The purpose of this study is to observe the effects of meal time on the carbohydrate and lipid metabolism during aerobic exercise. Four healthy female college student (21 to 22 years of age) were given steady state aerobic exercise of the moderate intensity by bicycle ergometer for 30 minutes. With regard to timing of meal and exercise, they were loaded with two types of exercise, (1) before-meal-exercise, which was practiced just before taking their lunch on a nearly empty stomach. (2) after-meal-exercise, which was practiced just after taking breakfast or lunch on a nearly full stomach. Venous blood was sampled immediately before starting exercise, immediately after and 60 min. after exercise, and blood glucose, lactate, triglycerides (TG), free fatty acids (NEFA) and proteine in the plasma were measured as well as the gas metabolism during the exercise.
　Main results obtained were as follows:
　1) Blood glucose levels just before the exercise of both types were within normal range, and decreased significantly just after the exercise, then recovered to pre-exercise level at 60 min. after the exercise. Blood lactate levels were not in excess of anaerobic threshold of 4mM/I in any type of exercise.
　2) Pre-exercise level of plasma NEFA, which was maintained at higher level within the normal range, decreased significantly just after the exercise in case of before-meal-exercise. Then, after taking lunch, it was maintained rather at the lower level. In case of after-meal-exercise, pre-exercise level of plasma NEFA, which was at lower level, tended to decrease still more. Plasma TG did not show any significant change between the values of pre- and post-exercise in both types of exercise.
　3) Hemoglobin content and plasma proteine showed no significant change between the values of pre- and post-exercise in both types of exercise.
　4) Oxydation ratio of carbohydrate and lipid, calculated from RQ in the gas metabolism during exercise, was approximately fifty-fifty in case of before-meal-exercise. Ratio of fat oxydation in case of after-meal-exercise showed no significant change comparing with that in case of before-meal-exercise, but it was inffered the tendency of slight decrease in their mean values.
　5) From the above mentioned results, it was suggested that the efficient (highly fat oxydative) exercise program, containing intensity, duration as well as timing of meal and exercise, is not easy to prescribed for the purpose of reducing the body fat and moreover improving the health.

DESCENTE SPORTS SCIENCE Vol.10/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE