title: Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women.
abstract: OBJECTIVE
  To investigate the effects of low-volume high-intensity interval training (HIT) performed in the fasted (FAST) versus fed (FED) state on body composition, muscle oxidative capacity, and glycemic control in overweight/obese women.
  
  
  METHODS
  Sixteen women (27 ± 8 years, BMI: 29 ± 6 kg/m(2) , VO2peak : 28 ± 3 ml/kg/min) were assigned to either FAST or FED (n = 8 each) and performed 18 sessions of HIT (10× 60-s cycling efforts at ∼90% maximal heart rate, 60-s recovery) over 6 weeks.
  
  
  RESULTS
  There was no significant difference between FAST and FED for any measured variable. Body mass was unchanged following training; however, dual energy X-ray absorptiometry revealed lower percent fat in abdominal and leg regions as well as the whole body level (main effects for time, P ≤ 0.05). Fat-free mass increased in leg and gynoid regions (P ≤ 0.05). Resting muscle biopsies revealed a training-induced increase in mitochondrial capacity as evidenced by increased maximal activities of citrate synthase and β-hydroxyacyl-CoA dehydrogenase (P ≤ 0.05). There was no change in insulin sensitivity, although change in insulin area under the curve was correlated with change in abdominal percent fat (r = 0.54, P ≤ 0.05).
  
  
  CONCLUSIONS
  Short-term low-volume HIT is a time-efficient strategy to improve body composition and muscle oxidative capacity in overweight/obese women, but fed- versus fasted-state training does not alter this response.
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jenna B
authors.initials: JB
authors.lastname: Gillen
authors.forename: Michael E
authors.initials: ME
authors.lastname: Percival
authors.forename: Alison
authors.initials: A
authors.lastname: Ludzki
authors.forename: Mark A
authors.initials: MA
authors.lastname: Tarnopolsky
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Gibala
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology; D000328:Adult; D001823:Body Composition; D004038:Diet, Reducing; D004435:Eating / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005215:Fasting / Q000378:metabolism*; D005260:Female; D006801:Humans; D018482:Muscle, Skeletal / Q000378:metabolism*; D050177:Overweight / Q000378:metabolism* / Q000628:therapy*; D010084:Oxidation-Reduction; D061217:Weight Reduction Programs; D055815:Young Adult