One Week of Bed‐rest Substantially Reduces Muscle Mass and Induces Insulin Resistance in Healthy, Young Males

Abstract

Background The recovery from illness or injury is generally accompanied by short periods (<1 week) of bed-rest, which can contribute substantially to the development of sarcopenia. Whereas the functional and metabolic consequences of prolonged (> 1 month) bed-rest have been well-established, the impact of short-term bed-rest remains largely unexplored. The present study assessed the effects of one week of bed-rest on skeletal muscle mass, leg strength, and whole-body insulin sensitivity. Methods: Ten healthy males (23±1 y) were subjected to 7 days of strict bed-rest. Prior to and following bed-rest, a DEXA scan, CT scan of the upper leg, and a one-step hyperinsulinemic-euglycemic clamp were performed to assess lean body mass, quadriceps cross sectional area (CSA) and peripheral insulin sensitivity, respectively. Additionally, prior to and after bed-rest, an incremental cycle ergometer test and a 1-Repetition Maximum (1RM) test were performed to determine VO2peak and maximal leg strength. Results: One week of bed-rest resulted in 1.4±0.2 kg loss of lean tissue mass (P<0.01) and a 3.2±1.0% loss of quadriceps CSA (P<0.01). Glucose infusion rates decreased from 62±6 to 42±3 μmol·kg FFM-1·min-1, representing a 29±5% decline in peripheral insulin sensitivity (P<0.01). Following bed-rest, VO2peak and 1RM had declined by 6.4±2.3% (P<0.05) and 6.9±1.4% (P<0.01), respectively. Conclusion One week of bed-rest substantially reduces muscle mass, muscle strength, oxidative capacity, and peripheral insulin sensitivity. Effective strategies need to be designed to prevent the loss of muscle mass and decline in metabolic health during short periods of muscle disuse.