Take off your shoes & socks. Now sit in a chair,ideally one like your pc chair. Sit with your thigh & shin at right angles, do a calf raise & hold it at the top. If you look at your big toe you'll see that its bent at more than 90 degrees to your foot. Compared to the other toes you should be able able to get an idea how much power & change of direction comes from your big toe when pushing off. Turf toe is caused by over extending the big toe beyond the maximum natural flexion of the joint. Go back to the position of the calf raise when seated as above. Lean forward in your chair to over extend the toe joint, press down cautiously through your foot as if your going push off & you should feel a slight discomfort in the large tendon that runs along the top of your big toe. Now imagine a RB in a full speed run with his foot planted as described above,as he his pushing off his back foot he gets hit hard by a linebacker & driven back. The planted foot has knowhere to go & the big toe joint is overextended. It can also happen under less extreme situations if a bad shoe is worn or if a shoe is taped incorrectly. In this case as the foot is flexed in the shoe,the material over the toe joint flexes inwards & down onto the toe joint causing unatural pressure on the joint. This problem is made worse by a bad taping job behind the point where the shoe flexes, forcing a hard edge down onto the joint of the big toe. Once a turf toe injury has occurred even minimal flexion of the joint can be extremely painful.Turf toe injuries are debilitating to any explosive type of athletic sports. Often a player will get through a season with turf toe by taking a painkilling injection direct to the toe joint prior to a game. Between games he'll recieve a lot of ice treatment to reduce the swelling & also wear a boot that prevents him from flexing the toe joint in order to completely rest it. When a player has a turf toe injury it can take a very long time to heal because blood flow to tendons is minute. Because of this even surgery is often not beneficial to a turf toe injury as recovery is again hampered by poor blood flow. The name comes from the frequency injuries occur when playing on artificial turf. The high grip surface often leads to a players foot getting 'jammed' or stuck in position on the turf whilst his upper body is being tackled & driven backwards. On natural surfaces a players foot is more likely to slide out of harms way although modern cleats can still cause the foot to get caught in the turf & cause a turf toe injury.