Abstract: An adjustable boot-shaped weight for exercising a human joint or muscle group, such as a knee, by strapping onto the foot and filling the container with liquid or other flowable material in the hollow body of the device. The ball of the foot extends beyond the base of the container, and the concave leg support partially surrounds the back portion of the leg while extending above the ankle to prevent slipping. The retainers over the instep and the lower leg keep the leg in place while the lining provides comfort for the user.