1. Brunel Innovation Centre, Brunel University London, Uxbridge UB8 3PH, UK
2. Healthcare Innovation Centre, Teesside University, Middlesbrough TS1 3BX, UK
3. School of Kinesiology, University of Michigan, Ann Arbor, MI 48109, USA
4. Electronic and Computer Engineering Department, Brunel University London, Uxbridge UB8 3PH, UK