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In order to search for the methods predicting energy metabolism and estimation of physical fitness as as index of heart rate having smaller measurement error and which would be simple to measure, this study was performed on healthy but unathletic males(aged 20∼25) during 20 minutes walking on a levle treadmill at 6 differentt speeds(2,4,5,6,7 and 9㎞/hr). Heart rate was measured during walking on a level treadmill and in a reating state using the telemeter of Heart Checker 108 System(Senoh Co., Japan). Oxygen uptake and CO_2 output were determined by collecting expired air into Douglas bag during one minute period after 15 minutes of walking, and during 5 miutes at a resting state. The air collected was gauged through a wet test gas meter(Precision Scientific Co., U.S.A.)and analyzed with Orsat gas analyzer(Fisher Co.,U.S.A.)into percentages of oxygen and CO_2. Then, respiratory quotient(R.Q.) and energy metabolism(㎉/hr/㎡)were calculated using caloride table of Zuntz and Schrumberg per body surface area. Oxygen uptake(ml)per kilogram of body weight on a minute at a resting state is defined as 1 Met, and ratios of oxygen uptake during steady state of the walking at 6 different speeds to that at a resting state were calculated. The followings are results obtained from the study: 1. Mean values of heart rate, oxygen uptake and calorie expenditure measured at steady state of each walking speed steadily increased in proportion with thw speed, and the optimal speed of walking was believed to be 4㎞/hr in reviewing rate of increament for these measurement at different speeds. 3. A close linear regressional relationship(y=198.0 x-2.23, r=0.9205:P<0.001)was observed between calorie expenditure(y:㎉/hr/㎡) and oxygen uptake(x:ℓ/min). Qnd these two measurements also showed close linear regressional relationships with heart rate(x: beats/min), the regression being expressed as y=3.62 x-201.9(r=0.8265:P<0.001) for the former, and y=0.0195 x-1.140(rp0.9571:P<0.001) for the latter. 4. Calorie expenditure during walking at a apeed of 2,4,5,6,7 and 9㎞/hr on a level treadmill when expressed in terms of Mets amounted to 2.7(≒2.5), 3.3(≒3.0), 4.1(≒4.0), 5.8(≒6.0),9.0 and 11.8(≒12).
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