title: The association among skeletal muscle phosphocreatine recovery, adiposity, and insulin resistance in children.
abstract: Obesity is associated with cardiometabolic disturbances, which may have significant implications for musculoskeletal health and exercise tolerance.
  
  
  
  We sought to determine the association between muscle structure, function, and metabolism in adolescents across the weight spectrum.
  
  
  
  This cross-sectional case-control study included overweight and obese participants (n = 24) 8-18 years of age with a body mass index (BMI) ≥ 85th percentile for age and gender, and non-obese participants (n = 24) with a BMI < 85thpercentile. Body composition, physical activity, peak aerobic capacity, cardiometabolic blood markers and insulin resistance (measured by the homeostatic model assessment of insulin resistance, HOMA-IR), skeletal muscle mitochondrial oxidative capacity (via31Phosphorous-Magnetic Resonance Spectroscopy,31P-MRS, to assess phosphocreatine (PCr) recovery after exercise), and extramyocellular and intramyocellular lipid (IMCL) levels (via1Hydrogen-MRS) were assessed. Stepwise regression was performed to examine the factors associated with oxidative capacity.
  
  
  
  bese and overweight patients had similar age, height, and physical activity to non-obese controls, but obese and overweight participants exhibited higher insulin resistance. Obese and overweight participants had longer PCr recovery than non-obese controls following 5x30s of moderate-intensity exercise (51.2 ± 20.1 s vs. 23.9 ± 7.5 s, p = 0.004). In univariate correlation analysis, impaired PCr recovery was associated with a higher BMI z-score (rs= 0.51, p < 0.001), circulating triglycerides (rs= 0.41, p = 0.005), and HOMA-IR (rs= 0.46, p = 0.001). In stepwise multivariate regression analysis, impaired PCr recovery was associated with a higher BMI z-score (β = 0.47, p = 0.002), but not insulin resistance (β = 0.07, p = 0.07) or circulating triglycerides (β = 0.16 p = 0.33).
  
  
  
  A slower phosphocreatine recovery following aerobic exercise is strongly associated with increasing adiposity. A slower metabolic recovery following aerobic exercise stress suggests that endurance exercise training in obese adolescents may be an optimal strategy to target exercise intolerance in this cohort.
authors.affiliation: Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8.|Faculty of Kinesiology and Physical Education, 100 Devonshire Place, Toronto, Ontario, M5S 2C9.
authors.forename: Greg D
authors.initials: GD
authors.lastname: Wells
authors.affiliation: Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8.|Faculty of Kinesiology and Physical Education, 100 Devonshire Place, Toronto, Ontario, M5S 2C9.
authors.forename: Laura
authors.initials: L
authors.lastname: Banks
authors.affiliation: Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8.|Faculty of Kinesiology and Physical Education, 100 Devonshire Place, Toronto, Ontario, M5S 2C9.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Caterini
authors.affiliation: Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8.|Faculty of Kinesiology and Physical Education, 100 Devonshire Place, Toronto, Ontario, M5S 2C9.
authors.forename: Sara
authors.initials: S
authors.lastname: Thompson
authors.affiliation: School of Biomedical Engineering, McMaster University, 1280 Main St. West, Hamilton.|Department of Electrical and Computer Engineering, McMaster University, 1280 Main St. West, Hamilton.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Noseworthy
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8.
authors.forename: Tammy
authors.initials: T
authors.lastname: Rayner
authors.affiliation: Division of Endocrinology, Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8.
authors.forename: Catriona
authors.initials: C
authors.lastname: Syme
authors.affiliation: Division of Cardiology, Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8.|Department of Pediatrics, University of Toronto, Toronto, M5S 1A8.
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.affiliation: Physiology and Experimental Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8.|Division of Endocrinology, Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8.|Department of Pediatrics, University of Toronto, Toronto, M5S 1A8.
authors.forename: Jill
authors.initials: J
authors.lastname: Hamilton
mesh_terms: D050154:Adiposity / Q000502:physiology*; D000293:Adolescent; D001823:Body Composition / Q000502:physiology; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D050177:Overweight / Q000378:metabolism*; D063766:Pediatric Obesity / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D014280:Triglycerides; D010725:Phosphocreatine
keywords: 31P-magnetic resonance spectroscopy; childhood obesity; exercise; insulin resistance; phosphocreatine recovery