In order to elucidate the changes of cardiovascular functions on the long distance running in middle-aged and old men (aged 40-87 years) performing the running training at least over a year measured on blood pressure and ECG before and after the 10km, 25km and 42km running, respectively. Furthermore, several runners fainted during and at the end of running were also measured on the blood pressure at the fainting. The results were summarized as follows,
In the 10km, 25km and 42km running the average values of systolic (excepting the 10km), and diastolic pressure after running were significantly lower than those average values before running. Further, it was noted that the higher the systolic and diastolic pressure before running were the more the reduction of those blood pressure after running in any distance, and also with the prolongation of running distance the reduction of those blood pressure became more remarkable. Especially, the reduction of blood pressure in the fainted runners was very remarkable. On the other hand, the pulse pressure showed no significant difference between before and after running.
On the observation of ECG recorded before and after running, the shortening of PQ interval and the prolongation of QTc were noted after running, especially the prolongation of QTc in a group of 42km was remarkable. While the reduction of T_II voltage was also found after running.
It may be therefore thought that a long distance running in middle-aged and old men bring on large changes for their cardiovascular functions, even if they continued the running training over a year.

Preliminary studies on the blood composition were carried out with 40- to 82-year-old runners when they were at rest. 790 male subjects who had kept the routine training of running over a year were examined. And the results were compared those with the corresponding control groups who had no particular routine training.
The results were as follows:
1. Runners' values for Red blood cell count and Hematocrit were decreased with age.
2. Runners' values for Red blood cell count, Hemoglobin and Hematocrit were approximately 10%, 9% and 4% lower than those of the corresponding control groups of almost all age groups. On the other hand runners' values for MCH (Mean Corpuscular Hemoglobin) were approximately 8% higher than the control group values for all age groups.
3. Runners' values for reticulocyte count and osmotic fragility of the blood were within normal range.
4. Comparison between runners of 10 km group and 25 km group of blood composition was made; the age group of forties of 25 km group of both Red blood cell count and Hematocrit were significantly lower than the corresponding 10 km group.
5. Dailly training programs of 25 km runners were significantly longer than those of 10 km runners for all age groups.

Physiological characteristics of middle-aged and old runners, who competed in the international 10km or 25 km race, were investigated. All of 2260 runners were aged 40 to 86 years. They have been trained for at least one years. Body composition, resting blood pressure, blood composition, serum metabolites, serum enzymes and pulmonary function were measured. The runners who competed in 10 km race were compared with those competed in 25 km race. Relation between running performance and physioloigical parameters were discussed.
1) Average running speed was faster in 25 km group than in 10 km group, although 25 km group ran a longer distance. In daily training, 25 km group also showed longer running distance than in 10 km group.
2) Body weight averaged 55.9±6.82 kg in a whole group of 2260 runners. Skinfold thickness averaged 6.1±2.50 mm in triceps, and 10.9±3.78 mm in subscuplar. These values were remarkably lower than normal values of corresponding age of the Japanese. 25 km group showed significantly lower values in these parameters than 10 km group. The runner who made better performance also showed lower values in these parameters.
3) Resting blood pressure of the runners averaged 144.3±17.0 mmHg in systole, and 86.2±11.0 mmHg in diastole. No difference were found between 10 km group and 25 km group in blood pressure.
4) RBC, Ht, Hb of 645 runners averaged 411.8±37.4×10⁴/mm³, 40.3±3.70%, 14.5 ±1.25g/dl, respectively. These values were lower than in normals. Among age group of 40-49yrs, negative correlation between running speed and these heamatological parameters were found. Better runner showed lower values in these parameters.
5) Blood glucose, serum choresterol, LDH and CPK were not different from normal values.
6) Pulmonary function were not different from normal values. Remarkable decrease with increasing age were found in pulmonary function.

The purpose of this study was to investigate the changes of blood components of middle and old aged runners in marathon running. The results were as follows.
1) Mean running time of marathon was 250 min. Some of subjects did last spurt.
2) Change of body weight was -4.8%. RBC, Hct, and Hb were changed by -4.8%, -4.4%, and -4.7% respectively. The decrease of plasma volume was 7.8% according to Dill's method.
3) Blood glucose was 112 mg/dl at rest and decreased to 70 mg/dl after running. The glucose level of five subjects was in range from 59 to 50 mg/dl.
4) The increase of L.A. was 52%. The L.A. after running tended to correlate to the running speed at last spurt.
5) T.G. significantly decreased after running. On the contrast, FFA increased by 323%. This increment of FFA correlated to mean running speed (r=0.681, P<0.05) .
6) The increments of GOT, GPT, and LDH were 71%, 62%, and 61% respectively, The decreases of LDH-1, 2 and increases of LDH-4, 5 were found after running. Furthermore, AGOT and 4GPT correlated to the running speed at last spurt or L.A. after running.