Stand up and walk! Are we missing information about trunk movement?

B. Sánchez, Maria, Sanderson, Andy ORCID: https://orcid.org/0000-0002-7892-1067, Brown, Steven and Hodson-Tole, Emma ORCID: https://orcid.org/0000-0003-1200-1724 (2025) Stand up and walk! Are we missing information about trunk movement? In: Gait & Posture, pp. 212-214. Presented at European Society for Movement Analysis in Adults and Children (ESMAC), 8 September - 13 September 2025, Basel, Switzerland.

Published Version File not available for download. Available under License In Copyright. Download (990kB)

Abstract

Introduction The trunk represents almost 50% of the total mass of a person [1] and, because it comprises multiple segments, has a large range of motion [2]. Trunk posture and movement are important in the execution of activities of daily living (ADL), especially those related with arm function [3]. In movement analysis, the trunk is usually defined as a single rigid, segment between the shoulders and pelvis. This representation ignores the trunk’s large movement potential [2], preventing a complete evaluation of its movement; however, it is not clear how much information is missed when assessing performance of ADL. Research Question Are there differences in the movements quantified by a single- and multi-segment trunk model? Methods The University Ethics Committee (ref:47565) approved the project. Eleven people (7 male; (mean ±SD) age: 27.82 ±3.18years, height: 1.74 ±0.11m; weight: 75.0 ±12.7kg) participated after signing the consent form. An upper-body marker-set was used: left/right acromion, iliac-crest, ASIS; manubrium, S1; five inverted "L" clusters of 3 markers: two 2.5cm lateral either side of C7, T3, T7, T11 and L3, with the third marker on the long end of the "L" with the length adjusted based on the participant’ s size. These defined a single-segment-trunk (acromia to iliac-crests), and upper-, mid- and lower-thoracic, and upper- and lower-lumbar segments (multi-segment-trunk). Participants were asked to stand from a bench set so the thigh was parallel to the floor and walk towards the left. Motion capture data were recorded (100Hz), and analysed to provide segmental angles (in relation to the absolute coordinate system) in each trial. Change in each segmental angle [flexion-extension (X), inclination (Y), rotation (Z)] was calculated between the start of the trial and the maximum angle (part A), and between the maximum angle and the end of the trial (part B). A repeated measures ANOVA was done between the single-segment-trunk angles and each of the other segments. Results The statistical analysis showed no overall difference between the single-trunk-segment and each if the segments of the multi-segment-trunk for either part A or B. Looking at the independent components the analysis (figure 1) showed that for part A there was a mean difference between the single-trunk-segment and the upper-thoracic segment for component X of 26.13° (SE 3.4°); and for part B a mean difference with the upper-lumbar segment component X of -8.06° (SE 2.1°), and the lower-thoracic component Z of -29.42° (SE 17.8°), which is double the difference with the other segments. Discussion The single trunk model does quantify the general behaviour of the trunk during the tasks assessed. There is variation in the amount of movement occurring across the different segments, but how useful this additional information is, or what it may contribute to, is yet to the determined.