Kinematic characteristics of manual guidance across expertise levels in a motion reproduction task: implications for physical therapist education.

[Purpose] We aimed to quantitatively evaluate manual guidance skills based on motion observation and identify kinematic characteristics associated with expertise in physical therapists. [Participants and Methods] Participants included skilled physical therapists, novice physical therapists, and individuals without experience in movement instruction. After observing an obstacle-avoidance reaching movement, participants reproduced the movement by manually guiding a humanoid model. We recorded fingertip kinematics using a three-dimensional motion analysis system and calculated absolute errors relative to the reference motion for movement time, trajectory length, peak velocity, acceleration, timing, and normalized jerk costs. After excluding participants with missing coordinate data, ten participants per group were analyzed. [Results] The skilled physical therapist group showed fewer errors in movement time, peak velocity timing, and negative peak acceleration timing than the other groups. The trajectory length did not differ among groups, and the normalized jerk cost error showed no significant group differences. [Conclusion] We found that expertise-related differences in manual guidance appeared more clearly in temporal parameters than in spatial trajectory or waveform structure. These findings suggest that temporal aspects of movement may represent one fundamental component of manual guidance expertise and may contribute to the development of objective evaluation methods and educational approaches in physical therapy.