title: Circuit weight training and cardiac morphology: a trial with magnetic resonance imaging.
abstract: BACKGROUND
  Aerobic training (AT) and circuit weight training (CWT) improve peak oxygen uptake (VO(2)peak). During CWT the circulatory system is exposed to higher pressure, which could induce left ventricle morphological adaptations, possibly distinct from those derived from aerobic training.
  
  
  OBJECTIVE
  To compare the effects of aerobic training and CWT upon morphological and functional cardiac adaptations detected by magnetic resonance imaging.
  
  
  METHODS
  Twenty healthy sedentary individuals were randomly assigned to participate in a 12-week programme of aerobic training (n = 6), CWR (n = 7) or no intervention (n = 7, controls). Training programmes consisted of 36 sessions, 35 min each, 3 times per week, at 70% of maximal heart rate, and CWT included series of resistance exercises performed at 60% of 1 maximal repetition. Cardiopulmonary exercise testing and cardiac magnetic resonance imaging were performed before and after the intervention.
  
  
  RESULTS
  There was a similar improvement in VO(2)peak following aerobic training (mean (SD) increment: 12 (4)%) and CWT (12 (4)%), while there was no change in the control group. Aerobic training (12 (6)%) and CWT (16 (5)%) improved strength in the lower limbs, and only CWT resulted in improvement of 13 (4)% in the strength of the upper limbs. However, there were no detectable changes in left ventricular mass, end-diastolic volume, stroke volume or ejection fraction.
  
  
  CONCLUSIONS
  In previously sedentary individuals, short-term CWT and aerobic training induce similar improvement in functional capacity without any adaptation in cardiac morphology detectable by cardiac magnetic resonance imaging.
authors.affiliation: Institute of Cardiology of Rio Grande do Sul/FUC (IC/FUC), Porto Alegre, Brazil.
authors.forename: M D
authors.initials: MD
authors.lastname: Camargo
authors.forename: R
authors.initials: R
authors.lastname: Stein
authors.forename: J P
authors.initials: JP
authors.lastname: Ribeiro
authors.forename: P R
authors.initials: PR
authors.lastname: Schvartzman
authors.forename: M O
authors.initials: MO
authors.lastname: Rizzatti
authors.forename: B D
authors.initials: BD
authors.lastname: Schaan
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D016277:Ventricular Function, Left / Q000502:physiology*; D014891:Weight Lifting / Q000502:physiology*