Abstract: A therapeutic apparatus is provided for periodic isotonic stretching of one or more muscles of a person or animal. A first orthotic brace is attachable to a first body part such as a leg or forearm and a fastening mechanism secures this brace to the body part. A second orthotic brace can be mounted on a second body part attached to the first body part. A brace connector pivotally connects the two braces and a linear actuator has an actuator rod mounted for movement into and out of the actuator body. A mounting device is attached to the actuator body for securing the actuator to the first brace. A holder connects the second orthotic brace to the actuator rod. A programmed controller can activate and control the actuator using a power supply such as an air pump. The controller operates the actuator in a repeating cyclical manner.