Muscle wasting and weakness are prevalent after forced inactivity and bedrest. Unfortunately, bedrest is an inherent aspect of recovery from major orthopedic surgery, serious injury, or prolonged illness. The inherent loss of lean body mass (LBM) with inactivity is associated with increased recovery time and increased morbidity. Due to the greater prevalence of major orthopedic operations and serious illness, older individuals are at an increased risk for morbidity and mortality associated with extended periods of forced inactivity when combined with these stresses. Our previous investigations in younger individuals demonstrated that minimal resistance exercise and nutritional supplementation with essential amino acids (EAA) can maintain LBM and preserve or diminish the loss of muscle function. Therefore, the goal of this project is to examine the effects of EAA alone or in combination with resistance or walking exercise on muscle protein metabolism, LBM, and muscle function in older individuals. We propose to study three groups of older men and women (65-80 years) before, during, and after 10 days of bedrest: 1) a group who will receive three supplements per day of EAA alone (EAA), 2) a group that will receive the same EAA supplementation plus three sessions of resistance exercise throughout bedrest (EAA+RE), and 3) a group who will receive EAA supplementation plus the standard-of-care daily walking exercise (EAA+WE). The effects of RE and WE alone will be tested by Dr. Trappe at UAMS; however, we will examine the hypotheses that the combination of EAA and these exercise regimens will be more effective in preserving muscle protein synthesis, LBM, and muscle function than either intervention alone. Further, we propose that combination of these interventions will expedite recovery from bedrest. Finally, we propose that these interventions, or combination of interventions, will be effective in maintaining muscle protein synthesis, muscle mass, and function in the elderly.
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