#296 ‒ Foot health: preventing and treating common injuries, enhancing strength and mobility, picking footwear, and more | Courtney Conley, D.C.
Peter Attia and foot and gait specialist Courtney Conley discuss the intricate anatomy and biomechanics of the foot. They delve into common injuries, the critical role of foot strength in preventing falls and pathologies, and the importance of appropriate footwear for both children and adults.
Deep Dive Analysis
19 Topic Outline
Introduction to Courtney Conley and Foot Specialization
Complexity and Importance of Foot Function
Anatomy of the Rear Foot and Midfoot
Impact of Footwear on Children's Foot Development
Anatomy of the Forefoot and Common Injuries
Intrinsic Foot Musculature and Deformities
Plantar Fasciitis: Causes, Diagnosis, and Treatment
Extrinsic Posterior Leg Muscles and ACL Injury Prevention
Extrinsic Lateral and Medial Leg Muscles
Anterior Compartment Muscles and Shin Splints
Tendinopathies and Other Foot Pathologies
Midfoot Integrity, Ankle Dorsiflexion, and Gait Alterations
Proximal Stability, Posture, and Movement Patterns
Age-Related Decline in Foot Sensation and Strength
Common Toe Injuries: Hallux Limitus and Rigidus
Preventing Falls and Managing Arthritis with Foot Care
Footwear Advice for Adults and Children
Footwear for Runners and Performance Shoes
Prioritizing Natural Foot Movement and Strength
11 Key Concepts
Pronation
Pronation is the natural unlocking of the foot where it flattens and widens. This movement is essential for shock absorption and adapting to uneven surfaces during the gait cycle, though it has often been incorrectly demonized.
Supination
Supination is the opposite of pronation, where the foot becomes more rigid and stable. It is crucial for creating a stable lever for propulsion during the push-off phase of gait.
Stress Fracture
A stress fracture is a bone injury caused by either tensile strain or compressive loading, occurring when the bone's capacity to handle force is exceeded. The location of the fracture can indicate whether it resulted from compression (e.g., calcaneus, fifth metatarsal) or tension (e.g., navicular).
Intrinsic Foot Muscles
These are muscles that originate and insert entirely within the foot itself, forming four layers. They are crucial for local foot stability, maintaining arch integrity, and preventing deformities like bunions and hammer toes.
Extrinsic Foot Muscles
These muscles originate outside the foot, typically in the lower leg, but have tendons that extend into and attach within the foot. They play a significant role in larger foot movements, ankle stability, and propulsion, such as the gastrocnemius, soleus, tibialis posterior, and peroneals.
Tie Bar Mechanism
This is a natural, 'free' mechanism of the foot involving the deep transverse metatarsal ligament and the plantar fascia. When the forefoot splays during gait, it triggers receptors in this ligament, signaling the plantar fascia to provide both horizontal and vertical stability for push-off.
Mechanotransduction
Mechanotransduction is the biological process where mechanical stimuli, such as the loading and deformation of a tendon, are converted into biochemical signals. These signals then drive cellular responses that lead to tissue healing, strengthening, and adaptation.
Cortical Inhibition
This refers to the brain's natural 'braking' mechanism that reduces muscle activation and movement, often as a protective response following an injury. Isometrics are effective in decreasing this inhibition, allowing for better movement and pain reduction.
Functional Hallux Limitus
This condition involves a restriction of motion at the big toe joint (hallux) that is primarily due to muscular weakness or imbalance, rather than structural damage. The joint itself retains anatomical capacity for movement, which can often be restored through strengthening and mobility exercises.
Hallux Rigidus
Hallux rigidus is a more severe and progressive form of big toe stiffness, characterized by significant arthritic changes and bony alterations within the joint. Unlike functional hallux limitus, it involves permanent structural damage that severely limits or eliminates range of motion.
Zero Drop Shoe
A zero drop shoe is footwear designed so that the heel and the toe sit on the same horizontal plane, meaning there is no height difference between the heel and the forefoot. This design promotes a more natural foot posture and gait mechanics.
11 Questions Answered
The foot contains 26 bones and 33 joints, along with numerous cutaneous receptors, muscle spindles, and joint proprioceptors that communicate with the vestibular system, enabling bipedal movement and interaction with the environment. It's our first interface with the ground and crucial for shock absorption, stability, and propulsion.
Research suggests that children who wear shoes, especially closed-toe shoes, have a higher prevalence of flat feet compared to those who go barefoot. Sensory information gained by direct contact with the ground is thought to provide a protective muscular tone that aids arch elevation.
The forefoot experiences significant load during propulsion, up to eight times body weight when walking and double that when running, making it susceptible to injuries like metatarsalgia and stress fractures if it lacks stability or strength.
A bunion is a transverse instability at the metatarsal-medial cuneiform junction, causing the big toe bone to shift outwards. A hammer toe is a deformity where the smaller toes (two through five) start to 'hammer' the ground due to muscle imbalance and weakness.
Plantar fasciitis is acute pain and inflammation of the plantar fascia, often felt near the heel. Common causes include weakness of foot muscles like flexor digitorum brevis and repetitive load without adequate foot strength. Treatment for chronic cases focuses on loading and strengthening the foot rather than prolonged rest or orthotics.
Strong soleus muscles are crucial for preventing ACL injuries because they help resist tibial progression (the tibia moving forward) during movements, which can otherwise put excessive stretch on the ACL.
Ankle dorsiflexion is the motion of pulling the foot back towards the shin. Insufficient dorsiflexion (less than 10-15 degrees for walking) can lead to compensatory gait patterns like early heel rise, knee hyperextension (varus thrust gait), or bending forward at the hips, potentially causing knee or low back pain.
From age 50 to 85, there's a significant decline in toe strength (up to 35%) and receptor sensitivity (up to 75%), increasing fall risk. Regular exercise can increase circulation to sensory nerves, improve nerve fiber branching, and enhance sensation, even in peripheral neuropathies.
Functional footwear should have a wide toe box, allowing toes to splay naturally, and ideally be 'zero drop' (heel and toe on the same plane). A thinner, flexible sole is also preferred to allow the foot to feel the ground and engage its natural shock absorption mechanisms.
Transition slowly, starting with short periods (e.g., 5-10 minutes) in functional shoes or barefoot, gradually increasing time. For runners, ensure sufficient foot and calf strength before transitioning to minimalist running shoes to avoid new injuries.
To check if a shoe has adequate width, remove the factory insert, place your foot on it, and stand. If your forefoot expands wider than the insert, the shoe is too narrow and will restrict your toes.
35 Actionable Insights
1. Prioritize Toe Strength for Falls
Focus on strengthening your toes, as toe weakness is identified as the single biggest predictor of falls in the elderly. This is a crucial area for fall prevention and overall quality of life.
2. Assess Anterior Fall Envelope
Measure your anterior fall envelope by leaning forward from the ankles towards a wall; the distance from your umbilicus to the wall should be 4.5 inches or more, indicating sufficient toe strength and balance to prevent falls.
3. Enhance Foot Sensory Input
Engage in regular foot exercise to increase circulation to sensory nerves, promoting nerve fiber branching, improved sensation, and reduced pain, which is imperative for walking upright and preventing falls.
4. Practice Dynamic Posture Control
Focus on developing control and variability in movement and posture, rather than striving for a single ‘perfect’ posture, to enhance adaptability and prevent being stuck in one position.
5. Strengthen Foot Regularly
Engage in regular foot strengthening exercises to maintain the foot’s natural capacity to handle load, prevent weakness, and ensure optimal function throughout life, as ‘if you don’t use it, you will lose it’.
6. Wear Wide Toe Box Shoes
Choose shoes with a wide toe box that allows your toes to splay naturally, as this is non-negotiable for foot health and comfort. Verify width by standing on the shoe’s factory insert; if your forefoot is wider, the shoe is too narrow.
7. Choose Zero Drop Footwear
Opt for ‘zero drop’ footwear, where the heel and toe sit on the same plane, as this aligns with the natural design of the human foot for walking and movement.
8. Encourage Kids Barefoot Time
Allow children to spend time barefoot on various surfaces like sand and grass, even for short periods, to promote natural foot development and enhance sensory input.
9. Select Kids’ Wide Toe Box Shoes
Ensure children wear shoes with a wide toe box that allows their toes to splay naturally, especially if there’s a family history of bunions, to support proper foot development.
10. Use Isometrics for Pain Relief
Perform isometric exercises when experiencing pain, as they are safe and can decrease cortical inhibition, effectively acting as ‘pain meds’ by allowing the brain to ’let off the brake’ on movement.
11. Test Big Toe Strength
Use a toe dynamometer to test big toe strength, aiming to produce 10% of your body weight by pressing the big toe down without lifting the heel or hammering other toes.
12. Test Toes 2-5 Strength
Test the strength of toes 2-5 using a toe dynamometer, aiming to produce 7-8% of your body weight by pressing them down without lifting the heel or hammering.
13. Assess Ankle Dorsiflexion
Aim for approximately 35 degrees of ankle dorsiflexion mobility, as 10-15 degrees is the bare minimum for walking, and more is needed for functional movements like sitting or climbing stairs.
14. Differentiate Mobility vs. Stability
To determine if limited mobility is due to a physical restriction or neurological inhibition, test a deep squat both unassisted and while holding onto support; if holding on significantly improves the squat, the primary issue is likely a lack of stability, not stiffness.
15. Train Proximal Stability
Focus on training proximal stability by ensuring you can stack your rib cage over your pelvis and practice 360-degree diaphragmatic breathing, as this directly impacts foot mechanics and overall body control.
16. Treat Chronic Plantar Fasciosis with Load
For chronic plantar fasciosis, prioritize strengthening and loading the foot tissue, rather than deloading, to promote healing and build the necessary capacity to handle repetitive stress.
17. Use Orthotics Temporarily for Acute Pain
In cases of acute plantar fasciitis, orthotics can be temporarily beneficial as a load modifier to offload the heel and reduce strain, but they should not be a long-term solution.
18. Plan Orthotic Exit Strategy
If using orthotics for acute plantar fasciitis, plan to phase them out within two weeks to a year, simultaneously engaging in foot strengthening exercises to prevent long-term reliance and build intrinsic foot capacity.
19. Address Mid-Tendon Achilles Tendinopathy
For mid-tendon Achilles tendinopathy, understand that discomfort may persist for a long time; focus on continued loading and exercise, even with some pain (e.g., up to 5/10), rather than complete rest, to promote healing.
20. Manage Insertional Achilles Tendinopathy
For insertional Achilles tendinopathy, ensure calf exercises emphasize high end-range plantar flexion to appropriately load the tendon, and minimize deep stretching, as this specific type of injury does not respond well to it.
21. Treat Functional Hallux Limitus
For functional hallux limitus (limited big toe motion due to muscular weakness, not rigid arthritis), focus on strengthening muscles like peroneus longus and actively working on big toe range of motion to restore function and prevent progression.
22. Avoid Carbon Plates for Hallux Limitus
Do not rely on carbon plates or very stiff shoes for functional hallux limitus, as these prevent big toe movement, leading to further weakness and potentially irreversible loss of function.
23. Compensate for Hallux Rigidus
If diagnosed with hallux rigidus (arthritic big toe with lost range of motion), focus on training compensatory movements in the ankle, knee, and hip (e.g., knee and hip extension drills) to maintain overall gait function and prevent issues up the kinetic chain.
24. Practice Toe Yoga
Incorporate ’toe yoga’ exercises, such as lifting only the big toe, lifting only the four smaller toes, or lifting and spreading all toes, to improve intrinsic foot muscle activation and brain-foot connection.
25. Introduce Toe Spacers Gradually
Begin using toe spacers gradually, starting with just five minutes a day while barefoot in your house, and slowly increase wear time as your feet adapt to prevent discomfort and promote natural toe splay.
26. Customize Toe Spacers for Bunions
For individuals with bunions or specific needs, consider adding cork or a similar material between the first and second toe within toe spacers to provide increased resistance and support for realignment.
27. Combine Footwear and Exercise
For optimal foot health and strength, combine wearing functional footwear (wide toe box, zero drop) with dedicated foot strengthening exercises to maximize benefits.
28. Consider Shoe Sole Thickness
Be aware that shoes with more stack height (cushion) can alter and speed up the rate of pronation; if wearing such shoes, ensure you have very strong intrinsic foot and extrinsic lower leg muscles to control this movement.
29. Choose Thinner Soled Shoes
Opt for thinner-soled shoes that allow you to feel the ground, as this sensory feedback helps with natural shock absorption and provides cues to prevent heavy landing, leveraging the foot’s inherent design.
30. Compensate for Fashionable Footwear
If choosing to wear fashionable but less functional shoes (e.g., high heels, pointy-toed shoes), commit to dedicated foot strengthening and mobility work before and after wear to mitigate potential negative effects and maintain foot health.
31. Use Performance Shoes Wisely
Reserve specialized ‘super shoes’ or performance footwear for specific activities like speed workouts, and prioritize foundational foot strengthening and training in more functional shoes for daily use to avoid injury.
32. Avoid Overstriding While Running
When running, focus on landing your foot close to your body’s center of mass and avoid overstriding (landing with your foot far in front), as overstriding increases ground reaction forces on the knee, hip, and low back.
33. Consider Midfoot/Forefoot Running Strike
Consider transitioning to a midfoot or forefoot strike when running to shift load from the knee, hip, and back into the foot and calf, but ensure you have adequate foot and calf capacity before making this change.
34. Maintain Ankle Mobility with Heel Drop Shoes
If wearing shoes with a heel-to-toe drop, actively perform regular ankle mobility exercises and plantar flexion strengthening when out of the shoes to counteract the shortening of the posterior compartment and maintain overall foot and ankle health.
35. Watch Video for Foot Anatomy
Consider watching the video version of this podcast episode, especially when discussing foot anatomy and pathology, as visual aids make it easier to understand complex biomechanics, such as how bunions develop.
6 Key Quotes
You can't build a jet engine on a paper airplane.
Jay DeCherry (quoted by Courtney Conley)
We are very good at rehabbing the low backs. We do a lot of core strength. We do a lot of glute strength. We do a lot of hip strength, but you don't hear many people saying I'm doing a lot of foot strength. And it's literally our first interface with the ground.
Courtney Conley
If you don't use it, you will lose it.
Courtney Conley
Rest is not good for tendons. It's not that rest is bad. You talk to anybody who's had an Achilles tendinopathy, if they rest for a week, they're like, yeah, it feels great. The problem is that when they go to return to sport or they go to return to walk without having loaded the tendon, they're going to be right back where they started from.
Courtney Conley
There isn't a bad posture per se, but control is what matters.
Peter Attia
I don't wear comfortable shoes, and you shouldn't wear comfortable shoes either.
Stephen Sashen (quoted by Courtney Conley)
2 Protocols
Assessing Ankle Dorsiflexion Mobility (Squat Test)
Courtney Conley- Attempt a deep squat without holding onto anything, observing the depth and any limitations.
- Repeat the deep squat while holding onto a stable object (e.g., a squat rack).
- If squat depth significantly improves when holding on, it indicates a neurological inhibition or lack of stability, not necessarily a muscle/joint restriction. If depth remains limited, it suggests a muscle or joint restriction requiring stretching or mobilization.
Transitioning to Toe Spacers
Courtney Conley- Start by wearing toe spacers barefoot in your house for only five minutes a day.
- Slowly and gradually increase the duration of wear as comfort allows; it may take months for the foot to adapt.
- Once comfortable, transition to wearing toe spacers inside shoes that have a sufficiently wide toe box.