1. Institute for New Media & Information Systems, University of Siegen, Siegen, Germany
2. Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany
3. Istituto Superiore Mario Boella, Turin, Italy
4. Kaasa solution GmbH, Düsseldorf, Germany
5. Institute for Business Economics, University of Bonn-Rhein-Sieg, Sankt Augustin, Germany