The blood lactic acid (B. L. A.), the oxygen pulse per 1 kg. B. W. (O_2 pulse) and the shape of pulse rate curve (P. R. C.) at the early stage of test-work were studied with four castrated adult goats. These three were measured one hour after the end of preceding-work ─── 30 and 60 minutes' walking on the horizontal treadmill with a draft of 20% body weight.
The principal results obtained are as follows:
1. It is considered that the B. L. A., O_2 pulse and P. R. C. mesured after work can be used as indices showing the degree of fatigue.
2. The correlation coefficients obtained among these three are significantly high when we calculate B. L. A. by mg % or % of resting value, O_2 pulse by % of resting value and P. R. C. by the value of <(b+c)/2> - a [a, b and c are pulse rates per minute measured at 2 min., 4 min. and 6 min. respectively after the test-work was started].
3. As the correlation existing between P. R. C. and B. L. A. is the highest, it is suggested that the shape of pulse rate curve at the early stage of test-work is mostly depend upon the lactic acid accumulation in blood.
4. When we are to use these value as indices of fatigue, it seems to be suitable that we express B. L. A. by mg %, O_2 pulse by % of resting value and P. R. C. at the early stage of test work by the value of <(b+c)/2> - a.