title: Effect of 1-h moderate-intensity aerobic exercise on intramyocellular lipids in obese men before and after a lifestyle intervention.
abstract: Intramyocellular lipids (IMCL) are depleted in response to an acute bout of exercise in lean endurance-trained individuals; however, it is unclear whether changes in IMCL content are also seen in response to acute and chronic exercise in obese individuals. We used magnetic resonance spectroscopy in 18 obese men and 5 normal-weight controls to assess IMCL content before and after an hour of cycling at the intensity corresponding with each participant's maximal whole-body rate of fat oxidation (Fatmax). Fatmax was determined via indirect calorimetry during a graded exercise test on a cycle ergometer. The same outcome measures were reassessed in the obese group after a 16-week lifestyle intervention comprising dietary calorie restriction and exercise training. At baseline, IMCL content decreased in response to 1 h of cycling at Fatmax in controls (2.8 ± 0.4 to 2.0 ± 0.3 A.U., -39%, p = 0.02), but not in obese (5.4 ± 2.1 vs. 5.2 ± 2.2 A.U., p = 0.42). The lifestyle intervention lead to weight loss (-10.0 ± 5.4 kg, p < 0.001), improvements in maximal aerobic power (+5.2 ± 3.4 mL/(kg·min)), maximal fat oxidation rate (+0.19 ± 0.22 g/min), and a 29% decrease in homeostasis model assessment score (all p < 0.05). However, when the 1 h of cycling at Fatmax was repeated after the lifestyle intervention, there remained no observable change in IMCL (4.6 ± 1.8 vs. 4.6 ± 1.9 A.U., p = 0.92). In summary, there was no IMCL depletion in response to 1 h of cycling at moderate intensity either before or after the lifestyle intervention in obese men. An effective lifestyle intervention including moderate-intensity exercise training did not impact rate of utilisation of IMCL during acute exercise in obese men.
authors.affiliation: a The University of Queensland Diamantina Institute, Brisbane, Australia.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ipavec-Levasseur
authors.affiliation: a The University of Queensland Diamantina Institute, Brisbane, Australia.|b School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia.|c Mater Research Institute, University of Queensland, Brisbane, Australia.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Croci
authors.affiliation: d Faculty of Physical Education and Sports, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Choquette
authors.affiliation: e Bond Institute of Health and Sport, Bond University, Robina, Australia.|f Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
authors.forename: Nuala M
authors.initials: NM
authors.lastname: Byrne
authors.affiliation: g Centre for Advanced Imaging, University of Queensland, Brisbane, Australia.
authors.forename: Gary
authors.initials: G
authors.lastname: Cowin
authors.affiliation: c Mater Research Institute, University of Queensland, Brisbane, Australia.|h Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Australia.
authors.forename: Trisha M
authors.initials: TM
authors.lastname: O'Moore-Sullivan
authors.affiliation: c Mater Research Institute, University of Queensland, Brisbane, Australia.
authors.forename: Johannes B
authors.initials: JB
authors.lastname: Prins
authors.affiliation: a The University of Queensland Diamantina Institute, Brisbane, Australia.|c Mater Research Institute, University of Queensland, Brisbane, Australia.
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: Hickman
mesh_terms: D000328:Adult; D031204:Caloric Restriction; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology; D009765:Obesity / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D040242:Risk Reduction Behavior; D057185:Sedentary Behavior; D013997:Time Factors; D016896:Treatment Outcome; D014280:Triglycerides / Q000378:metabolism*; D015431:Weight Loss
chemical_list: D014280:Triglycerides
keywords: diet; diète; ectopic fat; energy metabolism; entraînement physique; exercise training; graisse ectopique; intramyocellular triglycerides; magnetic resonance spectroscopy; maximal fat oxidation; muscle; métabolisme énergétique; obesity; obésité; oxydation maximale des graisses; spectroscopie par résonance magnétique; triglycérides intramyocellulaires