title: High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys.
abstract: OBJECTIVE
  High-intensity interval exercise (HIIE) may offer a time efficient means to improve health outcomes compared to moderate-intensity exercise (MIE). This study examined the acute effect of HIIE compared to a work-matched bout of MIE on glucose tolerance, insulin sensitivity (IS), resting fat oxidation and exercise enjoyment in adolescent boys.
  
  
  METHODS
  Within-measures design with counterbalanced experimental conditions.
  
  
  METHODS
  Nine boys (14.2 ± 0.4 years) completed three conditions on separate days in a counterbalanced order: (1) HIIE; (2) work matched MIE, both on a cycle ergometer; and (3) rest (CON). An oral glucose tolerance test (OGTT) was performed after exercise or rest and the area under curve (AUC) responses for plasma [glucose] and [insulin] were calculated, and IS estimated (Cederholm index). Energy expenditure and fat oxidation were measured following the OGTT using indirect calorimetry. Exercise enjoyment was assessed using the Physical Activity Enjoyment Scale.
  
  
  RESULTS
  The incremental AUC (iAUC) for plasma [glucose] was reduced following both MIE (-23.9%, P = 0.013, effect size [ES] = -0.64) and HIIE (-28.9%, P=0.008, ES = -0.84) compared to CON. The iAUC for plasma [insulin] was lower for HIIE (-24.2%, P = 0.021, ES = -0.71) and MIE (-29.1%, P = 0.012, ES = -0.79) compared to CON. IS increased by 11.2% after HIIE (P = 0.03, ES = 0.76) and 8.4% after MIE (P = 0.10, ES = 0.58). There was a trend for an increase in fat oxidation following HIIE (P = 0.097, ES = 0.70). Both HIIE and MIE were rated as equally enjoyable (P > 0.05, ES < 0.01).
  
  
  CONCLUSIONS
  A single bout of time efficient HIIE is an effective alternative to MIE for improving glucose tolerance and IS in adolescent boys immediately after exercise.
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Cockcroft
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Williams
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Owen W
authors.initials: OW
authors.lastname: Tomlinson
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Vlachopoulos
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Jackman
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Armstrong
authors.affiliation: Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK. Electronic address: A.R.Barker@exeter.ac.uk.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Barker
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000293:Adolescent; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology* / Q000523:psychology; D005951:Glucose Tolerance Test; D006240:Happiness; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*
chemical_list: D001786:Blood Glucose
keywords: Cardiometabolic health; Fat oxidation; Physical activity; Youth