Changes in acceleration and deceleration factors associated with active gait speed adjustment.

[Purpose] The ability to actively adjust walking speed is fundamental and the factors enabling it should be assessed. The present study aimed to demonstrate how active gait speed is kinematically adjusted. [Participants and Methods] Walking acceleration and deceleration were evaluated in 16 healthy adults using three-axis accelerometers and surface electromyographs. The root mean square (RMS) of each axis in the center-of-gravity acceleration was calculated as an index of gait stability. Electron myograph data were obtained from images captured of the right lower muscles, and the integral value of total muscle activity per gait cycle was calculated. [Results] The RMS of each axis increased during acceleration and decreased during deceleration. The integral values of total activity of the gastrocnemius, biceps femoris, and tibialis anterior muscles increased in acceleration. In contrast, the values increased in the biceps femoris but decreased in other muscles during deceleration. [Conclusion] These results suggest that the specific kinematic mechanisms of each factor regulate the acceleration and deceleration of walking. In addition, these mechanisms and factors indicate how exercise therapy may be used in rehabilitation to improve the ability to adjust walking speed in daily life.

Evaluating the immediate effect of the speed alteration task on walking stability using the Timed Up and Go test.

[Purpose] This study aimed to investigate how the speed alteration task, which gradually increases or conversely decreases walking speed, affected walking stability. [Participants and Methods] Thirteen healthy young adults performed two walking tasks as follows: the speed alteration task, in which the walking speed was gradually increased or decreased, and the speed constant task, in which the walking speed was maintained at a comfortable level. Before and after each task, the Timed Up and Go test was performed to analyze time, walking speed, and trajectory. The overall score of the Timed Up and Go test, as well as the scores of the three major segments (i.e., forward, turning around, and return), and nine subsegments, were calculated and analyzed. [Results] During the speed alteration task, parameters including time and walking speed of the Timed Up and Go test were significantly improved. Also, the same parameters increased significantly in the forward and return segments. These increases were also observed in the first subsegment of the forward segment and the second subsegment of the return segment. [Conclusion] The speed alteration task improved walking stability, so it could be used in gait training to improve walking stability.