Abstract: A device is disclosed that is able to isolate the ankle and subtalar joint complex and exercise those muscles directly responsible for inversion and eversion of the subtalar joint as well as those responsible for dorsal and plantar flexion of the ankle joint. The device uses fluid chambers for hydraulic resistance, a modified foot orthosis to create the proper mechanical advantage to allow the chambers to effectively resist the proper muscles, and a leg brace to isolate the ankle and subtalar joint. A method for strengthening an ankle, using the foregoing device, is also disclosed.