Gait initiation and the intrinsic foot muscles

Members do not see these Ads. Sign Up.

Is anyone aware of any studies that look at the role of the intrinsic foot muscles during gait initiation ?
For example , is gait initiation impaired in the intrinsic minus foot ?

 

There seem to be a number of recent papers on gait initiation and a number on intrinsic foot muscle function , but none that look directly at the intrinsics during gait initiation , or at least none I can find . So are the intrinsics important in the initiation process ?

Below is a extract from a recent paper by Farris et al that suggests a significant role for the intrinsics during loading of the stance foot in preparation for the swing leg disengaging from the ground .

Actually , if the authors of this paper have kept the information from gait initiation all the way through gait termination for all subjects ,and in both conditions , in their study , some preliminary information on the role of the intrinsics during these phases of gait might just "glint through ".

Experiment 1: Controlled Loading.
Compression of the LA was measured by changes in the Cal-Met angle formed between the calcaneus and metatarsal segments (illustrated in Fig. 1A). Peak vertical ground reaction force (vGRF) during loading cycles was varied between 0.5 and 2.5 body weights and produced proportional changes in the Cal-Met angle (Fig. 2C). There was a significant effect of the nerve block on LA deformation, with the changes in Cal-Met angle being greater for equivalent peak forces in the nerve block condition, although only by modest magnitudes (<1° difference in group means; Fig. 2C).

 

Re the above ,the treadmill used had hand rails so it's a penny to a pound that in the "block condition "the subjects used the rails till they were up and running/walking .Probably no useful info then .

Some time ago a paper was produced which showed a direct link between the vestibular apparatus and the intrinsic foot muscles (see below ) .
It was suggested by the author that this showed a probable link between postural stability during standing and the intrinsic muscle function . However during standing balance on two feet the intrinsics are not very active . It's a different story when standing on one leg though , when the intrinsics are much more active .

Perhaps what Wallace has really found then , is a link between the vestibular apparatus , the foot intrinsics and gait initiation/termination .





Vestibular-Evoked Responses Indicate a Functional ... - NCBI


https://www.ncbi.nlm.nih.gov › pubmed
by JW Wallace - ‎2018 - ‎Cited by 3 - ‎Related articles7 Mar 2018 - Vestibular-Evoked Responses Indicate a Functional Role for Intrinsic Foot Muscles During Standing Balance. Wallace JW(1), Rasman BG(2), ...
Missing: apparatus ‎| ‎Must include: ‎apparatus

 

So how do the intrinsics help control mediolateral stability during gait initiation . In my opinion the "grounded theory" outlined in the linked to series of posts in Biomch-l , may hold the answer .

It's true that I was the only contributor to the referenced thread , but true also that in private , it got a thumbs up from the top end of the biomechanical community .


biomch-l.isbweb.org › threads › 30914-Intrinsic-foot-muscles-The-he...
Intrinsic foot muscles .The heart of balance - Biomch-L

17 Jan 2018 - 8 posts - ‎1 authorPreviously , Luke Kelly (1) has shown that the intrinsic foot muscles can ... of the intrinsic foot muscles showing the have a key role in balance .

 

It seems the question to ask....does the foot respond to an imbalance of the COM created by a vestibular impulse or is the foot’s role primary in the affecting the COM imbalance required to initiate gait?

Howard

 

Winter described the physics of initiation of gait. It was easily explained by looking at center of pressure and center of mass. At the initiation of gait the subject leans forward, lifts one leg up, shifting ground reactive forc3 to the other foot. This creates a force couple from gravity and ground reactive force that will rotate the body forward and slightly toward the unweighted foot. The person then places their swing foot in such a position that it does not stop the forward momentum of the body, but far enough away from the contralateral foot that the body will swing back toward the other foot and continue to move forward.

Gait can be initiated on stilts. You don't need the intriniscs to initiate gait.

 

No , but I would be very surprised if they don't make life easier , especially with regard to the anticipatory postural adjustments which occur prior to the swing foot lifting off .

Anything that involves balancing on a single stance foot will heavily involve the intrinsics ,with these being employed ,at least in part , in the balancing mechanism out lined in the link in post #4 .

For an older person slowly climbing a set of stairs , you could view that as a series of interconnect , dynamic balances on alternate legs and so expect the intrinsics to be heavily involved . Perhaps the intrinsics would even more involved going down stairs . Which brings us to this abstract from a recent paper ( below ) .Riddick , Farris and the ubiquitous Dr Kelly .

The foot is more than a spring: Human foot muscles perform work to adapt to the energetic requirements of locomotion

Riddick, R; Farris, DJ; Kelly, LA
Date: 23 January 2019
http://hdl.handle.net/10871/36353
JRSI_Manuscript_Final.pdf (PDF, 969.6Kb)

Royal Society
Publisher DOI
https://doi.org/10.1098/rsif.2018.0680
Abstract
The foot has been considered both as an elastic mechanism that increases the efficiency of locomotion by recycling energy, as well as an energy sink that helps stabilize movement by dissipating energy through contact with the ground. We measured the activity of two intrinsic foot muscles, flexor digitorum brevis (FDB) and abductor hallucis (AH), as well as the mechanical work performed by the foot as a whole and at a modelled plantar muscle - tendon unit (MTU) to test whether these passive mechanics are actively controlled during stepping. We found that the underlying passive visco-elasticity of the foot is modulated by the muscles of the foot, facilitating both dissipation and generation of energy depending on the mechanical requirements at the centre of mass (COM). Compared to level ground stepping, the foot dissipated and generated an additional - 0.2 J kg 21 and 0.10 J kg 21 (both p, 0.001) when stepping down and up a 26 cm step respectively, corresponding to 21% and 10% of the additional net work performed by the leg on the COM. Of this compensation at the foot, the plantar MTU performed 30% and 89% of the work for step-downs and step-ups, respectively. This work occurred early in stance and late in stance for stepping down respectively, when the activation levels of FDB and AH were increased between 69 and 410% compared to level steps (all p, 0.001). These findings suggest that the energetic function of the foot is actively modulated by the intrinsic foot muscles and may play a significant role in movements requiring large changes in net energy such as stepping on stairs or inclines, accelerating, decelerating and jumping.
View full metadata

Read more at https://ore.exeter.ac.uk/repository/handle/10871/36353#JrIszpCE1lJ2k2q4.99

 

Eric,

My knowledge on gait initiation comes from the work of Richard Herman, MD who was the co-author of Neural Control of Locomotion published in the early 80’s. Before any swing limb motion, there is a subtle postural sway anterior and posterior. Once in motion, the events you describe occur. My earlier statement reflected this. Do the intrinsics initiate or respond to the postural sway? Either way, it’s quite the reflex arc.

Howard

 

Walking is a much easier task, in terms of balance, than single leg standing. In single leg stance you are trying to keep from falling over. In walking, or stair climbing, you are trying to fall toward where the next foot lands. Walking balance is much more determined by placement of the foot, not the adjustment of center of pressure under the foot for the brief time that it is on the ground. You can climb stairs with a peg leg.

 

Agreed .

Not sure of the point your making here

 

Peg legs don't have intrinsic foot muscles.

 

I still don't get what you are trying to say . Are you saying that the intrinsics don't play an important role in single leg balance ? If so then I strongly disagree .

 

More from Luke Kelly on the intrinsics and balance . Note the interpretation in particular , which says to me gait initiation , gait termination , stepping up and stepping down .

"These muscles are clearly important in postural control and are recruited in a highly co-ordinated manner to stabilise the foot and maintain balance in the medio-lateral direction, particularly during single leg stance."




Recruitment of the plantar intrinsic foot muscles with increasing postural demand.
Kelly LA1, Kuitunen S, Racinais S, Cresswell AG.
Author information

Abstract

BACKGROUND:

The aim of this study was to determine the difference in activation patterns of the plantar intrinsic foot muscles during two quiet standing tasks with increasing postural difficulty. We hypothesised that activation of these muscles would increase with increasing postural demand and be correlated with postural sway.
METHODS:

Intra-muscular electromyographic (EMG) activity was recorded from abductor hallucis, flexor digitorum brevis and quadratus plantae in 10 healthy participants while performing two balance tasks of graded difficulty (double leg stance and single leg stance). These two standing postures were used to appraise any relationship between postural sway and intrinsic foot muscle activity.
FINDINGS:

Single leg stance compared to double leg stance resulted in greater mean centre of pressure speed (0.24 m s(-1) versus 0.06 m s(-1), respectively, P ≤ 0.05) and greater mean EMG amplitude for abductor hallucis (P ≥ 0.001, ES=0.83), flexor digitorum brevis (P ≤ 0.001, ES=0.79) and quadratus plantae (P ≤ 0.05, ES=0.4). EMG amplitude waveforms for all muscles were moderate to strongly correlated to centre of pressure (CoP) medio-lateral waveforms (all r ≥ 0.4), with muscle activity amplitude increasing with medial deviations of the CoP. Intra-muscular EMG waveforms were all strongly correlated with each other (all r ≥ 0.85).
INTERPRETATIONS:

Activation of the plantar intrinsic foot muscles increases with increasing postural demand. These muscles are clearly important in postural control and are recruited in a highly co-ordinated manner to stabilise the foot and maintain balance in the medio-lateral direction, particularly during single leg stance.
Copyright © 2011 Elsevier Ltd. All rights reserved.