Inactivity from one overnight hospital stay reduces basal muscle protein synthesis in young adults (820.15)

Abstract

Multiple day (3‐14d) models of bed‐rest or step reduction have shown that physical inactivity decreases muscle protein synthesis (MPS). Little is known regarding how soon this decrement in muscle protein synthesis occurs following inactivity, such as during an overnight hospital stay, which has been associated with reductions in physical activity. To examine the effect of inactivity from one overnight stay, on MPS we recruited 75 young subjects that were assigned to either walk on to the clinical research unit at 7am before assessment of MPS (Walk‐on) or as inpatient subjects who were studied after an overnight stay (Overnight) and before assessment of MPS the following morning. We had a subset of subjects (from Walk‐on and Overnight) wear a step activity monitor, which collected step data from midnight until initiation of the tracer infusion. We used stable isotopic methods and collected vastus lateralis biopsies 2‐3h apart for assessment of mixed MPS. Walk‐on and Overnight took ~1210 and ~88 steps, respectively. MPS was ~20% lower (p<0.05) for Overnight as compared to Walk‐on. We conclude that one overnight stay in the hospital is an inactivity model.Grant Funding Source: NIH/NIAMS (AR049877) and NIH/NIA P30 AG024832