The relationship between cardiorespiratory exercise, immune function, and upper respiratory tract infection (URTI) was studied in elderly women utilizing a randomized controlled experimental design with a follow-up of 12 wk. Thirty-two sedentary, elderly caucasian women, 67 to 85 yr of age, who met specific selection criteria, were randomized to either a walking or calisthenic group; 30 completed the study. Twelve highly conditioned elderly women, 65 to 84 yr of age, who were active in endurance competitions, were recruited at baseline for cross-sectional comparisons. Intervention groups exercised 30 to 40 min, 5 d/wk, for 12 wk, with the walking group training at 60% heart rate reserve and the calisthenic group engaging in mild range-of-motion and flexibility movements that kept their heart rates close to resting levels. At baseline, the highly conditioned subjects exhibited superior NK (119 +/- 13 versus 77 +/- 8 lytic units, p < 0.01) and T (33.3 +/- 4.9 versus 21.4 +/- 2.1 cpm x 10(-3) using PHA, p < 0.05) cell function, despite no differences in circulating levels of lymphocyte subpopulations. Twelve weeks of moderate cardiorespiratory exercise improved the VO2max of the sedentary subjects 12.6 percent, but did not result in any improvement in NK cell activity or T cell function. Incidence of URTI was lowest in the highly conditioned group and highest in the calisthenic control group during the 12-wk study, with the walkers in an intermediate position (Chi-square = 6.36, p = 0.042). In conclusion, the highly conditioned elderly women in this study had superior NK and T cell function when compared with their sedentary counterparts. Twelve weeks of moderate cardiorespiratory exercise, however, was not associated with an improvement in immune function in previously sedentary elderly women.

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