Two-Year Follow-Up on the Impact of Physical Fitness and Body Fatness on Children’s Heart Growth and Rising Blood Pressure: The Muscatine Study

To assess the relationship of changes in physical fitness and body composition to heart growth and rising blood pressure (BP) during early puberty, fat-free mass (FFM), body fatness (% fat), physical fitness (peak VO 2 , peak mechanical power, peak O 2 pulse, peak systolic blood pressure [SBP], and grip strength), Tanner stage, resting BP, and echocardiographic left ventricular mass (LVM) were measured in 123 children (age M = 10 years) and remeasured 2 years later. Increased FFM, increased grip strength, and increased peak power explained 28% of the variability in heart growth. Increased FFM, increased % fat, and decreased peak O 2 pulse explained 23% of the variability in rising SBP. During puberty, physical fitness is an independent predictor of changing heart size and systolic blood pressure. Results suggest that improvements in physical fitness and decreases in body fatness may have beneficial effects on children’s blood pressure.