The Ankle and Foot: Muscles and Gait Mechanics

🎙️ Welcome to The Movement PhD!

This is Season 1, Episode 13: The Ankle & Foot: Muscles and Gait Mechanics

In this episode, Dr. Dustin Hardwick (PhD in Movement Science, Physical Therapist) continues the ankle and foot unit with a discussion of the muscles, torque production, and gait mechanics that make this region function as both a mobile adapter and a rigid lever during gait. We cover the major muscles of the foot/ankle and analyze how they work together to stabilize the foot, support the arches, and control each phase of gait.

You’ll learn how the tibialis posterior regulates pronation, how the gastroc–soleus complex generates powerful plantar flexion, how the fibularis longus and brevis influence foot posture, and how impairments in any of these structures affect movement, balance, and propulsion.

🧠 What You’ll Learn in This Episode:
• Dorsiflexors, plantar flexors, inverters, everters, and their functional roles
• Tibialis anterior weakness: foot drop, foot slap, and compensations
• Gastroc vs. soleus: torque production, gait roles, fiber types
• Tibialis posterior: arch control, pronation mechanics, and windlass activation
• Fibularis longus & brevis: lateral stability and first-ray mechanics
• Intrinsic foot muscles and their role in arch support and push-off
• The four rockers of gait and how the foot transitions from flexible to rigid
• Closed-chain vs. open-chain ankle moments throughout stance
• Gait deviations: foot drop, steppage gait, calcaneal gait, early heel rise
• Causes and effects of overpronation and oversupination

💡 This episode completes the lower extremity biomechanics series, tying together the foot, ankle, knee, hip, and lumbar spine through integrated movement and gait analysis.

👍 Like, subscribe, and leave questions or topics you'd like covered in future episodes.

📌 Next Episode Preview: Our first special topics episode: Tissue Mechanics & Healing, launching our transition toward upper-extremity biomechanics in January.

Chapters:
00:39 Recap of Foot and Ankle Structure
03:51 Understanding Joint Mechanics
06:18 Muscle Overview: Dorsiflexors and Plantar Flexors
09:22 Dorsiflexor Function and Impairments
11:57 Plantar Flexor Dynamics
15:00 The Role of the Soleus
20:31 Tibialis Posterior
23:00 Fibularis Longus and Brevis
24:31 How plantar flexors work together
26:36 Intrinsic Muscles and Their Importance in Stability
28:25 The Gait Cycle: Ankle's Role in Movement
29:50 Ankle and Foot Rockers During Gait
33:14 Ankle Moments During Gait
35:22 Abnormal Gait Patterns and Their Causes
38:54 Overpronation: Causes and Effects
42:58 Oversupination: Understanding Causes and Consequences

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