2020 Volume 33 Issue 2 Pages 145-159
This study aimed to clarify the step variables and three-dimensional joint kinematics of the pelvis while increasing running speed on a treadmill. Sixteen male track and field athletes ran on an instrumented treadmill at three different running speeds: 4.0, 6.0, and 8.0 m/s. The step variables, such as step frequency, step length, contact time, and flight time, and the kinematic data of each running speed were recorded using a high-speed video camera (300 fps) and a Vicon T20 system (250 Hz). In addition, the pelvic angular displacement (Δ) was calculated by subtracting the minimum from the maximum values of the pelvic angle in the stance phase. The results were as follows: (1) Stride length and step frequency were significantly greater at higher running speeds. Although contact time was significantly shorter at the faster speeds, flight time was significantly shorter when transitioning from 6.0 to 8.0 m/s and from 4.0 to 8.0 m/s. (2) The pelvis of the swing leg side elevated from toe off to early half of swing phase with increasing running speeds. In addition, the pelvis of the stance leg side rotated to the swing leg side from mid stance phase to toe off with increasing running speeds. (3) Δelevation showed a significant negative correlation with step frequency but a significant positive correlation with stride length for each running speed. In addition, Δrotation showed a significant positive correlation with step frequency but a significant negative correlation with stride length at 8.0 m/s.
Therefore, increased pelvic elevation improves the stride when transitioning from a low to high speed, and increased pelvic rotation leads to a higher step frequency during the stance phase when running at 8.0 m/s. In addition, it was suggested that it is necessary to run at minimum 8.0 m/s for the pelvis to behave differently compared with running at slower speeds to learn the high speed running movement.