title: Low-volume high-intensity interval training rapidly improves cardiopulmonary function in postmenopausal women.
abstract: OBJECTIVE
  This study compared the effects of a 2-week program of low-volume high-intensity interval training (HIT) with the effects of higher-volume moderate-intensity continuous training (CT) on cardiopulmonary and vascular functions in postmenopausal women.
  
  
  METHODS
  Twenty-two postmenopausal women were randomly assigned to undertake six HIT (n = 12) or CT (n = 10) sessions for 2 weeks. HIT sessions consisted of ten 1-minute intervals of cycling exercise at 100% of peak power output separated by 1 minute of active recovery. CT sessions involved 40 minutes of continuous cycling at 65% of peak power output. Variables assessed at baseline and 2 weeks included cardiopulmonary function (ventilatory threshold, peak oxygen uptake), macrovascular endothelial function (flow-mediated dilation of the brachial artery), and microvascular function (reactive hyperemia and local thermal hyperemia of forearm skin).
  
  
  RESULTS
  Eighteen participants completed the study (HIT, 11; CT, 7). Adherence to the exercise programs was excellent, with 107 of 108 sessions completed. Despite substantially lower total time commitment (∼2.5 vs. ∼5 h) and training volume (558 vs. 1,237 kJ) for HIT versus CT, increases from baseline in peak oxygen uptake achieved significance (P = 0.01) for the HIT group only (Δ = 2.2 mL kg min; P for interaction = 0.688). Improvements in exercise test duration were observed in both groups (HIT, 13%; CT, 5%; P for interaction = 0.194). There were no significant changes in macrovascular or microvascular function in either group.
  
  
  CONCLUSIONS
  The findings suggest that low-volume HIT is feasible and can lead to rapid improvements in cardiopulmonary function in postmenopausal women.
authors.affiliation: From the 1Center for Sport and Exercise Science, Sheffield Hallam University, Sheffield, UK; 2Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield, UK; and 3York Trials Unit, Department of Health Sciences, University of York, York, UK.
authors.forename: Markos
authors.initials: M
authors.lastname: Klonizakis
authors.forename: James
authors.initials: J
authors.lastname: Moss
authors.forename: Stephen
authors.initials: S
authors.lastname: Gilbert
authors.forename: David
authors.initials: D
authors.lastname: Broom
authors.forename: Jeff
authors.initials: J
authors.lastname: Foster
authors.forename: Garry A
authors.initials: GA
authors.lastname: Tew
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004730:Endothelium, Vascular / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008168:Lung / Q000502:physiology*; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D010101:Oxygen Consumption; D010807:Physical Endurance; D017698:Postmenopause / Q000502:physiology*