How does external lateral stabilization constrain normal gait, apart from improving medio-lateral gait stability?

Mohammadreza Mahaki; Trienke IJmker; Han Houdijk; Sjoerd Matthijs Bruijn

doi:10.1098/rsos.202088

How does external lateral stabilization constrain normal gait, apart from improving medio-lateral gait stability?

R Soc Open Sci. 2021 Mar 24;8(3):202088. doi: 10.1098/rsos.202088.

Authors

Mohammadreza Mahaki^{1

2}, Trienke IJmker², Han Houdijk^{2

3}, Sjoerd Matthijs Bruijn^{2

4}

Affiliations

¹ Department of Sport Biomechanics, Faculty of Physical Education and Sport Sciences, Kharazmi University, Tehran, Iran.
² Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, van der Boechorststraat 9, Amsterdam, NL-1081 BT, The Netherlands.
³ Center for Human Movement Sciences, University Medical Centre Groningen, University Groningen, The Netherlands.
⁴ Orthopaedic Biomechanics Laboratory, Fujian Medical University, Quanzhou, Fujian, People's Republic of China.

Abstract

Background: The effect of external lateral stabilization on medio-lateral gait stability has been investigated previously. However, existing lateral stabilization devices not only constrain lateral motions but also transverse and frontal pelvis rotations. This study aimed to investigate the effect of external lateral stabilization with and without constrained transverse pelvis rotation on mechanical and metabolic gait features.

Methods: We undertook two experiments with 11 and 10 young adult subjects, respectively. Kinematic, kinetic and breath-by-breath oxygen consumption data were recorded during three walking conditions (normal walking (Normal), lateral stabilization with (Free) and without transverse pelvis rotation (Restricted)) and at three speeds (0.83, 1.25 and 1.66 m s^-1) for each condition. In the second experiment, we reduced the weight of the frame, and allowed for longer habituation time to the stabilized conditions.

Results: External lateral stabilization significantly reduced the amplitudes of the transverse and frontal pelvis rotations, in addition to medio-lateral, anterior-posterior, and vertical pelvis displacements, transverse thorax rotation, arm swing, step length and step width. The amplitudes of free vertical moment, anterior-posterior drift over a trial, and energy cost were not significantly influenced by external lateral stabilization. The removal of pelvic rotation restrictions by our experimental set-ups resulted in normal frontal pelvis rotation in Experiment 1 and significantly higher transverse pelvis rotation in Experiment 2, although transverse pelvis rotation still remained significantly less than in the Normal condition. Step length increased with the increased transverse pelvis rotation.

Conclusion: Existing lateral stabilization set-ups not only constrain medio-lateral motions (i.e. medio-lateral pelvis displacement) but also constrain other movements such as transverse and frontal pelvis rotations, which leads to several other gait changes such as reduced transverse thorax rotation, and arm swing. Our new set-ups allowed for normal frontal pelvis rotation and more transverse pelvis rotation (yet less than normal). However, this did not result in more normal thorax rotation and arm swing. Hence, to provide medio-lateral support without constraining other gait variables, more elaborate set-ups are needed.

Keywords: arm swing; energy cost; external lateral stabilization; gait stability; pelvis rotation; step length.

Associated data

figshare/10.6084/m9.figshare.c.5344998
Dryad/10.5061/dryad.7pvmcvdrr