Forty-eight male Wistar strain rats have been used to study the effect of voluntary exercise training on the succinate dehydrogenase (SDH) activity, blood lipids, and adrenal catecholamines. The animals were trained for 10 weeks with a voluntary running in revolving wheels. SDH activities in heart and skeletal muscles, total cholesterol and triglyceride in serum and adrenal catecholamines were determined right after rats reached a peak distance of voluntary running and at the end of training. Training produced no significant increase in the SDH activities of cardiac and skeletal muscles at 13 and 17 weeks of age. Physical training reduced 12%of serum cholesterol concentration (p<0.05) . The serum triglyceride concentration of trained group remained lower than that of the sedentary throughout a period of training (p<0.05) . The voluntary exercised rats had higher adrenal catecholamine concentration as compared with the sedentary at 13 weeks old (p<0.05), but there was no significant difference at 17 weeks old. These data demonstrated that voluntary training did not increase endurance capacity, and adrenal catecholamines, but lowered serum lipid levels.

The effect of chronic exercise on heart weights, succinate dehydrogenase (SDH) activities, and norepinephrine (NE) concentrations was examined in the Wistar-Kyoto (WKY) and Spontaneously Hypertensive (SHR) rats. Nine week old animals were trained either by forced treadmill running (26.8 m/min-1 hr/day) or voluntary exercise in running wheels (@9, 000 m/day at peak) for 12 wks. Male rats subjected to forced treadmill running program gained weight significantly more slowly than sedentary freely eating controls (p<0.01) . Heart ventricles of exercised groups in WKY rats were heavier than those of the sedentary controls (p<0.05) . Ratio of heart ventricle weight to body weight of male SHR and WKY rats was significantly higher in the runners than in the sedentary controls (p<0.01) . SDH activities of the red gastrocnemius muscle were 30 and 100% greater (p<0.01) for the voluntary and forced exercise animals, respectively, than the sedentary controls. Changes in muscle enzyme activity and heart weight were used to verify that the forced exercise program had produced a trained state. Blood pressure (BP) of voluntarily exercised SHR was 10% less at 15 wks (p<0.05) and remained lower until the end of training than that of control SHR, whereas BP of forced-trained SHR was not lowered. There was no measurable change in BP of WKY rats as a results of training. The voluntary exercise program had no effect on the concentrations of NE in heart and adrenal glands of SHR and WKY rats. The NE concentrations of heart and adrenal gland in forced/trained SHR and WKY rats were @10-40% greater than those of sedentary controls. The results of these experiments indicate that chronic exercise can depress the blood pressure of SHR rats. However, difference between two types of exercise training suggests that the endurance capacity improved by chronic exercise may not be a primary factor to delay the onset of the hypertention.

This study was designed to evaluate nutritional status of older endurance runners (age ; 62.5±2.5 yr., weight ; 53.8±4.2 kg, %fat ; 12.0±2.1%, mean±SD) by comparing with agematched sedentary individuals (63.6±3.5 yr., 58.4±9.1 kg, 15.6±4.0%) and middle-aged long distance runners (35.2±3.1 yr., 61.2±5.6 kg, 11.8±1.9%) . Average training distance of the older runners was a half of that of the middle-aged runners (44 vs. 85 km/week) . Maximal oxygen uptake in the older runners was significantly higher than in the older sedentary controls, but lower than in the middle-aged runners (50.4±4.1 vs. 30.6±3.5 vs. 64.0±2.2 ml/kg/min, respectively) . No differences were observed in the concentrations of serum albumin, serum iron and blood hemoglobin among the three groups. Intake levels of the three groups with regard to the major nutrients were sufficient as compared with the recommended dietary allowance appropriate for age, sex and physical activity level. Total caloric intake in the older runners was not remarkably higher than in the older controls in terms of kcal/day (2, 430 vs. 2, 230), but was significantly higher in terms of kcal/kg wt/day (45.5 vs. 38.9) . Percents to the total caloric intake of protein (15.2%), fat (25.4%) and carbohydrate (52.6%) in the older runners were almost identical to the other two groups. Ratios of animal to total in protein and fat were not significantly different among the groups. The intakes of calcium, iron, and vitamins A, B1, B2 and niacin were higher, but statistically not significant, in the older runners than in the older controls. These results suggest that nutritional status of older endurance runners is adequate for maintaining their health in a good state while keeping their active lifestyle.