A prospective randomised longitudinal MRI study of left ventricular adaptation to endurance and resistance exercise training in humans

Abstract

Non-technical summary This is the first study, to our knowledge, to use cardiac MRI before and after intensive and closely supervised resistance and endurance exercise training in humans. There is a long held belief that these different forms of training induce 'concentric' and 'eccentric' adaptation of the heart, but this concept is based on echocardiographic assessments and cross-sectional comparison of different types of elite athletes. Our findings, using highly sensitive MRI methodology, suggest that concept may need to be reconsidered. This study is of fundamental importance to the understanding of the impact of exercise on human cardiac morphology and physiology.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.

Blood Pressure and Left Ventricular Hypertrophy During American-Style Football Participation

“…This may explain the results of a recent longitudinal study in which individuals who maintained normal BP failed to develop LV hypertrophy during a 6-month period of strength training. 27 Our findings suggest that the concentric LV hypertrophy among strength athletes, traditionally presumed to be a benign adaptation, is actually a mild, previously unrecognized form of hypertensive LV remodeling that may carry adverse attendant prognostic implications. We therefore suggest that the term athlete's heart, typically used to imply a beneficial adaptive process, is not applicable to the concentric LV hypertrophy that develops among ASF linemen.…”

Cardiovascular adaptation in athletes

“…Several longitudinal studies of EICR have recently been completed and have established with certainty, a mechanistic link between exercise exposure and sport/physiology-specific EICR. 11,20,21 To date, the few longitudinal studies that have been completed and published have involved relatively short duration exercise exposure and have focused on relatively young athletes. Work from the Harvard Athlete Initiative has shown that 90 days of intense team-based training is sufficient to produce the sport-specific forms of left ventricular remodeling described above.…”

Regulation of Increased Blood Flow (Hyperemia) to Muscles During Exercise: A Hierarchy of Competing Physiological Needs

“…With endurance exercise training there can be an increase in left ventricular mass and chamber volume without wall thickening, a phenomenon known as eccentric cardiac hypertrophy (326,447,483). This adaptation augments stroke volume and thus maximum cardiac output (maximum heart rate does not change much) (10,144,274,414).…”