Effects of subjective effort on overground and treadmill running: a comparative analysis

Abstract

In this study, we investigated the differences in performance and kinematics between overground and treadmill running using the same amount of subjective effort. Fourteen female participants performed a 50-m sprint, running at maximum effort (100% subjective effort) as the maximal task on the ground. Subsequently, based on 100% subjective effort, they performed the grading task on the ground and on the treadmill at 30, 50, and 70% subjective effort. The running motion was recorded using a high-speed camera. We observed a significant difference in running velocity between the overground and treadmill conditions because treadmill running was recognized as having a greater load than overground running. The running velocity could be adjusted according to the subjective effort required for both overground and treadmill running. On the treadmill, running velocity was adjusted by maintaining flight time with increased subjective effort. Additionally, running velocity was adjusted by both step frequency and step length on the treadmill, whereas overground running velocity was adjusted by step frequency rather than step length. We also observed that overground, the knee angle was more flexible with an increase in subjective effort through one gait cycle, and the ankle joint was fixed at a high subjective effort. On the treadmill, the knee angle was adjusted only during the swing phase, and greater dorsiflexion was observed at high subjective effort.