Short CommunicationCan toe-ground footwear margin alter swing-foot ground clearance?
Introduction
Tripping is the leading cause of falls sustained by older adults when walking [1]. Tripping is defined biomechanically as an event at which the most distal feature of the swing limb, usually the lowest part of the shoe, makes unanticipated contact with either the supporting surface or objects on it with sufficient force to destabilise the walker [2]. The risk of a tripping-associated fall is considered highest at minimum foot clearance (MFC), the mid-swing phase event at which the vertical displacement of swing foot from the walking surface is minimal [2], [3], [4].
Maintaining adequate MFC is, therefore, fundamental for tripping prevention [3]. Ankle dorsiflexion is the most effective lower limb joint angle modulation because a relatively small ankle angle change can considerably influence MFC with minimum disruption to gait control [5]. Few falls prevention strategies have, however, specifically targeted tripping-related falls.
Footwear design is an emerging consideration for safe outdoor walking to maintain the mobility of older adults [6]. The aim of this current study was to determine the effects of shoe forefoot design on foot-ground clearance. Minimum toe point (MTP) is the minimum vertical displacement of the swing toe at MFC (Fig. 1A). On a flat walking surface, most shoes provide a small vertical margin (VM) to MTP. In this paper effects of increased VM on swing foot-ground clearance were modelled using the virtual marker function [7].
To evaluate VM effects on swing foot-ground clearance, sagittal swing foot orientation was defined by the toe-heel angle relative to the horizontal. Given a typical sagittal ankle orientation at MFC the toe is lower than the heel. Based on the previous study [8], greater VM is hypothesised to increase foot-ground clearance. When the swing foot is parallel to the walking surface VM effects on increased swing foot-ground clearance are maximised (Fig. 1). Greater VM was, therefore, hypothesised to increase swing foot-ground clearance by aligning the shoe (operationally the toe rigid body) more parallel to the walking surface at MFC.
Section snippets
Data collection
A total of 150 right swing phase cycles (i.e. from toe-off to heel contact) of five healthy young males (height: 1.77 ± 0.07 m, body mass: 72.6 ± 14.0 kg) were analysed using three Optotrak Certus (Northern Digital Inc.) motion analysis camera units surrounding an 8 m walkway. The cameras sampled the two rigid bodies, each comprising 3 infrared light emitting diodes (100 Hz). The rigid bodies provided the position-time data to calculate sagittal plane kinematics of the right foot MTP and heel during
Results
Swing foot-ground clearances corresponding to the modelled values of VM = 0.2 cm and VM = 1.1 cm are described in Fig. 2(top). Effects of a 0.1 cm increase in VM on swing foot clearances over the swing phase were: +0.05 cm at toe-off; +0.06 cm at Mx1; +0.09 cm at MFC; +0.08 cm at Mx2 and +0.09 cm at heel contact (Fig. 2, bottom).
Fig. 3B visualises foot angle throughout the swing phase. Foot angle was greatest near toe-off but reduced to zero following MFC when the toe and heel were at the same height.
Discussion
Various shoe features have been investigated previously [6]. The current study demonstrated that vertical toe-height when standing (VM) combined with foot angle are important determinants of swing foot-ground clearance including the critical MFC event. Consistent with the experimental data [8], the current simulation confirmed that greater VM increases swing foot-ground clearance for a typical swing foot angle i.e., −90° < α < +90° (Fig. 3B) [4]. In relation to VM, smaller swing foot angle until
Conflict of interest statement
The authors do not declare any conflict of interest.
References (10)
- et al.
Ageing and limb dominance effects on foot-ground clearance during treadmill and overground walking
Clin Biomech
(2011) - et al.
Minimum foot clearance during walking: strategies for the minimisation of trip-related falls
Gait Posture
(2007) - et al.
Methodology for determining the sensitivity of swing leg toe clearance and leg length to swing leg joint angles during gait
Gait Posture
(2006) - et al.
Effects of ramp negotiation, paving type and shoe sole geometry on toe clearance in young adults
J Biomech
(2011) - et al.
Falls by elderly people at home prevalence and associated factors
Age Ageing
(1988)
Cited by (5)
3D-MFC: A method for computing critical gait parameters based on virtual marker tracking
2022, Proceedings - 2022 15th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics, CISP-BMEI 2022Effect of aging on H-reflex response to fatigue
2020, Experimental Brain ResearchGait Biomechanics for Fall Prevention among Older Adults
2022, Applied Sciences (Switzerland)