title: Short-term high-intensity interval and continuous moderate-intensity training improve maximal aerobic power and diastolic filling during exercise.
abstract: OBJECTIVE
  This study examined the effects of short-term high-intensity interval training (HIT) and continuous moderate-intensity training (CMT) on cardiac function in young, healthy men.
  
  
  METHODS
  Sixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six sessions over a 12-day training period. HIT consisted of 8-12 intervals of cycling for 60 s at 95-100% of pre-training maximal aerobic power (VO(2max)), interspersed by 75 s of cycling at 10% VO(2max). CMT involved 90-120 min of cycling at 65% pre-training VO(2max). Left ventricular (LV) function was determined at rest and during submaximal exercise (heart rate ~105 bpm) using two-dimensional and Doppler echocardiography.
  
  
  RESULTS
  Training resulted in increased calculated plasma volume (PV) in both groups, accompanied by improved VO(2max) in HIT (HIT: from 39.5 ± 7.1 to 43.9 ± 5.5 mL kg(-1) min(-1); CMT: from 39.9 ± 5.9 to 41.7 ± 5.3 mL kg(-1) min(-1); P < 0.001). Resting LV function was not altered. However, increased exercise stroke volume (P = 0.02) and cardiac output (P = 0.02) were observed, secondary to increases in end-diastolic volume (P < 0.001). Numerous Doppler and speckle tracking indices of diastolic function were similarly enhanced during exercise in both training groups and were related to changes in PV.
  
  
  CONCLUSIONS
  Short-term HIT and CMT elicit rapid improvements in VO2max and LV filling without global changes in cardiac performance at rest.
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON, M5S 2W6, Canada.
authors.forename: Sam
authors.initials: S
authors.lastname: Esfandiari
authors.forename: Zion
authors.initials: Z
authors.lastname: Sasson
authors.forename: Jack M
authors.initials: JM
authors.lastname: Goodman
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003971:Diastole; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D055070:Resistance Training; D013318:Stroke Volume; D014463:Ultrasonography; D016277:Ventricular Function, Left