Muscle Regrowth During Physical Rehabilitation and Amino Acid Supplementation

The general hypothesis is that in older adults muscle regrowth after an acute musculoskeletal stress will be positively influenced by traditional physical rehabilitation, and further enhanced by nutritional supplementation. Using state-of-the-art stable isotope methodologies for the study of muscle metabolism and methodologies for the measurement of cell signaling, we will test the following specific hypotheses: 1) Total knee arthroplasty (TKA) induces an acute net protein catabolism mainly by reducing muscle protein synthesis; 2) TKA induced catabolism is attenuated by the ingestion of essential amino acids (EAA); 3) EAA supplementation in combination with physical therapy (PT) will stimulate muscle protein synthesis and mTOR signaling to a greater extent than PT with Placebo; and 4) EAA supplementation during TKA PT rehabilitation will improve muscle strength, muscle volume and functional outcomes to a greater extent than PT with Placebo. Public Benefit: This research will focus rehabilitation efforts on specific and currently unresolved mechanisms responsible for muscle loss following total knee replacement in older adults. While knee pain due to bone arthritis is often alleviated after knee replacement, complete return of physical function and independence is difficult to achieve. This research will help to restore physical function and independence in the rapidly growing population of older adults with knee arthritis.