[Effect of aerobic endurance exercise on immune function in elderly athletes]

Recently, there have been several reports on the influence of physical activity on immune function. Most of the studies were conducted using maximal exercise in young and middle-aged subjects. Since human immune function undergoes adverse changes with aging, we investigated in the present study whether submaximal, aerobic exercise induces changes in immune function in elderly subjects. Leukocytes, differential blood count, subsets of lymphocytes, CD4/CD8 ratio and immunoglobulins were studied after submaximal aerobic exercise (mean lactate 2.57 + 0.3 mmol/l) in 15 elderly subjects (mean age 68 +/- 5.6 years). These parameters were measured before, immediately after and 4 hours after exercise. Mean hemoglobin was unchanged indicating no hemoconcentration. There was a small increase in mean total lymphocytes (p < 0.05 immediately after exercise), while there was a highly significant increase in leukocyte count both immediately and 4 hours after exercise (p < 0.01). We found a significant correlation between the increase in leukocytes and lactate concentration (p < 0.01, r = 0.784). Lactate levels of all subjects were below 4 mmol/l. These results might indicate that the effect of a single bout of aerobic exercise on immune function depends on the intensity and duration of exercise relative to the level of fitness in elderly subjects. There was a highly significant rise (p < 0.001) in CD4/CD8 ratio 4 hours after exercise. This increase was mainly due to a rise in CD4 cell number whereas T-suppressor cells were almost unchanged. Our data show a possible stimulation of immune function by a submaximal, aerobic exercise in elderly subjects. Further studies are required to clarify whether a stimulation of CD4/CD8 ratio by chronic training gives rise to a reduction of infections in physically active elderly persons.