title: The effects of interval- vs. continuous exercise on excess post-exercise oxygen consumption and substrate oxidation rates in subjects with type 2 diabetes.
abstract: BACKGROUND
  For unknown reasons, interval training often reduces body weight more than energy-expenditure matched continuous training. We compared the acute effects of time-duration and oxygen-consumption matched interval- vs. continuous exercise on excess post-exercise oxygen consumption (EPOC), substrate oxidation rates and lipid metabolism in the hours following exercise in subjects with type 2 diabetes (T2D).
  
  
  METHODS
  Following an overnight fast, ten T2D subjects (M/F: 7/3; age=60.3±2.3years; body mass index (BMI)=28.3±1.1kg/m(2)) completed three 60-min interventions in a counterbalanced, randomized order: 1) control (CON), 2) continuous walking (CW), 3) interval-walking (IW - repeated cycles of 3min of fast and 3min of slow walking). Indirect calorimetry was applied during each intervention and repeatedly for 30min per hour during the following 5h. A liquid mixed meal tolerance test (MMTT, 450kcal) was consumed by the subjects 45min after completion of the intervention with blood samples taken regularly.
  
  
  RESULTS
  Exercise interventions were successfully matched for total oxygen consumption (CW=1641±133mL/min; IW=1634±126mL/min, P>0.05). EPOC was higher after IW (8.4±1.3l) compared to CW (3.7±1.4l, P<0.05). Lipid oxidation rates were increased during the MMTT in IW (1.03±0.12mg/kg per min) and CW (0.87±0.04mg/kg per min) compared with CON (0.73±0.04mg/kg per min, P<0.01 and P<0.05, respectively), with no difference between IW and CW. Moreover, free fatty acids and glycerol concentrations, and glycerol kinetics were increased comparably during and after IW and CW compared to CON.
  
  
  CONCLUSIONS
  Interval exercise results in greater EPOC than oxygen-consumption matched continuous exercise during a post-exercise MMTT in subjects with T2D, whereas effects on substrate oxidation and lipid metabolism are comparable.
authors: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. Electronic address: k_karstoft@dadlnet.dk.
authors: Kristian
authors: K
authors: Karstoft
authors: School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.
authors: Gareth A
authors: GA
authors: Wallis
authors: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors: Bente K
authors: BK
authors: Pedersen
authors: The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark; School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, UK; Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.
authors: Thomas P J
authors: TP
authors: Solomon
mesh_terms: D015992:Body Mass Index; D002153:Calorimetry, Indirect; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004435:Eating; D004734:Energy Metabolism; D015444:Exercise; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005990:Glycerol / Q000097:blood; D006801:Humans; D007700:Kinetics; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D016138:Walking
chemical_list: D005230:Fatty Acids, Nonesterified; D005990:Glycerol
keywords: EPOC; Interval walking; Lipid metabolism; Lipolysis; Walking