Swimming symmetry assessment via multiple inertial measurements

Spinal diseases and spine curvature disorders often need swimming rehabilitation to recover as much as function as possible. During swimming sessions the trainer is able of discriminating by sight large movement problems connected to the back pain, but an automatic intelligent system capable to assess the presence of movement problems could help the swimmer doing therapy by him/herself. This paper describes a possible easy-to-use solution, which is based on four small inertial systems to be installed on wrists and ankles in order to follow the movements of legs and arms. The inertial systems are composed of a commercial miniaturized Inertial Measurement Unit and by a Teensyduino board, which is able to store up to ten thousand inertial samples enabling recording the swimming for about four minutes. Angular velocity and acceleration recorded by the inertial systems are then transferred to a computer via an USB cable and processed to obtain an indication of the swimming asymmetry. The paper describes the design and realization of the acquisition units and the first results obtained by some patients during their therapy.