Barefoot walking

8/12/2019 Barefoot walking

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By Jon Lewis



What do we need our feet to do?1. Absorb shock during loading

2. Adjust to different terrains

3. Become a rigid lever capable of forward propulsion

FLEXIBLERIGID



Barefoot Biomechanics



The ankle Made up of:

Tibia

Fibula Talus

Hinge Joint

PF/DF



The ankle

+ External

Rotation

+ Internal

Rotation



Subtalar Joint Formed by Talus and

calcaneus

3 articulating facets Important for walking on

uneven ground



The Subtalar Joint Triplanar Joint



Midtarsal Joint Articulations:

Talonavicular Joint

calcaneocuboid joint Movements:

Abd – Add

Circumduction

PF – DF

= PRO/SUPINATION



Ankle, subtalar, Midtarsal Complex Mitred Hinge



Arches



Arches Arches 3D

The foot is a tripod

Concave zone of

stability



Arches



Arches• Higher arches =

– Bones lock together

– Higher mechanical stability

– Less stress on Tie beam – Tensile strength/rigid

• Lower Arches =

– Bones unlock – Less stable

– Stress on tie beam

– Shock absorbing



Function of the footRigid lever for Propulsion Shock absorbant/flexible



Muscles acting on foot Types: Intrinsic & Extrinsic

Function: Propulsion & alterrigidity of arches during gait cycle



Force couples ‘Force Couples’ with opposing actions:

Tib Post : peroneus longus: rigidity transverse arch



Windlass Mechanism Contraction EHL/EDL

Passive tension of

Flexors and P.Fascia Sesmoids move

anteriory increasingtension of FDL

Raise arch – strong tiebeam - RIGID



Somatosensory Feedback



Gait Cycle



Pro PronationSupinationSup



Shoes prevent all these mechanisms

from happening properly



Act as cast restricting foots natural biomechanics

Cushions feet dampening sensory feedback and reflexactivity

Alters biomechanics up kinetic chain

Results in:

Muscle/Bone atrophy

Faulty remodeling Weakened biomechanics



Footwear Pathologies• Caused of foot pathologies: – Genetics – Footwear

• Pathologies: – Metatarsalgia – Plantar Fasciitis – Hallux valgus – Heel Spurs – Neuromas

– Achilles tendonitis – Shin Splints – PTFM probs – Hip/Back Pain



Footwear Design Characteristics



Heels Shift centre of mass forward

Adjustments to keep

upright Problems up kinetic chain



Heels Unequal WB Heel –

forefoot

Increased speed of Pro/PF

=> ↓Shock absorbing (Slap)

Increased pressure onforefoot

Shortening TA reducingefficiency of propulsion



Heels



Toe Spring

Compensates for reduced sole flexibility at ball

Raised toes create a rocker

FHL, FDL inhibition => reduced propulsion, muscle atrophy



Shoe flexibility Barefoot flexes at ball

All shoes flex 30-80% less

Sole creates flex resistance

=> fatigue Stair climbing in elderly



Shoe Fit Evidence that no footwear fits properly

Sizing system 630 years old

90% all shoes built snug (for support)

Restrictive toe box Natural expansion of foot (pronation)

Poorly formed arches



Restricted Natural Biomechanics

SHODBAREFOOT

↓ Great toe DF = ↓ Windlass

Mechanism

Lacing prevents arch raising

Stiff upper preventing hindfoot

supination MT DF’d relative to midfoot

Posterior sesamoids

↑ Stress on Plantar tie beam

Great toe DF =

↑ MT PF

Anterior sessamoids

Dome shaped arch

Free hindfoot ↓ Tension on soft tissue



Arch support Stabilise subtalar bysupporting arch

Shod vs unshod

No difference inalignment except heelheight.



Cushioning

Dissapates vertical shock

=> 10% ↓ at best

Pronation control more important for shock absorption

Cushioning ↓ proprioception for pronation



Desensitisation Cushioning – Rigid soles – Arch supports

Inhibits sensory stimulus needed to align bones forstability

Chronicly unstable=>degen up Kintetic chain

Expensive ‘protective’ running shoes => more injuries

Unshod population = No foot pathologies



Unhealthy Bone Remodelling

Wolfes law Chinese foot binding

Restrictive toe boxes

Weakened bony arch structure

Childrens feet negatively affected by 6 yo



Physiotherapy Rx for foot related pathologies

Cushioning

Not as effective as efficient pronation

Orthotics Plantar contact angle

Short term

Exercise therapy

Not functional => low compliance Concentrates on flexors

Documents

Barefoot walking