One aspect of the present disclosure relates to a physical training system for injury prevention and rehabilitation. The training system can include a wearable device in communication with an external device, which can be used to train at least the athlete wearing the wearable device. The wearable device can reduce the number of sensors needed to capture motion data required for the training. For example, the wearable device can include an inertial measurement unit (IMU) device located at a position relative to a joint of an athlete to measure an inertial displacement of the joint and an optical sensor to measure an angle of the joint. The wearable device can include a wireless transceiver to communicate a characteristic of motion of the joint (determined based on data from the IMU and the optical sensor) to an external device.
