EFFECT OF EXERCISE TRAINING ON CIRCADIAN RHYTHM OF THE ABSOLUTE RESTING METABOLISM IN MAN

Abstract

In the previous reports from our laboratory, we recognized that the oxygen consumption per unit of body surface area was generally higher in the athlete in contrast with the normal subject (nonathlete) even in the basal and resting conditiolls, and the metabolic rate in those conditions of both athlete and nonathlete exhibited a significant seasonal change characterized by higher level in winter and lower in summer. It is wellknown that many external stress-stimuli (such as heavy muscular exercise, cold and hot environment, etc.) produces a number of metabolic alterations, associated with adaptive changes of various internal organs including endocrine glands, especially adrenal cortex, thyroid gland and pineal gland. Further, since the muscular training causes a relative or absolute increase of metabolically active mass, or lean body mass, it may give rise to an elevation of total energy metabolism in the basal or resting condition for their ma intolerance, Unlike the seasonal change, the circadian rhythm is more intrinsic nature, coupled with the day-night cycles and reinforced by lesser factors such as temperature change. This rhythm, however, can be modified by some internal conditions such as diseases and drug administrations. Thus, it is of special interest to examine the effect of heavy exercise training on the circadian rhythm of energy metabolism in association with the rhythm of several other parameters.