This Career Development Award proposal, Detection and Treatment of Sarcopenia and Myosteatosis in Older African Americans, was submitted in association with the VA Historically Black College and University (HBCU) Research Scientist Training Program. This proposed study and training program will be jointly conducted at VA and HBCU facilities under the direction of Dr. Michael Harris-Love with project mentorship provided by Dr. Marc Blackman (DC VAMC) and Dr. Vernon Bond (Howard University). The rationale for this study is the high prevalence of excessive intramuscular fat tissue (i.e., myosteatosis) in African Americans, which may worsen the age-related functional decline associated with sarcopenia (i.e., loss of muscle mass) and contribute to a higher incidence of type 2 diabetes. Health disparities associated with age-related skeletal muscle dysfunction may be exacerbated by the lack of a formal screening and diagnosis process for older adults in standard healthcare settings. The objectives of this proposal are to validate a rapid, portable, cost-effective method for screening myosteatosis and sarcopenia using diagnostic ultrasound, and develop a novel approach to progressive resistance exercise involving eccentric muscle actions (i.e., force produced when muscle lengthens) that will counter the effects of myosteatosis and sarcopenia. These objectives will be addressed through a prospective clinical study with a projected enrollment of 140 African American participants (young reference group, 18-30 y.o.; young-old group, 65-84.9 y.o.; 50% female; 70 participants in each group) for a joint VA and HBCU clinical study conducted over a 5-year period. The study is comprised of 2 projects: Project 1: Determine if ultrasound can provide a valid measure of muscle mass and myosteatosis. Muscle mass will be estimated via dual energy X-ray absorptiometry (DXA) and myosteatosis will be measured via computerized tomography (CT) scanning. The ultrasound estimates of muscle mass and myosteatosis will be analyzed for their relationship with the corresponding DXA and CT scan values. The contemporary diagnosis of sarcopenia is a loss of muscle mass with diminished strength or a loss of function. Therefore, 'myosteatosis' will be added to 'muscle mass' as a predictor variable of muscle strength and functional performance to determine if estimates of both muscle mass and muscle tissue composition improve the sarcopenia diagnostic model in African Americans. Project 2: Determine the efficacy of eccentric exercise to mitigate myosteatosis, and increase muscle mass and strength values. Eccentric muscle actions are infrequently used for therapeutic exercise, yet they yield higher forces at a lower metabolic cost in comparison to the concentric muscle actions that characterize conventional exercise. These qualities make eccentric exercise ideal for older adults. Participants in the young- old group will be randomized into eccentric exercise and conventional home exercise groups to engage in a 12-week resistance training regimen. Peak knee extensor/flexor torque and assessments of myosteatosis and muscle mass will be assessed pre- and post-training, and compared between both groups. Completion of this VA HBCU Research Scientist Training Program project will improve our understanding of age-related muscle changes in African Americans, yield tangible outcomes such as the development of a non- invasive, portable sarcopenia and myosteatosis screening method, and provide an innovative intervention approach suitable for older adults with muscle dysfunction.
This purpose of this project is to improve the detection and treatment of age-related changes in muscle mass and quality in older African Americans. Muscle abnormalities in older adults often remain undetected until the incidence of an injury or a disabling event. The assessment of muscle wasting only after the manifestation of weakness is an inadequate screening model. Moreover, health disparities in African Americans concerning type 2 diabetes and age-related declines in functional performance may be linked to changes in muscle quality. Therefore, the objectives of this VA Historically Black College and University career development project are to: 1) develop a rapid, portable, cost-effective method for assessing muscle mass and quality using ultrasound imaging, and 2) demonstrate how an innovative form of strength training that is appropriate for older adults can reverse age-related changes in muscle mass and quality. Completion of this project will aid the identification of risk factors for age-related muscle wastig and expand the approach to exercise-based interventions.
