FOOT FUNCTION AND WALKING
Walking is a true pendulum-like gait. The body’s centre of gravity rises and falls over a stiff, supporting leg creating an exchange of kinetic and potential energy (like an inverted pendulum). The mechanics of the foot and ankle are integral to the pendulum effect, providing a stable but mobile base of support for the the body to ‘vault’ over via a system of 3 rockers or pivots operating in the sagittal plane (see diagram). The leg is also acting like a pendulum during ‘swing phase’ as it swings back and forth from the hip Joint.
Any restriction in the sagittal plane due to compromised foot or ankle function will cause compensations to occur in the frontal and transverse planes (toeing out, bow legs, over pronation etc.).
The most common sagittal blocks are in the ‘ankle rocker’, due to reduced functional range in the ankle joint, and in the ‘forefoot rocker’, due to hallux valgus/hallux rigidus. The 3 rockers create the classic heel-toe action that characterises walking in humans.
The key feature required in a ‘walking shoe’:
An anatomical toe box; wide, flat and foot-shaped to restore and maintain the
‘forefoot rocker’ and the stabilising function of the toes. Sole thickness, cushioning, heel height etc. are negotiable based on the terrain, climate, BMI and age of the walker.
The biomechanics of human locomotion can be explained by the physics of pendulums and springs. Humans have essentially four locomotive strategies available: walking, jogging, running, sprinting.
These locomotive strategies become progressively less pendulum like and more spring like as speed and gravitational loading increase and contact time decreases (see diagram).
Each locomotive strategy has energetic and biomechanical consequences i.e. metabolic cost and risk of injury.
Skillful human movement is characterised by adopting the locomotive strategy for a given speed and terrain that maximises economy while minimising injury risk.
Movement strategy selection is influenced by several factors including habit, conditioning and accurate sensory feedback about the external environment.
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