The influence of sagittal trunk leans on uneven running mechanics

Journal article


AminiAghdam, S., Reinhard, B. and Karamanidis, K. (2021). The influence of sagittal trunk leans on uneven running mechanics. Journal of Experimental Biology. 224 (1). https://doi.org/10.1242/jeb.228288
AuthorsAminiAghdam, S., Reinhard, B. and Karamanidis, K.
Abstract

The role of trunk orientation during uneven running is not well understood. This study compares the running mechanics during the approach step to and the stepdown of a 10-cm expected drop, positioned halfway through a 15-m runway, with that of the level step in twelve participants at a speed of 3.5 m/s while maintaining self-selected (17.7±4.2°; mean±S.D.), posterior (1.8±7.4°) and anterior (26.6±5.6°) trunk leans from the vertical. Our findings reveal that the global (i.e., the spring-mass model dynamics and centre-of-mass height) and local (i.e., knee and ankle kinematics and kinetics) biomechanical adjustments during uneven running are specific to the step nature and trunk posture. Unlike the anterior-leaning posture, running with a posterior trunk lean is characterized with increases in leg angle, leg compression, knee flexion angle and moment, resulting in a stiffer knee and a more compliant spring-leg compared with self-selected condition. In the approach versus level step, reductions in the leg length and stiffness through the ankle stiffness yield lower leg force and centre-of-mass position. Contrariwise, significant increases in the leg length, angle and force, and the ankle moment, reflect in a higher centre-of-mass position during the stepdown. Plus, the ankle stiffness significantly decreases, owing to a substantially increased leg compression. Overall, the stepdown appears to be dominated by centre-of-mass height changes, regardless of having a trunk lean. Observed adjustments during uneven running can be attributed to anticipation of changes to running posture and height. These findings highlight the role of trunk posture in human perturbed locomotion relevant for design and development of exoskeleton or humanoid bipedal robots.

KeywordsTrunk posture; Uneven running; Spring-mass model; Leg stiffness ; Joint stiffness
Year2021
JournalJournal of Experimental Biology
Journal citation224 (1)
PublisherThe Company of Biologists
ISSN0022-0949
Digital Object Identifier (DOI)https://doi.org/10.1242/jeb.228288
Web address (URL)https://jeb.biologists.org/content/early/2020/11/26/jeb.228288
Publication dates
Print06 Jan 2021
Online30 Nov 2020
Publication process dates
Accepted19 Nov 2020
Deposited01 Dec 2020
Accepted author manuscript
License
File Access Level
Open
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