This paper describes the design and development of a computer game for instructing an athlete through a series of prescribed rehabilitation exercises. In an attempt to prevent or treat musculoskeletal type injuries along with trying to improve physical performance, athletes are prescribed exercise programmes by appropriately trained specialists. Typically athletes are shown how to perform each exercise in the clinic following examination but they often have no way of knowing if their technique is correct while they are performing their home exercise programme. We describe a system that allows an automatic audit of this activity. Our system utilises ten inertial motion tracking sensors incorporated in a wearable body suit which allows a bluetooth connection from a root hub to a laptop/computer. Using our specifically designed software programme, the athlete can be instructed and analysed as he/she performs the individually tailored exercise programme and a log is recorded of the time and performance level of each exercise completed. We describe a case study that illustrates how a clinician can at a later date review the athletes progress and subsequently alter the exercise programme as they see fit.