title: A prospective randomised longitudinal MRI study of left ventricular adaptation to endurance and resistance exercise training in humans.
abstract: The principle that 'concentric' cardiac hypertrophy occurs in response to strength training, whilst 'eccentric' hypertrophy results from endurance exercise has been a fundamental tenet of exercise science. This notion is largely based on cross-sectional comparisons of athletes using echocardiography. In this study, young (27.4 ± 1.1 years) untrained subjects were randomly assigned to supervised, intensive, endurance (END, n = 10) or resistance (RES, n = 13) exercise and cardiac MRI scans and myocardial speckle tracking echocardiography were performed at baseline, after 6 months of training and after a subsequent 6 weeks of detraining. Aerobic fitness increased significantly in END (3.5 to 3.8 l min(-1), P < 0.05) but was unchanged in RES. Muscular strength significantly improved compared to baseline in both RES and END ( = 53.0 ± 1.1 versus 36.4 ± 4.5 kg, both P < 0.001) as did lean body mass (2.3 ± 0.4 kg, P < 0.001 versus 1.4 ± 0.6 kg P < 0.05). MRI derived left ventricular (LV) mass increased significantly following END (112.5 ± 7.3 to 121.8 ± 6.6 g, P < 0.01) but not RES, whilst training increased end-diastolic volume (LVEDV, END: +9.0 ± 5.0 versus RES +3.1 ± 3.6 ml, P = 0.05). Interventricular wall thickness significantly increased with training in END (1.06 ± 0.0 to 1.14 ± 0.06, P < 0.05) but not RES. Longitudinal strain and strain rates did not change following exercise training. Detraining reduced aerobic fitness, LV mass and wall thickness in END (P < 0.05), whereas LVEDV remained elevated. This study is the first to use MRI to compare LV adaptation in response to intensive supervised endurance and resistance training. Our findings provide some support for the 'Morganroth hypothesis', as it pertains to LV remodelling in response to endurance training, but cast some doubt over the proposal that remodelling occurs in response to resistance training.
authors.affiliation: School of Sport Science, Exercise & Health (M408), The University of Western Australia, 35 Stirling Highway, Crawley Perth, Western Australia, 6009 Australia.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Spence
authors.forename: Louise H
authors.initials: LH
authors.lastname: Naylor
authors.forename: Howard H
authors.initials: HH
authors.lastname: Carter
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Buck
authors.forename: Lawrence
authors.initials: L
authors.lastname: Dembo
authors.forename: Conor P
authors.initials: CP
authors.lastname: Murray
authors.forename: Philip
authors.initials: P
authors.lastname: Watson
authors.forename: David
authors.initials: D
authors.lastname: Oxborough
authors.forename: Keith P
authors.initials: KP
authors.lastname: George
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Green
mesh_terms: D000328:Adult; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000209:etiology* / Q000503:physiopathology; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D053580:Muscle Strength; D010807:Physical Endurance / Q000502:physiology*; D055070:Resistance Training; D055815:Young Adult