[Effects of aging on respiratory function: with special reference to timed vital capacity].

In order to study the effects of aging on the respiratory function, the examinations were made on the forced vital capacity (FVC), % forced vital capacity (%FVC), peak expiratory flow (PF), and forced expiratory volume in 1 second (FEV1.0%). A total of 427 healthy male ranging in age from 22 to 59 years served as the subjects of the present study. The following were the results of this investigations. 1. The results of the measured values for FVC, %FVC, PF and FEV1.0% by age group showed a decrease in accordance with becoming older, thus showing a negative correlation with aging. 2. The major component analysis and the discriminant analysis were made for each of the above measurement items and the discriminant function Z was obtained by the following formula: Z = 0.177 x (age) + 0.0001 x (FVC) - 0.006 x (% FVC) - 0.009 x (FEV1.0%) - 0.023 x (PF) - 5.238. The discriminant border value Z was 0.244, which divided the subjects into two groups; the young (22-37 years of age, N = 245) and the middle aged (38-59 years of age, N = 182). 3. Some discriminant features were also observed within the middle-aged group between the younger (38-49 years of age) and the older (50-59 years of age) sub-groups. In evaluating the effects of aging on the respiratory function, three age-groups rather than two (young and middle-aged) maybe useful in many respects. 4. With the young group, there observed no correlations between the aged and each of the measurement items.(ABSTRACT TRUNCATED AT 250 WORDS)