Studies on changes in physiological functions according to ageing

Abstract

1. Physiological age factor F as a mathematical indicator of losses of physiological functions resulting from ageing was calculated. Ten physiological functions, i. e. amplitudes of accommodation (right and left), mobility of shoulder joint, mobility of vertebral column, mobility of hip joint, standing broad jump, grasping powers (right and left), back muscular power and vital capacity were measured on 155 healthy adult males from 20 to 54 years of ages. Correlation coefficients between losses of these physilological functions and chronological ages were significant. Physiolgical age factor F was estimated by the centroid solution from the symmetric matrix, the elements of which were correlation coefficients between physiological functions. Correlation coefficient between physiological age factor F and chronological age was significant (r=-0.774). Physiological age factor F was decomposed into connective tissue factor F1' and parenchymatous cell factor F2'. 2. A group of old men in their 60, s was compared with a group of young men in their 20's in regard to body temperature regulating mechanisms, when they were nude in the recumbent position for 40 minutes in a hot environment (D.B. 36.2°C, W.B. 32.2°C). The results thus obtained were these: a) When a young group was exposed to hot temperature, rectal temperature showed a pronounced paradoxical initial fall. The temperature returned to the resting value 40 minutes after exposure to hot temperature. On the otherhand, the rectal temperature of an old group rose almost linearly instead of showing an initial fall. This fact may be interpreted as indicating that old men are inferior to young men in the velocity and intensity of increased heat convection caused by an increase in the skin blood flow in the hot environment. This is also supported by the fact that the increasing rate of initial skin temperature, thermal conductance and index of blood flowing through peripheral tissues in a young group are greater than in an old group. b) The time taken for a young group to sweat at a high temperature is shorter than the time for an old group. The rate of sweating of a young group was greater than that of an old group. The absolute value of skin temperature at the commencement of sweat secretion as well as a difference between absolute value and resting value were lower in a young group than in an old group. This applied to rectal temperature at the commencement of sweating. Therefore old men are inferior to young men both in the excitability of the sweating center and in the activity of the sweat gland. c) Heat storage per body weight in a hot environment was particularly greater in old men than in young men. 3. Analysis of the results of the step test in a total of 140 male adults ranging in age from 20 to 79 led to the following conclusions: a)According age advances from adolescence to old age via manhood, i) each of the indexes, which is the smaller the more inferior the physical fitness⃜initial increasing rate of the heart rate (I.I.R.), recovery rate of the heart rate (RP1 & RP2), oxygen pulses during exercise and following recovery [(O.P.)E2 & (O.P.)Rc1]⃜becomes smaller, and ii) each of the indexes which is the greater the more inferior the physical fitness gets…heart rate increment duringee xercise (PE & αE), ventilation coefficients during exercise and following recovery [(V.R.)E2 & (V.R.)Rc1], respiratory quotients during exercise and following recovery [R.Q.)E2 & (R.Q.)Rc1], excess CO2 output, R/E ratio, oxygen debt and oxygen requirement⃜becomes greater. © 1962, Japan Society for Occupational Health. All rights reserved.