The importance of habitual exercise is generally accepted in modern society to keep and improve health and physical fitness. And it is also important to evaluate the effect of aerobic exercise to regulate its prescription. The present authors tried to debate on the adequate intensity and duration of aerobic exercise in middle-aged house-wives who were prone to be so-called hypokinetic diseases.
　The subjects were 9 healthy adult women, engaged in house keeping, whose age ranged from 24 to 44 years. As the exercise was adopted cycling on the outdoor course. The observation were made laying stress upon changes in respire-circulatory functions and adreno-sympathetic systems. As for indices of physiological work load, heart rate, blood pressure, respiration rate and RPE were recorded during the whole course of 30 min aerobic cycling, and besides, some urine tests were carried out.
　The results of the present experiment as summarized above seem to suggest that the 30 min aerobic cycling as a recreational sport gives sufficient exercise stress, activating the physiological functions of middle-aged house-wives without exercise habit. The authors, therefore, were led to the conclusion that the utilization of cycling in daily life can be recommended as an effective activity to improve the physical fitness, if the cycling exercise performed as perceived "somewhat hard" or "hard" subjectively.

DESCENTE SPORTS SCIENCE Vol.1/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE