{"id":{"repo_id":"utmb","oai_identifier":"oai:utmb-ir.tdl.org:2152.3/666"},"canonical_url":"https://search.dev.ndltd.org/etd/utmb/oai:utmb-ir.tdl.org:2152.3/666","repository":{"repo_id":"utmb","name":"University of Texas Medical Branch","base_url":"https://utmb-ir.tdl.org/server/oai/request"},"display":{"title":"Effects of Leucine on Skeletal Muscle During 14 d Bed Rest in Middle-aged Adults","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.","abstract_html":"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.","abstract_has_math":false,"creators":["English, Kirk L"],"institution":"The University of Texas Medical Branch at Galveston","degree_name":"Rehabilitation Science","degree_level":"Doctoral","degree_discipline":"Nutrition and Metabolism","degree_department":null,"school":null,"contributors":[],"advisors":["Paddon-Jones, Douglas J"],"committee_chairs":[],"committee_members":["Adams, Gregory R.","Ploutz-Snyder, Robert","Sheffield-Moore, Melinda","Sidossis, Labros S."],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T05:50:48Z","subjects":["Bed rest","atrophy","muscle metabolism","protein synthesis","muscle mass","muscle strength","insulin sensitivity","leucine","essential amino acid","nutrition","aging","middle-aged","stable isotope tracer","FSR","mTOR","spaceflight"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2152.3/666","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Paddon-Jones, Douglas J"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Adams, Gregory R.","Ploutz-Snyder, Robert","Sheffield-Moore, Melinda","Sidossis, Labros S."]},{"key":"dc:creator","label":"Author","values":["English, Kirk L"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2016-05-05T21:33:18Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2016-05-05T21:33:18Z"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nutrition and Metabolism"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Rehabilitation Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["The University of Texas Medical Branch at Galveston"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Bed rest","atrophy","muscle metabolism","protein synthesis","muscle mass","muscle strength","insulin sensitivity","leucine","essential amino acid","nutrition","aging","middle-aged","stable isotope tracer","FSR","mTOR","spaceflight"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/2152.3/666"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Effects of Leucine on Skeletal Muscle During 14 d Bed Rest in Middle-aged Adults"]}]}],"canonical_facts":{"dc:contributor.advisor":["Paddon-Jones, Douglas J"],"dc:contributor.committeemember":["Adams, Gregory R.","Ploutz-Snyder, Robert","Sheffield-Moore, Melinda","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: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","atrophy","muscle metabolism","protein synthesis","muscle mass","muscle strength","insulin sensitivity","leucine","essential amino acid","nutrition","aging","middle-aged","stable isotope tracer","FSR","mTOR","spaceflight"],"dc:title":["Effects of Leucine on Skeletal Muscle During 14 d Bed Rest in Middle-aged Adults"],"dc:type":["Thesis"],"thesis:degree_discipline":["Nutrition and Metabolism"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["Rehabilitation Science"],"thesis:institution_name":["The University of Texas Medical Branch at Galveston"]},"updated_at":"2026-07-24T05:50:48Z"}