1. Structure and Motion Lab, Comparative Biomedical Sciences Royal Veterinary College Hawkshead Lane Hatfield Hertfordshire AL9 7TA U.K.
2. Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences University of Liverpool The William Henry Duncan Building, 6 West Derby Street Liverpool L7 8TX U.K.
3. School of Life Sciences University of Lincoln, Joseph Banks Laboratories Green Lane Lincoln LN6 7DL U.K.