A biomechanical analysis of running elephants has revealed that Earth’s largest land animals do some strange things at high speed.
Unlike every other quadruped, they use all four legs for braking and propulsion, rather than rather dividing those tasks between hind and front legs.
Elephants also prove to be extremely inefficient while running. Compared to animals like horses, they perform quite poorly. Then again, given their size, running itself is quite an achievement.
http://www.wired.com/wiredscience/2010/03/elephant-biomechanics/