Three-Dimensional Kinematic Characterization of An Object Pick-Up Task Using Motion Capture

Summary

This protocol presents a standardized full-body motion capture approach for assessing the object pick-up task, illustrating how distinct movement strategies and compensatory patterns can be quantitatively characterized during this common functional activity.

Abstract

The object pick-up task is a fundamental activity of daily living that integrates trunk, lower- and upper-limb coordination, balance, and visuomotor control within a single, ecologically valid movement. Despite its relevance, standardized protocols for quantitatively assessing object pick-up strategies using full-body motion capture remain limited. The goal of this protocol is to demonstrate a standardized method for capturing and analyzing the object pick-up task using full-body three-dimensional motion capture and to illustrate how different movement strategies can be identified and classified. The protocol details participant preparation, comprehensive marker placement, task execution, and representative kinematic analyses. Thirty participants performed the object pick-up task, during which fourteen kinematic variables were collected. Movement strategies were classified into squat-dominant, hinge-dominant, and hybrid patterns representing distinct and intermediate approaches along a continuum of movement strategies. Representative results demonstrate clear differences in joint kinematics between strategy groups, particularly at the knee and ankle, with additional contributions from torso motion. Differences between dominant and non-dominant hand conditions further illustrate the task’s sensitivity to compensatory movement adaptations. This protocol provides a practical and reproducible framework for assessing object pick-up strategies and whole-body coordination during functional movement.

Introduction

Assessment of human movement is central to clinical and research evaluations of musculoskeletal and functional health¹. Traditionally, movement assessment has relied largely on visual observation, which, while clinically valuable, is inherently subjective, influenced by the rater experience, and limited in its ability to consistently capture subtle coordination patterns. Motion capture technologies, including both marker-based and marker less systems, allow detailed and quantitative examination of whole-body movement with increasing accessibility^2,3,4<....

Protocol

The study (IRB-2018-04-014) was approved by the institutional review board of Nanyang Technological University, Singapore and was conducted in accordance with the ethical standards set forth in the 1964 Declaration of Helsinki or comparable ethical standards. All participants provided written informed consent prior to participation.

1. Participant Preparation

NOTE: The task involves participants picking up a standardized object from the floor at a comfortable pace, returning to standing, and handing over the object, as described in Section 7.

1. Ask the participant to wear a singlet and ....

Results

Thirty participants performed the object pick-up task, during which 14 kinematic variables were collected. Participants were subsequently classified into three strategy groups representing distinct and intermediate approaches along a continuum of movement strategies, interpreted as squat-dominant (Group 1), hinge-dominant (Group 2), and hybrid strategies (Group 3). No statistically significant differences were observed between groups for age, sex distribution, height, or weight (Table 2). All participant.......

Discussion

This protocol demonstrates a standardized approach for capturing and analyzing an object pick-up task using full-body three-dimensional motion capture and illustrates how different movement strategies can be quantitatively characterized. Participants were purposefully selected and grouped to represent distinct and intermediate movement strategy patterns observed within the sample. Visual inspection of joint kinematics indicated that knee flexion magnitude was the primary differentiating feature, with overlap observed in .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Box for Pick up task	N/A	N/A	70mm x 70mm x 70mm (Lx W x H) 3D-printed using polylactic acid (PLA) filament (eSUN; Shenzhen Esun Industrial Co., China).
Cluster markers	Qualisys, AB	· 160146 Upper body · 160145 Lower body · 160149 SuperWrap for cluster	Clusters included two upper-body clusters (upper arms) and four lower-body clusters (two on the thighs and two on the shanks).
Cluster markers (custom)	N/A	N/A	Custom-designed cluster markers for tracking the wrist (RFA, LFA) and hand (RHMC, LHMC) were 3D-printed using polylactic acid (PLA) filament (eSUN; Shenzhen Esun Industrial Co., China).
Computer workstation	Generic	NA	Intel Core i9 processor, 32 GB RAM, 10 TB Harddisk, NVIDIA RTX2080
Double-sided adhesive skin tape	Qualisys, AB	160188 Double-sided adhesive tape	For attaching marker base to skin
Force plate	Kistler	Type 9260AA6	Two plates (600 × 500 x 50 mm) embedded underneath the flooring, one for each foot.
Hypoallergenic adhesive skin tape	3M	Micropore
Marker base	Optitrack	M4 Marker base
Motion capture system	Qualisys, AB	Miqus Video Aqus A12	x2, Full HD / 2 MP, Resolution 1920 × 1080 x12, 12 MP 300fps, Resolution 4096 × 3072, FOV 54 × 42 °(motorized)
Neodymium Magnets	Generic	N/A	Diameter 15mm, Thickness 1mm
Qualisys Track Manager (QTM)	Qualisys, AB	Version 2019	The software is used to record movements during the experiment and perform data post-processing.
Retroreflective markers	Optitrack	12.7 mm (1/2) M4 Markers
Visual3D	HAS-Motion	Version 2021	The software is used to do biomechanical modelling and produce the relevant joint angles