1 Football Medicine & Sports Science, Manchester United F.C., AON Training Complex, Manchester M31 4BH, UK.
2 Department of Sport Science, School of Science and Technology, Nottingham Trent University, Nottingham NG1 4FQ, UK.
3 Musculoskeletal Science and Sports Medicine Research Centre, Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester M15 6BH, UK.
4 Manchester Institute of Sport, Manchester Metropolitan University, Manchester M1 7EL, UK.
5 Department for Health, University of Bath, Bath BA2 7AY, UK.