Few data are available regarding the effects of exercise training upon cardiac structure and performance in man. We evaluated the echograms of 24 normals before (PRE) and after (POST) 11 weeks of endurance exercise training. Conditioning consisted of a walk-jog-run protocol at 70% maximal heart rate for one hour four days per week. Training reduced heart rate and increased maximal duration and estimated oxygen consumption of treadmill exercise. Compared to PRE, the echogram in the POST training period revealed an increased left ventricular (LV) end-diastolic dimension (EdD), a decreased end-systolic dimension (EsD) and thus an increased stroke volume (EdD3-EsD3) and shortening fraction (EdD-EsD)/EdD). Cardiac output (CO) and peripheral vascular resistance (BP/CO X 80) were identical PRE and POST conditioning. Importantly, an increase in mean fiber shortening velocity was observed POST training as were increases in LV wall thickness, ECG voltage of S in V1 + R in V5, and LV mass. Thus endurance training was accompanied by increases in both LV dimension and mass as well as LV shortening fraction and contraction velocity as observed by echocardiogram.

During the past twenty years there has been a great increase in the number of blood transfusions administered, and the recent use of normal and lyophilized serum in combating shock and in restoring the plasma proteins to their normal level promises to increase still further the already great demand for blood. In spite of the frequent use of whole blood and blood serum there have been surprisingly few studies on the rate of hemoglobin regeneration in the blood donors. Most of the recorded observations have been made on groups of professional donors who have given varying amounts of blood over a period of months or years, and the reports have been concerned with the hemoglobin and erythrocyte levels after multiple donations. Giffin and Haines 1 studied 84 donors, many of whom had given blood for 20 or more transfusions, and concluded that donations of 500 cc. of blood at intervals of four to five weeks are not harmful to male donors but that in female donors anemia often develops under similar conditions. Powell= studied 25 donors, 1 of whom had given blood for 63 transfusions, and found that anemia had devel¬ oped in only 2 of the group. Jones, Widing and Nelson 3 studied 50 donors who had given blood for a total of 175 transfusions and found that the blood hemoglobin level rapidly returned to normal. Certain donors exhibited such regenerative ability that the withdrawal of 1,200 to 2,000 cc. of blood within a period of one to twenty-three days was followed by a return of the hemoglobin level to normal within ten days. Martin and Myers4 found an average reduction of 310.000 in the erythrocyte count and a 5.2 per cent drop in the hemoglobin level following the removal of 500 cc. of blood. The minimum values were found six hours after the bleeding. No ill effects were noted in 10 donors who had given blood for a total of 52 transfusions, but Martin and Myers expressed the belief that blood should not be taken more frequently than every three months. They too noted that hemoglobin regeneration is slower in female than in male donors. The same interval, three months, between blood donations was recommended by Brewer 5 after observations on 1,076 donors, although he found that the hemoglobin had returned to its normal level at the end of two months in most donors. Cadham°found that six months after the withdrawal of small amounts of blood for trans¬ fusions of convalescent serum there was no anemia and most of the subjects felt better than they had prior to the blood donations.Less encouraging reports have been given by other investigators,7 who have found instances of persistent anemia after repeated donations of blood, and in some cases8 a reduction in the leukocyte count has been noted. A study of 101 Chinese donors9 revealed a reduction in the blood hemoglobin that paralleled the amount of blood withdrawn and the time that the subject had been serving as a blood donor. The anemia was of the microcytic type, and glossitis, achlorhydria and splenomegaly were occasionally encountered. The slower hemopoietic response i...

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