Effect of Exercise on Coronary Tree Size in the Rat.

• It has been proposed by some that lack of physical exercise may be an important factor in the occurrence of coronary inadequacy of various types. Recently, Tepperman and Pearlman x developed a technique for estimating the size of the coronary tree in the rat from the weight of a vinyl acetate cast of the tree. Using this technique they observed that swimming for a period of 30 minutes twice daily caused a significant increase in coronarycast weight and a cardiac hypertrophy of borderline significance in rats. Our experiments were done to investigate this subject further and to ascertain the effects on coronary tree size of exercise of different types, frequency, and duration.