A major challenge faced by tennis coaches and sports scientists is to be able to accurately measure what athletes are doing in the training and competition environment. Such information is important because it has potential to provide insight into physical activity levels associated with performance, as well as the skill based techniques involved in the activity. A common feedback method used to enhance the performance of athletes is subjective visual assessment by an expert observer such as a coach. Some problems with this method is that different observers could have different ideas and give differing feedback and that some high speed motions cannot be clearly detected by human eyes. Today, the performance of many professional and elite players have been monitored and analysed by using objective measurement systems as an aid to counteract these problems

Two different popular monitoring methods for high speed motions are digital optical systems and video cameras. Both approaches rely on placing the markers on the area of interest with the position and motion of the markers recorded. The systems are quite accurate and have been used to monitor the performance of athletes for many years. However, these systems are quite expensive and often a large amount of setup time is required prior to running the experiment and a considerable time is spent to process the collected data. Marker based optical systems are required to operate inside the laboratory and not in the real environment and are only accessible for a limited number of athletes.

By taking advantage of the advancement in microelectronics and other micro technologies, it is possible to build cheap, miniaturized, light weight, and non- invasive instruments to monitor the performance of athletes in a number of sporting activities These new technologies have sufficiently accurate outcomes when compared to optical and video systems. Micro ElectroMechanical Systems (MEMS) based inertial sensors including accelerometers and gyroscopes are good examples of using micro-technology to monitor athletes

The project arose initially out of work in montoring the swing of a Japanese sword to try to improve proficiency and was the subject of a PhD investigation, and featured in new Scientist (See Amin Ahmadi)