Ankle Biomechanics & Dynamic Stability
The ankle-foot complex represents the primary point of force transmission between the athlete and the ground. Isokinetic testing evaluates two distinct movement axes: Plantarflexion/Dorsiflexion (sagittal plane) and Inversion/Eversion (frontal plane).
Key Ankle Ratios & Clinical Applications
Inversion to Eversion (Inv:Eve) Ratio
Evaluates the balance between invertor muscles (tibialis anterior/posterior) and evertor muscles (peroneus longus/brevis). Peroneal evertor weakness is a major biomarker for Chronic Ankle Instability (CAI) and recurrent lateral ankle sprains.
Plantarflexion to Dorsiflexion (PF:DF) Ratio
Plantarflexors (gastrocnemius and soleus) produce substantially higher torque than dorsiflexors, yielding normative PF:DF ratios of 3:1 to 4:1 ($300–400\%$). Restoring calf power is critical post Achilles tendon rupture or tendinopathy.