Kinematic control differs in walking speed adjustment to different velocities

[Purpose] To identify kinematic indices by performing acceleration/deceleration adjustment tasks and clarify the mechanism of walking speed adjustment. [Participants and Methods] Healthy adults with no history of orthopedic or central nervous system disease that could interfere with walking were included. Kinematic data with changes in walking speed were analyzed using a three-axis accelerometer, foot switches, and OptoJump Next. Two adjustment task experiments were conducted at different speeds: acceleration (Experiment 1) and deceleration (Experiment 2). The walking task constituted two conditions: walking at a comfortable speed and then shifting to the minimum speed as quickly as possible on a cue (minimum condition), and walking at a comfortable speed and then shifting to the intermediate speed as quickly as possible on a cue (intermediate condition). [Results] In Experiment 1, the step time and center-of-gravity acceleration in the front-back and left-right directions increased under the maximum condition for a longer period of time. In Experiment 2, the step length decreased earlier under the minimum condition; however, step time increased under the intermediate condition. [Conclusion] Kinematic control differs with adjustment to various target speeds. This study suggests that walking at a gait speed appropriate for a specific movement and environment can be improved through rehabilitation.