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Exercise effects on cardiac size and left ventricular diastolic function: relationships to changes in fitness, fatness, blood pressure and insulin resistance

The Division of Cardiology, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland USA

Correspondence to:
Correspondence to:
Professor Kerry J Stewart
Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, MD 21224, USA; kstewart{at}jhmi.edu

Objectives: To determine exercise training effects on cardiac size and left ventricular (LV) diastolic function and relationships of exercise induced changes in physiological and body composition parameters with cardiac parameters.

Design: Prospective, randomised controlled trial.

Subjects: Men and women (63.6 (5.7) years, body mass index 29.5 (4.4) kg/m²) with untreated hypertension (systolic blood pressure (BP) 130–159 or diastolic BP 85–99 mm Hg).

Main outcome measures: Cardiac size and LV diastolic function, peak oxygen uptake (VO₂), muscle strength, general and abdominal fatness, and insulin resistance.

Interventions: 6 months of exercise training versus usual care.

Results: When analysed by group at six months, cardiac size and LV diastolic function did not differ between exercisers (n = 51) and controls (n = 53), whereas exercisers had significantly higher peak VO₂ (28 v 24 ml/kg/min) and strength (383 v 329 kg), and lower fatness (34% v 37%), diastolic BP (73 v 75 mm Hg) and insulin resistance (quantitative insulin sensitivity check index 0.35 v 0.34) versus controls (all p 0.05). By regression analysis, among six month changes, increased peak VO₂ and reduced abdominal fat were associated with increased cardiac size. Increased peak VO₂ and reduced abdominal fat, BP and insulin resistance were associated with improved LV diastolic function. r Values ranged from 0.20 to 0.32 (p 0.05).

Conclusions: When examined by group assignment, exercise had no effect on cardiac size or LV diastolic function. When individual variations in six month changes were examined, participants attaining the greatest increases in fitness and reductions in abdominal fatness, insulin resistance and BP showed a modest trend towards physiological hypertrophy characterised by increased cardiac size and improved LV diastolic function. These results suggest that decreased abdominal fatness may have a role in improving cardiovascular health.

Abbreviations: A, peak late diastolic filling wave velocity; Am, peak mitral annular late diastolic velocity during atrial contraction; BP, blood pressure; DBP, diastolic blood pressure; E, peak early diastolic filling wave velocity; Em, peak mitral annular early diastolic velocity; LV, left ventricular; MRI, magnetic resonance imaging; QUICKI, quantitative insulin sensitivity check index; SBP, systolic blood pressure; VO₂, oxygen uptake

Keywords: exercise; blood pressure; obesity; diastole; cardiac structure