Effects of 6 months of moderate aerobic exercise training on immune function in the elderly

The purpose of this study was to determine the effects of 6 months of moderate aerobic exercise on age-dysregulated measures of T lymphocyte and natural killer (NK) cell number and function. Previously sedentary elderly (age=65±0.8 years) subjects were randomly assigned to supervised 3 time/week exercise intervention group (EXC, n=14) or flexibility/toning control group (FT-CON, n=15). Fasting resting blood samples were drawn prior to and after the 6 month intervention. The EXC group exhibited a significant (P<0.05) 20% increase in VO₂ max, whereas the FT-CON group had a smaller non-significant (P=0.07) increase (9%). Immune results revealed that, in general, changes in immune function in response to 6 months of exercise training at an average intensity of 52% heart rate reserve (HRR) were similar when compared to FT-CON who exercised at ~21% HRR. There were no intervention-induced changes in total white blood cell, neutrophil, lymphocyte, monocyte, eosinophil, or basophil blood counts. Furthermore, the percentage and number of CD3⁺, CD4⁺ and CD8⁺ T cells in the blood remained unchanged. There was a tendency for the percentage and number of CD4⁺ and CD8⁺ naive cells (CD45RA⁺) to increase and for CD4⁺ memory cells (CD45RO⁺) to decrease post-intervention, especially in FT-CON. Both groups exhibited a small intervention-induced increase in the T-cell proliferative response to mitogenic stimulation; the percentage change of which was higher in the EXC group at several doses of Con A. Unstimulated NK cell cytolysis versus K562 cells tended to increase (P<0.1) in the EXC group with little change in FT-CON. We conclude that 6 months of supervised exercise training can lead to nominal increases in some measures of immune function, while not affecting others, in previously sedentary elderly. Copyright (C) 1999 Elsevier Science Ireland Ltd.