Circuit weight training and cardiac morphology: A trial with Magnetic Resonance Imaging

Marcelo D Camargo ¹, Ricardo Stein ², Jorge P Ribeiro ², Paulo R Schvartzman ³, Marcele O Rizzatti ² and Beatriz D Schaan ^1*

¹ Institute of Cardiology of Rio Grande do Sul / FUC, Brazil
² Exercise Pathophysiology Research Laboratory and Cardiology Division, Hospital de Clinicas de Porto, Brazil
³ Medicina Diagnoacute;stica Matilde;e de Deus Center, Brazil

^* To whom correspondence should be addressed. E-mail: beatrizschaan{at}gmail.com.

Accepted 29 May 2007

Abstract

Background: Aerobic training (AT) and circuit weight training (CWT) improve peak oxygen uptake (VO2 peak). During CWT the circulatory system is exposed to higher pressure, which could induce left ventricle morphological adaptations, possibly distinct from those derived from AT.

Objective: To compare the effects of AT 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 program of aerobic training (n = 6), CWR (n =7), or to no intervention (n = 7, controls). Training programs 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: Aerobic training (mean ± SD increment: 12 ± 4 %) and CWT (12 ± 4 %) improved similarly VO2 peak, 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.

Conclusion: In previously sedentary individuals, short-term CWT and AT induce similar improvement in functional capacity without any adaptation in cardiac morphology detectable by cardiac magnetic resonance imaging.

Key Words: cardiac hypertrophy, endurance training, resistive training

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