Background: Global physical inactivity pandemic is responsible for more than 5 million deaths annually through its effects on non-communicable diseases. This requires urgent intervention. The aim of this study was to investigate the associations of physical activity with cardiovascular fitness in a cross-sectional retrospective observational fashion. Data were collected for 21 years from 2530 healthy volunteers and athletes representing the entire spectrum of physical activity from the totally inactive sedentary persons to the highly trained national athletes.
Methods: Cardiac fitness was investigated echocardiographically, which is characterized by reduced resting heart rate (RHR), increased relative left ventricular muscular mass (rLVMM), improved left ventricular diastolic function (characterized by the ratio of early to late ventricular peak velocities, E/A) and peak exercise oxygen consumption.
Results: We found that even moderate exercise is associated with improved cardiac characteristics. With increasing exercise level, the RHR decreased from 69 to 63.3, 61.4, 58.6, 56.1, and 55.8/min in non-athletes, leisure athletes, lower class athletes, 2nd class athletes, 1st class athletes, and national athletes, respectively. While the rLVMM was increased from 64.6 to 70.7, 76.3, 78.5, 86.7, and 88.9 in the same groups. The E/A ratio also increased from 1.71 to 1.72, 1.85, 2.04 in the non-athletes, leisure athletes, lower class athletes, and 2nd class athletes, respectively, but then decreased to 1.92 and 1.98 in the 1st class athletes and national athletes. The largest exercise-induced improvement of cardiac fitness was observed between the inactive and the least active group, which did not increase further in the highly trained national athletes enduring up to 20 training hours per week.
Conclusions: Our findings indicate that cardiac fitness can be improved by moderate exercise in sedentary persons. This information would help physicians to encourage inactive patients, who find physical exercise intimidating, for doable and sustainable behavioral change.