Relation between changes in serum hypoxanthine levels by exercise and daily physical activity in the elderly

Effect of exercise at mild intensity on the serum levels of hypoxanthine wa s studied in eleven healthy elderly subjects. They were divided into the ac tive and sedentary groups according to their daily physical activity. They performed exercise testing to walk for 5 minutes keeping heart rate at appr oximately 70% of the maximum heart rate. Mean intensity of exercise estimat ed according to Karvonen's formula in the active or sedentary group was 41. 8 +/- 9.6% or 34.1 +/- 6.1%, respectively. In the sedentary group, the seru m hypoxanthine levels at 10 minutes after completion of walk load was signi ficantly higher than that before exercise. Changes in the serum hypoxanthin e levels in the a,active and sedentary groups were -0.97 +/- 1.36 and 0.80 +/- 0.57 mu mol/liter, respectively (p < 0.05). This result suggests that m ild intensity exercise increases the serum hypoxanthine concentration in th e elderly leading inactive daily life, and physical activity suppresses an increase in the serum hypoxanthine levels by mild exercise. hypoxanthine; e xercise; physical activity (C) 1999 Tohoku University Medical Press.