Researchers at the Royal Veterinary College in North Mymms, UK, used high-speed video to record a significant difference in how two-legged and four-legged animals run around a track. They examined footage from the 2004 Olympics that showed that the runners on the tighter inside lanes were at a distinct disadvantage over those in outer lanes. It seems that, when humans run around bends, they have to lengthen the time their feet touch the ground to compensate for increased centripetal and gravitational forces. The scientists used a Troubleshooter HR camera made by Fastec Imaging Corp. in San Diego to videotape greyhounds on similar circular tracks. These showed that the dogs did not have to deal with such forces because the muscles that they use to bear weight and those used to power their forward motion are separate. The dogs use back extension and torque around the hips to propel themselves, while their forelegs take the brunt of weight support. Understanding the biomechanics of animal and human locomotion could lead to better means of reducing and alleviating injuries for both groups. And it also helps explain why dogs can run rings around humans.