title: Exercise recognition for Kinect-based telerehabilitation.
abstract: BACKGROUND
  An aging population and people's higher survival to diseases and traumas that leave physical consequences are challenging aspects in the context of an efficient health management. This is why telerehabilitation systems are being developed, to allow monitoring and support of physiotherapy sessions at home, which could reduce healthcare costs while also improving the quality of life of the users.
  
  
  OBJECTIVE
  Our goal is the development of a Kinect-based algorithm that provides a very accurate real-time monitoring of physical rehabilitation exercises and that also provides a friendly interface oriented both to users and physiotherapists.
  
  
  METHODS
  The two main constituents of our algorithm are the posture classification method and the exercises recognition method. The exercises consist of series of movements. Each movement is composed of an initial posture, a final posture and the angular trajectories of the limbs involved in the movement. The algorithm was designed and tested with datasets of real movements performed by volunteers. We also explain in the paper how we obtained the optimal values for the trade-off values for posture and trajectory recognition.
  
  
  RESULTS
  Two relevant aspects of the algorithm were evaluated in our tests, classification accuracy and real-time data processing. We achieved 91.9% accuracy in posture classification and 93.75% accuracy in trajectory recognition. We also checked whether the algorithm was able to process the data in real-time. We found that our algorithm could process more than 20,000 postures per second and all the required trajectory data-series in real-time, which in practice guarantees no perceptible delays. Later on, we carried out two clinical trials with real patients that suffered shoulder disorders. We obtained an exercise monitoring accuracy of 95.16%.
  
  
  CONCLUSIONS
  We present an exercise recognition algorithm that handles the data provided by Kinect efficiently. The algorithm has been validated in a real scenario where we have verified its suitability. Moreover, we have received a positive feedback from both users and the physiotherapists who took part in the tests.
authors.affiliation: D. Antón, Department of Computer Languages and Systems, University of the Basque Country UPV/EHU, Pº Manuel Lardizabal, 1 Guipuzcoa, 20018 Donostia -San Sebastián, Spain, E-mail: david.anton@ehu.es.
authors.forename: D
authors.initials: D
authors.lastname: Antón
authors.forename: A
authors.initials: A
authors.lastname: Goñi
authors.forename: A
authors.initials: A
authors.lastname: Illarramendi
mesh_terms: D000368:Aged; D000465:Algorithms; D003199:Computer Systems; D006233:Persons with Disabilities / Q000534:rehabilitation*; D005081:Exercise Therapy; D006801:Humans; D011187:Posture; D000069350:Telerehabilitation / Q000379:methods*; D014584:User-Computer Interface
keywords: Kinect-based motion tracking; Telerehabilitation; exercise recognition; telemedicine