Effects of Leucine on Skeletal Muscle During 14 d Bed Rest in Middle-aged Adults
dc.contributor.advisor | Paddon-Jones, Douglas J | |
dc.contributor.committeeMember | Adams, Gregory R. | |
dc.contributor.committeeMember | Ploutz-Snyder, Robert | |
dc.contributor.committeeMember | Sheffield-Moore, Melinda | |
dc.contributor.committeeMember | Sidossis, Labros S. | |
dc.creator | English, Kirk L | |
dc.date.accessioned | 2016-05-05T21:33:18Z | |
dc.date.available | 2016-05-05T21:33:18Z | |
dc.date.created | 2013-08 | |
dc.date.submitted | August 2013 | |
dc.date.updated | 2016-05-05T21:33:18Z | |
dc.description.abstract | Aging is associated with a slow, progressive loss of muscle mass and strength. Mechanical unloading, such as that commonly experienced during hospitalization or spaceflight, results in a rapid loss of muscle mass and strength, particularly in older adults. Exercise, a potent countermeasure to such losses, is often impractical in acutely ill patients. The essential amino acid leucine has been shown to acutely stimulate muscle protein synthesis (MPS), a decrease in which mechanistically drives inactivity-induced losses in muscle. This study evaluated the effects of leucine supplementation (0.06 g • kg • meal-1; LEU) with each of three daily meals in middle-aged adults, a largely unstudied age group, during 14 d bed rest (BR) and subsequent 7 d rehabilitation. Primary findings were: 1) leucine attenuated the loss of whole body lean mass during the first 7 d of BR compared to control subjects (LEU: -0.6±0.2 kg vs. CON: -1.1±0.2 kg, p<0.05) and reduced or prevented decrements in knee extensor strength (LEU: -8±3% vs. CON: -15±3%, p<0.05), ankle extensor strength (LEU: -13±5% vs. CON: -20±5%, p<0.05), and knee extensor endurance (LEU: -2±4% vs. CON: -14±3%, p<0.05) during 14 d BR; 2) LEU maintained both post-absorptive and post-prandial MPS during BR; in contrast, BR decreased post-absorptive MPS (pre-BR: 0.061% • h-1 vs. post-BR: 0.043% • h-1, p<0.05); 3) insulin area under the curve during an oral glucose tolerance test was unchanged in LEU after BR (21±8%) but elevated in CON (52±23%, p<0.05) and whole body insulin sensitivity in LEU was significantly increased above pre-BR values after 7 d rehabilitation (17±10% vs. CON: -9±9%, p<0.05). Leucine is an inexpensive, low volume supplement that can be easily incorporated into the daily meals of middle-aged adults to maintain muscle protein synthesis and protect muscle mass, strength, and insulin sensitivity during periods of physical inactivity characteristic of hospitalized acute illness and spaceflight. | |
dc.format.mimetype | application/pdf | |
dc.identifier.uri | http://hdl.handle.net/2152.3/666 | |
dc.subject | Bed rest | |
dc.subject | atrophy | |
dc.subject | muscle metabolism | |
dc.subject | protein synthesis | |
dc.subject | muscle mass | |
dc.subject | muscle strength | |
dc.subject | insulin sensitivity | |
dc.subject | leucine | |
dc.subject | essential amino acid | |
dc.subject | nutrition | |
dc.subject | aging | |
dc.subject | middle-aged | |
dc.subject | stable isotope tracer | |
dc.subject | FSR | |
dc.subject | mTOR | |
dc.subject | spaceflight | |
dc.title | Effects of Leucine on Skeletal Muscle During 14 d Bed Rest in Middle-aged Adults | |
dc.type | Thesis | |
dc.type.material | text | |
thesis.degree.department | Rehabilitation Science | |
thesis.degree.discipline | Nutrition and Metabolism | |
thesis.degree.grantor | The University of Texas Medical Branch at Galveston | |
thesis.degree.level | Doctoral | |
thesis.degree.name | Rehabilitation Science |