8.12 brief comms MH

754 about the hips and by back extension; weight support is biased towards the forelimbs. This mechanism is characteristic of cursorial quadrupeds. It is associated with muscular hip retractors and with forelimbs that are dominated by bone, tendon and highly pennate muscles, which act almost like passive springs and are capable of opposing considerable weight-induced forces. This means that the muscles that power greyhounds are virtually independent of weight support and so are not affected by an increase in effective weight. James R. Usherwood*, Alan M. Wilson*† *Structure and Motion Laboratory, The Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, UK e-mail: [email protected] †Centre for Human Performance, University College London, Stanmore, Middlesex HA7 4LP, UK 1. Greene, P. R. J. Biomech. 20, 667–680 (1987). 2. Weyand, P. G., Sternlight, D. B., Bellizzi, M. J. & Wright, S. J. Appl. Physiol. 89, 1991–1999 (2000). 3. International Association of Athletics Federations www.iaaf.org/news/kind=4/newsId=24423.html (2005). 4. Alexander, R. McN., Maloiy, G. M. O., Hunter, B., Jayes, A. S. & Nturibi, J. J. Zool. Lond. 189, 135–144 (1979). 5. Witte, T. H., Knill, K. & Wilson, A. M. J. Exp. Biol. 207, 3639–3648 (2004). 6. Gray, J. Animal Locomotion (Weidenfeld & Nicolson, London, 1968). 7. Alexander, R. McN. J. Zool. Lond. 173, 549–573 (1974). 8. Lee, D. V., Bertram, J. E. A. & Todhunter, R. J. J. Exp. Biol. 202, 3565–3573 (1999). 9. Gregersen, C. S., Siverton, N. A. & Carrier, D. R. J. Exp. Biol. 201, 3197–3210 (1998). 10. McGuigan, M. P. & Wilson, A. M. J. Exp. Biol. 206, 1325–1336 (2003).