Abstract
Changes in blood capillary distribution were studied in skeletal muscle after endurance exercise. Sixty male rats were divided into two groups; an exercised and a non-exercised group. The exercised group was given tredmill running one hour per day for two months, starting two months after birth.
Usually, skeletal muscle fibers are classified into white, red and intermediate fibers. Most of the changes which were observed after endurance exercise were in the red muscle fibers.
The results were as follows: 1) As for the number of blood capillaries per unit area of muscle cross section in specimens the exercised group showed 50 percent higher than in the non-exercised group. 2) Capillary to muscle fiber ratios (C/F ratio) were calculated in different cross section. The C/F ratios in superfisial layers were lower than those in deep layers. 3) According to electron microscope observation, fine structural changes of blood capillaries in skeletal muscle displayed the following two characteristics. First: multiplication of the blood capillaries was accompanied by changes in the endothelium. Second: the formation of bloos capillaries depened on changes in the interstitium which formed fibrous meshs around the plasma.
