Key points• Healthy sedentary ageing leads to stiffening of the heart; however, when this process occurs during ageing has been unknown.• In this study, 70 healthy sedentary subjects were stratified into four groups: 'young' -G 21−34 :21-34 years; 'early middle-age' -G 35−49 : 35-49 years; 'late middle-age' -G 50−64 : 50-64 years; and 'seniors' -G ≥65 : ≥65 years.• Invasive catheter measurements showed a substantially greater left ventricular (LV) compliance (more flexible/less stiff) in G 21−34 than G 50−64 and G ≥65 .• Although LV chamber compliance in G 50−64 and G ≥65 appeared identical, pressure-volume curves were shifted leftward, exhibiting a smaller volume for any given pressure with increasing age.• Our results suggest that LV stiffening with ageing occurs during the transition between youth and middle-age and becomes manifest between the ages of 50-64; LV volume contraction and remodelling follow in the senior years. Early-late middle age thus may represent a 'sweet spot' when interventions to prevent stiff ageing hearts may be most effective.Abstract Healthy, but sedentary ageing leads to marked atrophy and stiffening of the heart, with substantially reduced cardiac compliance; but the time course of when this process occurs during normal ageing is unknown. Seventy healthy sedentary subjects (39 female; 21-77 years) were recruited from the Dallas Heart Study, a population-based, random community sample and enriched by a second random sample from employees of Texas Health Resources. Subjects were highly screened for co-morbidities and stratified into four groups according to age: G 21−34 : 21-34 years, G 35−49 : 35-49 years, G 50−64 : 50-64 years, G ≥65 : ≥65 years. All subjects underwent invasive haemodynamic measurements with right heart catheterization to define Starling and left ventricular (LV) pressure-volume curves. LV end-diastolic volumes (EDV) were measured by echocardiography at baseline, −15 and −30 mmHg lower-body negative pressure, and 15 and 30 ml kg −1 saline infusion with simultaneous measurements of pulmonary capillary wedge pressure. There were no differences in heart rate or blood pressures among the four groups at baseline. Baseline EDV index was smaller in G ≥65 than other groups. LV diastolic pressure-volume curves confirmed a substantially greater LV compliance in G 21−34 compared with G 50−64 and G ≥65 , resulting in greater LV volume changes with preload manipulations. Although LV chamber compliance in G 50−64 and G ≥65 appeared identical, pressure-volume curves were shifted leftward, toward a decreased distensibility, with increasing age. These results suggest that LV stiffening in healthy ageing occurs during the transition between youth and middle-age and becomes manifest between the ages of 50 to 64. Thereafter, this LV stiffening is followed by LV volume contraction and remodelling after the age of 65.

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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.