" for desired behavior change. In addition, this study will provide the first large scale randomized controlled clinical trial to evaluate the effects of diet-induced weight loss (WL) on mobility in obese, older adults with CVD or the MetS as compared to WL combined with physical activity. The dual primary outcomes will be the 400MWT and muscle strength. Because uncertainty exists about the best approach for promoting WL in older adults due to concerns with the loss of lean mass, the design also permits a contrast between AT+WL and resistance exercise training (RT)+WL on muscle strength. Consistent with CLIP, our WL intervention will target a protein intake of 0.8 g∙kg body mass-1∙d-1. Reasons to consider RT+WL for older adults include: 1) the central role of muscle loss and decline in strength in mobility disability; 2) the underappreciated role of RT in cardiovascular health; 3) the influence of muscle mass on both resting and total energy expenditure as well as fat mass and bone health; and 5) the potential value of RT for improving mobility on tasks that depend heavily on the vertical movement of the center of mass (e.g., stair climbing). Eves and Plotnikoff22 have emphasized the importance of RT in older diseased populations and stated that "the investigators need to discover practical, sustainable, and economically viable ways to safely implement RT at the population level." To accomplish our goals, the investigators have created a community partnership with the YMCA, using 4 sites in Forsyth County, NC. One of the sites serves a large African American population. The investigators are moving this project from Cooperative Extension Centers to the YMCA because the former have neither the equipment nor the personnel necessary to independently train and monitor RT or AT.
