title: Comparison of leucine kinetics in endurance-trained and sedentary humans.
abstract: Whole body leucine kinetics was compared in endurance-trained athletes and sedentary controls matched for age, gender, and body weight. Kinetic studies were performed during 3 h of rest, 1 h of exercise (50% maximal oxygen consumption), and 2 h of recovery. When leucine kinetics were expressed both per unit of body weight and per unit of fat-free mass, both groups demonstrated an increase in leucine oxidation during exercise (P < 0.01). Trained athletes had a greater leucine rate of appearance during exercise and recovery compared with their sedentary counterparts (P < 0.05) and an increased leucine oxidation at all times on the basis of body weight (P < 0.05). However, all of these between-group differences were eliminated when leucine kinetics were corrected for fat-free tissue mass. Therefore, correction of leucine kinetics for fat-free mass may be important when cross-sectional investigations on humans are performed. Furthermore, leucine oxidation, when expressed relative to whole-body oxygen consumption during exercise, was similar between groups. It is concluded that there was no difference between endurance-trained and sedentary humans in whole body leucine kinetics during rest, exercise, or recovery when expressed per unit of fat-free tissue mass.
authors.affiliation: Exercise Science Program, University of Rhode Island, Kingston, Rhode Island 02881, USA.LAMONT@URIACC.URI.EDU
authors.forename: L S
authors.initials: LS
authors.lastname: Lamont
authors.forename: A J
authors.initials: AJ
authors.lastname: McCullough
authors.forename: S C
authors.initials: SC
authors.lastname: Kalhan
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D001835:Body Weight / Q000502:physiology; D005260:Female; D006801:Humans; D007651:Keto Acids / Q000097:blood; D007930:Leucine / Q000493:pharmacokinetics*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D011659:Pulmonary Gas Exchange
chemical_list: D001786:Blood Glucose; D007651:Keto Acids; C013082:alpha-ketoisocaproic acid; D007930:Leucine