Kinematics of shoulder, trunk, pelvis, and hip while reaching forward to progressively distant targets

Abstract

Introduction: Information on the normal contribution of various body regions to forward reaching provides a basis for assessing the maneuver. The purpose of this study was to describe the kinematics of the shoulder, trunk, pelvis, and hip of healthy young males while they stood and reached toward a target at arm's length and 5%, 10%, 15%, and 20% of body height beyond.

Method: Twelve healthy adult males were marked with 22 spherical reflective markers. Two trials of unilateral forward reaching were performed towards a target placed at five target distances. Motion was captured via reflective markers and an infrared camera system.

Results: Sagittal and transverse plane motions demonstrated high reliability between trials at each target distance (ICC = 0.716 trunk flexion to 0.977 shoulder flexion). Shoulder flexion and horizontal abduction were major contributors to forward reaching with components of trunk flexion and left trunk rotation at all target distances. Hip flexion, pelvic tilt, left pelvis rotation, and hip external rotation made notable contributions at the furthest targets. All motions became more pronounced as target distance increased (P ≤ .001).

Conclusion: Kinematic analysis demonstrated that right forward reaching requires composite movements at the shoulder, trunk, pelvis, and hip. The contribution of each body region to forward reaching became more pronounced as the target became more distant. These findings may be helpful when identifying localized movement impairments contributing to limited forward reach in a clinical population, although clinical validation is needed.

Keywords: Kinematics; Reaching; Upper extremity.