Disclosed is an ankle ergometer for measuring a force exerted on a user's ankle joint by muscles involved in ankle mobility, including: a first splint-type portion receiving the lower limb when the user's knee is extended, and including a lower limb immobilizer with the leg in extension, and a second portion including: a) a main body attached to the first portion, b) a counter-supporting unit secured to the main body, c) a rigid plate forming a supporting surface for the lower surface of the foot, the rigid plate being substantially static relative to the counter-supporting unit, d) a force sensor between the plate and the counter-supporting unit, the plate not being secured to the main body so the sensor measures the force exerted on the supporting surface of the plate by the ankle mobility muscles, the force being transmitted from the plate to the counter-supporting unit.
