Fast Motion Speed Alters the Sit-to-Walk Spatial and Temporal Pattern in Healthy Young Men.

Sit-to-Walk (STW) is a critical task for daily independence, yet its two inherent destabilizing events (seat-off, walking initiation) may diminish postural stability under fast motion speed (FS). This study aimed at the FS effect on the STW spatial and temporal patterns, with a specific interest in the relative STW temporal pattern. The STW kinetics and kinematics were recorded (n=18 men, 20.7±2.0 years) at preferred and FS. Statistics included One-Way repeated measures ANOVA (SPSS 25.0, p≤0.05). The FS spatial pattern reveals a discontinuous mode of the forward ground reaction force, indicating a balance rather than a propulsive strategy during the Rising phase. The FS relative temporal pattern reveals the prolongation of the Leaning phase (most possibly due to the feet repositioning), the shortening of the Rising and the Walking phases, and a relative delay in the spatial variables (p≤0.05). Overall, the results do not allow the STW consideration at FS as a "magnified" with respect to force, or a "shrinked-in" with respect to time, copy of the preferred motion speed. As more generic and versatile than the absolute one, the relative temporal pattern may be used as a reference for a variety of populations.

Inertial sensing of the motion speed effect on the sit-to-walk activity.

The STW execution at motion speed faster than normal most possibly enhances the risk for balance loss due to the increase in body segment accelerations. The purpose of the study was to use inertial sensing to examine the effect of motion speed on the STW segmental kinematics and its temporal events. Eighteen young men (20.7 ±â€¯2.0 years) performed STW trials at preferred (PS) and fast (FS) motion speed. Data were collected with Xsens inertial sensors positioned at the trunk, thigh, shank, and foot segments. The maximum segmental values of angular displacement, angular velocity and linear acceleration, the duration of total STW (ttotal), the absolute and relative (% ttotal) phase duration (Flexion, Transition, Extension, Walking) and, the absolute and relative time taken to reach each maximum value were determined. In FS, ttotal and the absolute phase duration (except for Transition), were all significantly shorter (p = 0.000). The relative phase duration was not altered (p > 0.05), except for the Extension shortening (p = 0.001). The maximum angular displacement was altered only for the thigh (decreased, p = 0.038) and shank (increased, p = 0.004). Maximum angular velocities and linear accelerations were all significantly increased (p = 0.000 for all). The absolute time to reach the maximum values shortened in FS (p ≤ 0.05), while, the relative times were not altered (p > 0.05), except for the delayed trunk maximum angular displacement (p = 0.039). Inertial sensing appears to identify the motion speed effect on STW segmental kinematics and their temporal events in healthy young men. The results of the study may contribute improving the preventive or rehabilitation interventions in persons with impaired postural control.