Obesity is regarded as one of the risk factors for lifestyle-related diseases. The obesity level is usually evaluated by Body Mass Index (BMI). However, BMI does not necessarily represent exact amount of fat in the body. Use of body fat percentage may be desirable to determine the obesity level, but it is virtually impossible to define the degree of obesity unless criteria of an "ideal" body fat percentage are established. Because obesity, as well as physical activity, is closely related to hemodynamics, the reaction of the hemodynamics to exercise load was investigated for 25 young Japanese female subjects according to body fat percentage. Body fat percentage was classified into the following four groups: "thin, ""ideal, ""borderline" and "obese", and systolic blood pressure and pulse rate changes in response to exercise load were analyzed by these four groups. From the analyses on the changes in the measurement waves, six and four patterns were ascertained for the systolic blood pressure and pulse rate, respectively. Majority of the subjects in the two categories, "ideal" and "borderline, "showed similar characteristics, with the designated type "a" for the systolic blood pressure (which showed a single-stage symmetrical left-right rise), and type "A" for the pulse rate (indicating a two-stage rise). As a future topic, we would like to report on what data can be obtained concerning the blood circulatory system based on classification of systolic blood pressure and pulse rate wave patterns. Because significant or mildly significant differences were recognized in the rates of change and overall degree of change in both systolic blood pressure and pulse rate, these were subjected to analysis. The rates of change and overall degree of change in systolic blood pressure became progressively greater from "thin" to "borderline" groupings, but then conversely in the "obese" grouping became smaller . Because both the rates of change and overall degree of change among those in the "borderline" grouping were greater than those in the other three groupings, it may be possible that those in this "borderline" grouping would have the lowest rate of mortality due to cardiovascular disease. Further, the rates of change and overall degree of change in pulse rate, while relatively small from the "thin" grouping to the "ideal" grouping, became slightly greater in the "borderline" grouping and then reverted to smaller in the "obese" grouping. Because no significant differences were observed in the rates of change and overall degree of change in pulse rate between the "ideal" grouping and "borderline" grouping, no necessity was seen in segmenting these two groupings based on body fat percentage. In the "ideal" and "borderline" groupings, the pulse rate is considered to increase at moderate rates up to maximum cardiac output, which is believed to indicate the effective vital reaction to exercise load.
