Abstract
This study determined the effects of 10 weeks of intensive swimming 0, 1,5, and 10
times per week on relative coronary circumference index (RCCI), which was calculated
as the ratio of cardiac ventricular weight to the sum of the circumferences of the
right and left main coronary arteries. Sixty-nine Wistar rats swam continuously for
30 to 51 min per session while carrying 1.0% to 2.25% of their individual body weights.
Hearts were prepared using routine histological methods and were analyzed for RCCI,
coronary circumference, heart mass, and regressed heart mass. Data were analyzed for
linear, quadratic, and cubic trends relative to exercise frequency. Mean values for
wet weight RCCI were 98.82, 99.16, 91.04, and 90.21 mg per planimeter unit for groups
exercising 0, 1, 5, and 10 times weekly (P < 0.01 for linear trend). Regressed mean ventricular dry weights exhibited expected
significant linear increases of 4.89%, 5.66%, and 6.12% over sedentary control rats.
The RCCI was clearly shown to undergo a significant linearly graded decrease with
increasing frequencies of exercise.
Key words
exercise frequency - coronary circumference - cardiac hypertrophy - myocardial blood
flow
