Unlike other mammals' four limbs, man's upper limbs and lower limbs have been clifferenciated by the functions they perform respectively. However, as in the case of tetrapods, the coordination of all the fourlimb movement is a no less important consideration when it concerns the running movement of man. Therefore, the motions of man's upper- and lower-limbs need to be seen as closely related to each other instead of as distinct from each other.<br>What this study attempts to do is to clarify some of the characteristics of man's fourlimb movement when he is engaged in long distance running. The method adopted here is to analyze the order and intervals of the four-limb movement as seen in some of the marathon runners who participated in the 21st Fukuoka International Marathon in December, 1986. The data, a recorded videotape of the distance runners, was taken from the pictures telecast on the spot by NHK. The study subject was J. Ikangaa (subj. IK), the champion of this marathon race. An analysis is made with a careful observation of the constellation of the moments when each of his four limbs-the left upper arm, the right upper arm, the left thigh and the right thigh-began to protract. Some of the other runners' movement are also analyzed in the same way so as to serve as data on the control group.<br>The results obtained are as follows:<br>1) The sequential movement of the four limbs observed among subj. IK and all the runners in the control group proved to be of the "forward cross type". The order of the four limb movement, according to the definition of the "forward cross type" (IWA- MOTO and TOMITA, 1966), can be described like this. As the right lower limb begins to move, the contralateral left upper limb begins to move slightly later, after which the left lower, then the right upper limb begins to move and this completed sequence of movement is repeated in a cyclic pattern. This seems to illustrate the fact that since the lower limbs support the body weight and serve as the major propulsive force in bipedal running, the movement of each of the lower limbs precedes that of the upper limb contralateral to it.<br>2) In the running movement of each marathon runner, the intervals of four-limb movement were bilaterally asymmetric, and the intervals between ipsilateral upper- and lower-limb movement of both sides were somewhat longer than those of the two diagonal set of limbs.<br>3) Each runner's movement time of one cycle running was nearly steady. But the rate of the movement intervals between two diagonal set of limbs varied considerably throughout the course of the marathon.<br>4) Subj. IK's pitch of running was high (188-203steps/min.). And the movement intervals between his two diagonal set of limbs were significantly smaller than those of the other runners. His movement pattern of four limbs in running often showed a considerable resemblance to the "diagonal synchronous type".<br>5) On the way between the points of 20km and 30 km of this marathon course, the movement intervals of subj. IK's two diagonal set of limbs showed a small difference as compared with those of ipsilateral upper and lower-limbs of both sides. But at the 15km point, and on the way between the points of 30km and 38km of this marathon course, subj. IK showed a considerable decrease in the rate of the movement intervals between his two diagonal set of limbs.