Merit

Aging and physical inactivity are associated with changes in body composition characterized by increases in fat mass and reductions in fat-free mass, leading to increased function ability. Elderly women are particularly susceptible to disability as they have more fat mass, less skeletal muscle mass and strength and are less physically active compared to their male counterparts. The primary body composition outcomes responsible for reductions in strength and physical function are not completely established. Contemporary obesity research has focused on intermuscular adipose tissue (IMAT) and intramuscular triglycerides (IMTG). Both IMAT and IMTG are dynamic and can be altered with diet, weight loss and exercise. Importantly, muscle-associated lipids may play a larger role than appreciated with regard to muscle quality as weight loss and exercise regimens effects on IMTG may alter muscle fiber orientation, and subsequently alter the effective muscle physiological cross-sectional area (PCSA) which is proportional to the maximum muscle force.

From a public health perspective, the relative importance of “fitness” compared to “fatness” is of high clinical importance with regard to targeting interventions to ameliorate disability related to disordered body composition in the elderly. The further refinement and application of proton Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) to quantify IMTG impacts on muscle quality and the subsequent relation to clinically relevant metabolic and physical functional outcomes in the elderly is essential for elucidating mechanisms in vivo and with high translational research value.

The primary goals of the proposed research are to: a) establish the precision and sensitivity of MRI and MRS to quantify IMTG and histoarchitecture, defined as muscle quality, b) explore the relation of these muscle attributes to insulin action and muscle strength and physical function in elderly women differing in adiposity and habitual physical activity and c) assess the effect of exercise training and weight loss on these parameters. To meet this objective, fifty elderly (65–80 y) females will be recruited and blocked on adiposity (normal weight vs. obese), and normal weight women will be further blocked on physical fitness (sedentary vs. physically active) and will be assessed for muscle associated lipids and histoarchitecture using a cross-sectional design. A parallel-arm study design will also be used with the obese women from the cohort randomized to either a weight loss program induced by caloric restriction alone to elicit a reduction of 10% body weight or a weight stable exercise program for 6 months to explore the sensitivity of the MRI and MRS measures to histochemically known perturbations of muscle quality.

NDC

The overall objective of the proposed research is to determine the efficacy of a weight loss diet higher in protein, rich in dairy products including whey protein, and lower in carbohydrate (HP/LC) combined with moderate exercise to favorably impact body composition, bone health, physical function, and quality of life compared to a conventional higher carbohydrate low protein (HC/LP) diet in obese mildly frail elderly women. It is hypothesized that: a) HP/LC will attenuate reductions in bone quality as indicated by trabecular bone characteristics, attenuate reductions in muscle mass and enhance muscle quality as indicated by reductions in intermuscular adipose tissue compared to HC/LP diet; b) HP/LC diet will result in greater fat mass loss, and attenuate reductions in lean mass, bone mineral content and density compared to the HC/LP diet; c) markers of bone, anabolic hormones indicative of protein accretion and inflammatory markers will support measured fat, lean and bone mass changes in the treatment groups; and, d) although physical function and quality of life will improve in both groups, the HP/LC diet will have greater improvement in physical performance, especially in muscle strength, compared to the HC/LP diet. Lastly, the weight loss regimen will decrease levels of inflammatory markers.

Aging is associated with changes in body composition characterized by increases in fat mass and reductions in fat-free mass that leads to declines in strength, endurance, balance and mobility, and quality of life. Treatment for obesity in older persons is difficult as there are potential negative effects of weight loss on muscle and bone mass increasing risks for sarcopenia and osteoporosis. Data strongly suggest that weight loss diets with increased amounts of high quality protein (~30% of daily energy intake) enhance body and fat mass loss while attenuating lean and bone mass loss; however, no studies have examined this treatment in obese frail elderly women. To meet the stated research objective, 30 relatively healthy obese (BMI ≥ 30 kg/m2) elderly (65 – 80 y old) mildly frail females will be randomized to either a HP/LC or HC/LP dietary regimen with moderate exercise, including aerobic and resistance training, for 6 months with the goal of losing ~10% of initial body weight. Body composition and bone health will be measured by magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DXA). Blood markers of bone metabolism and anabolic hormones linked to protein accretion [cross-linked telopeptides of type I collagen, bone-specific alkaline phosphatase, parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1) and insulin] as well as inflammatory markers [C-reactive protein (CRP) and interleukin-6 (IL-6)] will be assessed to gain insight into mechanisms responsible for changes in body composition and bone. Physical performance testing will include a battery of balance and gait tests (e.g. 8 foot up and go), and muscle strength and endurance. Quality of life will be measured using the 12-Item Short Form Survey of the Medical Outcomes 36-item Short Form Survey and the Satisfaction with Life Scale.

PEER

Because of the poor long-term success in treating obesity, research efforts are targeting obesity prevention strategies. This integrated project, consisting of research, education and extension components, proposes to test the effectiveness of a peer-delivered self-efficacy-based intervention on nutrition and physical activity behaviors and weight management success in female college freshman. The first primary aim is to determine the effectiveness of a peer-delivered self efficacy-based behavioral intervention to enhance nutrition and physical activity behaviors and subsequently weight management success in female university freshman over one academic year. We hypothesize that freshmen randomized to the intervention group will be more successful in losing or maintaining weight than the control group through a combination of diet and physical activity strategies. The second primary aim is to examine the role played by social cognitive factors in changing nutrition and physical activity behaviors across one academic year. We hypothesize that self-efficacy (i.e. situational self-confidence) will have both a direct influence on behavior and an indirect effect through its influence on self-regulatory skills and outcome expectations.

This study will use a randomized controlled study design to investigate the combined effects of an exercise and nutrition intervention that is based on self-efficacy principles and delivered primarily by peer educators to reduce the risk for obesity in female college freshman over one academic year (N = 300). The control group will receive minimal interaction from the research team mimicking a typical freshman experience on the UIUC campus. Recruitment will take place in two waves (consecutive fall terms with n = 150 each). During the final year (Fall 2010) of the project, a General Education course will be offered that targets weight management and will be cross-listed in the departments of Kinesiology and Community Health and Food Science and Human Nutrition. Importantly, the discussion groups for this course will be taught by peer educators trained using the peer resources further refined with this PEER project. In addition to conventional measures of content knowledge assessed in the college classroom when obtaining class credit, personal physical activity and nutrition behaviors along with behavioral determinants (self-efficacy, self-regulatory skills and outcome expectations) will also be assessed.

VIGOR

With these changes in the aging demographics, age-related reductions in physical function are a primary public health concern. Detriments in physical function are predictive of falls, fractures, hospitalizations, cognitive decline, loss of independence and even mortality. A more comprehensive understanding of factors influencing physical function is imperative for successful aging and maintenance of independence in older adults.

Fatigue is one of the most frequently cited barriers to physical activity, and is a widespread complaint reported clinically. Older adults tend to report higher levels of fatigue, with prevalence estimates ranging up to 50%. Importantly, this age group is most susceptible to the deleterious effects of fatigue including physical inactivity, muscle weakness, and other similar health detriments to that of poor physical function outlined above. Furthermore, older individuals have the added challenge of combating this fatigue to complete their activities of daily living, preserve muscle mass, maintain function, and remain independent.

Two of the underlying factors contributing to loss of muscle mass, muscle weakness and fatigue appear to be adiposity status and systemic low-grade inflammation, both of which is also predictive of cardiovascular disease and diabetes. Both adiposity and physical inactivity contribute to this inflammatory profile, however the effect of both of these, and their interaction, on fatigue is not well known. Identification and understanding of the factors that influence fatigue are a major public health priority.