Lifelong Physical Activity Regardless of Dose Is Not Associated With Myocardial Fibrosis

Abstract

Background Recent reports have suggested that long term intensive physical training may be associated with adverse cardiovascular effects, including the development of myocardial fibrosis. However, the dose-response association of different levels of lifelong physical activity on myocardial fibrosis has not been evaluated. Methods and Results Seniors free of major chronic illnesses were recruited from predefined populations based on the consistent documentation of stable physical activity over >25 years and were classified into 4 groups by the number of sessions/week of aerobic activities ≥ 30 minutes: Sedentary (Group 1) , < 2 sessions; Casual (Group 2), 2-3 sessions; Committed (Group 3), 4-5 sessions; and Masters athletes (Group 4), 6-7 sessions plus regular competitions. All subjects underwent cardiopulmonary exercise testing and cardiac magnetic resonance imaging (cMRI), including late gadolinium enhancement (LGE) assessment of fibrosis. Ninety-two subjects (mean age 69 years, 27% women) were enrolled. No significant differences in age or sex were seen between groups. Median peak oxygen uptake was 25 ml/kg/min, 26 ml/kg/min, 32 ml/kg/min, and 40 ml/kg/min for Groups 1, 2, 3, and 4, respectively. Cardiac MRI demonstrated increasing left ventricular end diastolic volumes, end systolic volumes, stroke volumes, and masses with increasing doses of lifelong physical activity. One subject in Group 2 had LGE, in a non-coronary distribution, and no subjects in groups 3 and 4 had evidence of LGE. Conclusions A lifelong history of consistent physical activity, regardless of “dose” ranging from sedentary to competitive marathon running, was not associated with the development of focal myocardial fibrosis.

The “Extreme Exercise Hypothesis”: Recent Findings and Cardiovascular Health Implications

“…The presence of myocardial fibrosis was strongly associated with the cumulative exercise dose. In contrast to studies from Germany [ 34 ] and the USA [ 35 ]. Bohm et al found no difference in left and right ventricular function parameters between 33 competitive elite male master endurance athletes and 33 controls matched for age, height, and weight, [ 34 ], and myocardial fibrosis was observed in only 1 athlete.…”

“…Bohm et al found no difference in left and right ventricular function parameters between 33 competitive elite male master endurance athletes and 33 controls matched for age, height, and weight, [ 34 ], and myocardial fibrosis was observed in only 1 athlete. Abdullah et al compared left ventricular characteristics across groups of long-term exercisers (< 2/2–3/4–5/6–7 exercise sessions/week) and found a stepwise improvement of cardiac structure and function with increasing doses of physical activity [ 35 ]. Among the 92 study participants, delayed gadolinium enhancement was observed in only 1 exerciser in the 2–3 sessions/week group.…”

An Update on the Role of Cardiorespiratory Fitness, Structured Exercise and Lifestyle Physical Activity in Preventing Cardiovascular Disease and Health Risk

“…reporting participation in lifelong exercise slow the age-related declines in CV function compared to sedentary or low active age matched counterparts. Much of our understanding of the preservative effects of regular ET comes from a series of reports that characterized the association between lifelong ET habits (sedentary, no more than one day of ET per week; casual, 2-3 days of ET per week; committed, 4-5 days of ET per week; and master's athletes, 6-7 days of ET per week)and CV function of older adults[48][49][50][51][52] . Through these investigations, it has become apparent that the long-term adaptations to ET may be organ specific.…”

Follistatin‐like 1: A dual regulator that promotes cardiomyocyte proliferation and fibrosis

“…The effect of exercise on the heart remains controversial. On the one hand, exercise promotes heart health and it is unrelated to myocardial fibrosis (Abdullah et al, 2016). On the other hand, long‐term excessive exercise can cause exercise‐induced arrhythmia and lead to exercise‐induced myocardial fibrosis (Rao, Wang, Bunner, Chang, & Shi, 2018; van de Schoor et al, 2016; Tahir et al, 2018).…”