The objectives of this study are to: 1) validate a rapid, portable, cost-effective method for screening myosteatosis and sarcopenia using diagnostic ultrasound, and 2) investigate a novel approach to progressive resistance exercise involving eccentric muscle actions that will counter the local effects of myosteatosis and sarcopenia in African Americans.
The rationale for this study is the need to proactively address health disparities associated with age-related skeletal muscle dysfunction. Age-related changes in muscle may be characterized by sarcopenia (i.e., loss of muscle mass) and/or myosteatosis (i.e., excessive intramuscular adipose tissue). These changes may result in physical impairments that may be exacerbated by the lack of a formal screening and diagnosis process for older adults in standard healthcare settings. Myosteatosis may compound the effects of sarcopenia and play a significant role the age-related functional decline and higher incidence of type 2 diabetes observed in African Americans in comparison to other ethnic/racial groups. The initial phase of the study will involve the assessment of older African Americans (n = 70) to characterize muscle size and quality in comparison to a younger reference group (n = 70). Participants randomly selected from the older subject pool will be assigned to either the Eccentric Exercise Group or the Concentric Exercise Group for 12 weeks of a supervised strengthening exercise regimen.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
136
Submaximal progressive resistance exercise (PRE) using eccentric muscle actions for the knee extensors/flexors will be performed for 10 repetitions, 3 to 4 sets, twice per week for 12 weeks.
Submaximal progressive resistance exercise (PRE) using concentric muscle actions for the knee extensors/flexors will be performed for 10 repetitions, 3 to 4 sets, twice per week for 12 weeks.
Rocky Mountain Regional VA Medical Center, Aurora, CO
Aurora, Colorado, United States
University of Colorado Anschutz Medical Campus
Aurora, Colorado, United States
Howard University
Washington D.C., District of Columbia, United States
Change from Baseline in Sonographic Lean Body Mass at 3 months
US estimates of aggregate regional LBM (muscle thickness, cm), will be assessed using B-mode diagnostic US with a 13-6 megahertz (MHz) linear array transducer for morphology measures at 6 axial and appendicular sites.
Time frame: At study baseline for all subjects, and at Week 6 and 12 of the intervention period for subjects randomly assigned to an exercise group
Change from Baseline in dual-energy X-ray absorptiometry (DXA) scanning at 3 months
Participants will undergo DXA scanning in the supine position per manufacturer guidelines to estimate absolute and percentage of total lean body mass (LBM) and body fat (BF).
Time frame: At study baseline for all subjects, and at Week 12 of the intervention period for subjects randomly assigned to an exercise group
Change from Baseline in metabolic status at 3 months
A blood sample (60 cc) will be obtained after an 8-hour overnight fast: glucose and insulin levels will be assessed. Other laboratory values will be obtained such as a standard lipid profile and glycated hemoglobin (HbA1C).
Time frame: At study baseline for all subjects
Change from Baseline in intramuscular adipose tissue assessment at 3 months
Estimates of intramuscular adipose tissue (IMAT) will be obtained with magnetic resonance imaging using a whole body transmit/receive coil for T2 fat image acquisition of the thigh (dominant side) will be obtained at the mid-femur region.
Time frame: At study baseline for all subjects
Change from Baseline in strength assessment at 3 months
Grip strength will be assessed bilaterally; isometric and isokinetic knee extension/flexion torques will be obtained bilaterally using a dynamometer. Peak concentric torque (at 60 /s and 180 /s) will be obtained in a randomized fashion with subject positioning and stabilization per the manufacturer operations manual.
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Time frame: At study baseline for all subjects, and at Week 6 and 12 of the intervention period for subjects randomly assigned to an exercise group