Resistance Training and Cardiac Hypertrophy

Abstract

Resistance training (RT) is a popular method of conditioning to enhance sport performance as well as an effective form of exercise to attenuate the age-mediated decline in muscle strength and mass. Although the benefits of RT on skeletal muscle morphology and function are well established, its effect on left ventricular (LV) morphology remains equivocal. Some investigations have found that RT is associated with an obligatory increase in LV wall thickness and mass with minimal alteration in LV internal cavity dimension, an effect called concentric hypertrophy. However, others report that short- (<5 years) to long-term (>18 years) RT does not alter LV morphology, arguing that concentric hypertrophy is not an obligatory adaptation secondary to this form of exertion. This disparity between studies on whether RT consistently results in cardiac hypertrophy could be caused by: (i) acute cardiopulmonary mechanisms that minimise the increase in transmural pressure (i.e. ventricular pressure minus intrathoracic pressure) and LV wall stress during exercise; (ii) the underlying use of anabolic steroids by the athletes; or (iii) the specific type of RT performed. We propose that when LV geometry is altered after RT, the pattern is usually concentric hypertrophy in Olympic weightlifters. However, the pattern of eccentric hypertrophy (increased LV mass secondary to an increase in diastolic internal cavity dimension and wall thickness) is not uncommon in bodybuilders. Of particular interest, nearly 40% of all RT athletes have normal LV geometry, and these athletes are typically powerlifters. RT athletes who use anabolic steroids have been shown to have significantly higher LV mass compared with drug-free sport-matched athletes. This brief review will sort out some of the factors that may affect the acute and chronic outcome of RT on LV morphology. In addition, a conceptual framework is offered to help explain why cardiac hypertrophy is not always found in RT athletes.

Nandrolone and resistance training induce heart remodeling: Role of fetal genes and implications for cardiac pathophysiology

“…Exercise is known to be a potent cardiac hypertrophic stimulus, but the magnitude and pattern of left ventricular hypertrophy is dependent on the nature, duration, and intensity of exercise (Pluim et al, 2000;Haykowsky et al, 2002). In the heart, there are different morphological adaptations to resistance and aerobic training.…”

Endurance rather than sprint running training increases left ventricular wall thickness in female athletes

“…The results of the early echocardiographic examinations made researchers postulate that the type of LV hypertrophy is dependent on the training regimen applied, with clear differences between athletes, devoted to extensive training intended to increase aerobic capacity, and sprint/power athletes who train mainly (to increase) muscle strength/power instead of aerobic (cardiovascular) capacity. It was suggested that intense (anaerobic, strength/power, or sprint) exercise training results in more concentric LV hypertrophy, which is characterized by an increase in LV mass with augmented ratio of wall thickness to the LV diameter as well (Haykowsky et al 2002); whereas, voluminous isotonic (aerobic or endurance) exercise training results in more prominent enlargement of LV diameter (Morganroth et al 1975;Snoeckx et al 1982;Fagard 2003). This variation in cardiac structure could be attributed to different haemodynamic loading conditions (such as stroke volume, heart rate, and arterial blood pressure) during sprint versus endurance training.…”

“…The majority of the studies were performed on male athletes (Fagard 2003;Haykowsky et al 2002). Female athletes are believed to possess less pronounced cardiac size changes due to exercise training, which may be related to less arduous training and/or their hormonal environment (George et al 1999).…”

Loaded wheel running and muscle adaptation in the mouse

“…In addition, very little is known about the signaling pathways that mediate cardiac and skeletal muscle adaptation to resistance training. For example, some studies showed that resistance training increases left ventricular (LV) cavity dimensions, septal and posterior wall thickness, and cardiac mass (12,19); other studies in short-and long-term resistance-trained athletes demonstrated no changes in LV morphology or mass (19,20). The inconsistency of these data probably reflects the fact that the cardiac response to resistance exercise is likely to depend on the duration (long term vs. acute) and type (bodybuilding, power lifting, or high intensity) of training regimen.…”