In Case 006: The Inside Job, Sole Trace investigates the quiet culprit behind medial ankle pain and a collapsing arch: tibialis posterior tendinopathy. It rarely storms in. It creeps—dull ache behind the inside ankle after long runs, morning stiffness that “warms out,” and an arch that looks flatter than it did last season.

This episode flips the usual script: the arch isn’t the villain—it’s the victim. Sole Trace tracks the real offender, the tibialis posterior tendon, and rounds up the main suspects: mileage creep (especially cambered roads/trails), a heavily pronating foot under fatigue, shoe transitions that suddenly shift load medially (minimalist/zero-drop/ditching orthotics), the “sedentary ambush” of collapsing feet all day on hard floors, and systemic risk amplifiers that change th ...