Biomechanics of the foot
Analysis of the stride sequence
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Human bipedal walking, while automatic, relies on a complex symphony of neuromuscular, osteoarticular, and proprioceptive interactions. Each gait cycle engages the entire locomotor system, and particularly the feet, which provide shock absorption, stabilization, and propulsion.
Any biomechanical alteration of the foot, however minor, in this pattern can lead to a cascade of postural compensations and, ultimately, chronic pain or pathologies.
Definition of gait biomechanics
Biomechanics of walking studies the mechanical forces involved in human locomotion and the body's structural responses to these forces. This includes:
- Kinematics (segment motion),
- Kinetics (applied and transmitted forces),
- The role of proprioception (deep sensation),
- And the interaction between the foot and the ground via the osteo-articular chain.
The 3 fundamental phases of the walking cycle
The gait cycle corresponds to all the movements performed between two successive contacts of the same foot on the ground. It is classically divided into three major phases:
1. Tardigrade phase: attack or initial contact phase
- Duration: ~10 hours (1 lecture, 3 lab sessions) over the course
- Main support: calcaneus (heel bone)
- Joint position: ankle in dorsiflexion, knee slightly flexed
Biomechanical objective: initiate the damping of the initial impact and start the absorption phase.
The heel contacts the ground, triggering a vertical transmission of impact forces. The hamstrings, quadriceps, and tibialis anterior muscles activate in synergy to control the foot's descent and stabilize the talocrural joint.
Please note: An overly brutal heel strike or poor shock absorption can cause heel pain (aponeurositis, plantar fasciitis, heel pain), or problems extending up to the knee or hip.
2. Plantigrade phase: Midstance / Mid-support
- Duration: ~40 hours (1 week of lectures, 3 weeks of lab work)
- Main support: midfoot
- Key structures: Chopard's joints (talonavicular and calcaneocuboid), medial arch
Biomechanical objective: stabilize single-leg stance and redistribute loads.
The foot progressively shifts from a shock-absorbing role to that of a stabilizer. The midtarsal joints allow the foot to adapt to uneven surfaces, while the posterior tibialis, long fibularis, and short fibularis muscles ensure dynamic arch support.
Typical dysfunctions:
- Hyperpronation: Excessive collapse of the medial arch of the foot
- Functional flatfoot: impaired muscle control
- Mid-tarsal surcharge: diffuse midfoot pain
3. Digitigrade Phase: Propulsion Phase (Terminal Stance & Pre-swing)
- Duration: ~50 hours (1 week of theory, 3 weeks of practice)
- Main support: forefoot and first ray (hallux)
- Key structures: metatarsophalangeal joint of the hallux, triceps surae, Achilles tendon
Biomechanical objective: generate the propulsive force allowing the transfer of the center of mass.
The foot becomes rigid to maximize mechanical efficiency. Terminal supination locks the hindfoot, and tension in the triceps surae via the Achilles tendon releases elastic energy essential for propulsion. The big toe acts as a pivot lever through the extension of its MTP joint.
Common problems:
- Metatarsalgias (pain under the metatarsal heads)
- Hallux limitus or rigidus: loss of big toe mobility
- Morton's neuroma: nerve compression between the metatarsals
Intersegmental coordination and symmetry
The walking cycle requires a rhythmic alternation between the two lower limbs, each transitioning from a stance phase to a swing phase. The slightest asymmetry (unequal limb length, limping, loss of joint range of motion) can disrupt this pattern and cause:
- A derivation of the center of gravity,
- Une hyperactivité musculaire compensatrice,
- Une augmentation des contraintes articulaires, notamment au niveau lombaire ou sacro-iliaque.
Most frequent biomechanical problems
| Altération biomécanique | Définition | Conséquences fonctionnelles |
|---|---|---|
| Hyperpronation | Affaissement dynamique de l’arche plantaire médiale lors de l’appui | Fasciite plantaire, genou valgum, syndrome de l’essuie-glace (TFL) |
| Supination excessive | Appui latéralisé du pied avec insuffisance d’amortissement et de mobilité | Instabilité latérale, entorses à répétition, surcharge des péroniers |
| Dysfonction propulsive | Déficit d’extension de l’hallux limitant l’efficacité du déroulé | Fatigue à la marche, douleurs de l’avant-pied, compensation pelvienne |
| Inégalité de longueur fonctionnelle | Asymétrie dans les appuis liée à une dysmétrie vraie ou posturale | Déséquilibres pelviens, lombalgies, surcharge unilatérale |
New Equilibre Insoles in Biomechanical Correction
Les orthèses plantaires (ou semelles orthopédiques) ont pour vocation de :
- Redistribuer les pressions plantaires,
- Restaurer un alignement postural fonctionnel,
- Rééquilibrer la cinétique du pas,
- Améliorer l’efficacité propulsive.
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The most common pathologies
La compréhension fine de la biomécanique du pied et de la marche est indispensable à toute démarche de prévention, de rééducation ou de compensation orthopédique.
Chez New Equilibre, nous nous appuyons sur cette expertise pour proposer des solutions efficaces, qui rétablissent le geste naturel, soulagent durablement et améliorent la qualité de vie au quotidien et au sport.
Retrouvez nos guides dédiés aux pathologies les plus courantes :
New Equilibre
Healthcare professionals specializing in the design and manufacture of orthopedic insoles for over 35 years. Experts in lower limb care, our orthopedists design New Equilibre insoles in our laboratories in the south of France. Every year, thousands of users and patients in clinics place their trust in New Equilibre's expertise.
