timothy h h w ehewitt. for an athlete, for anyone, to what extent can you prevent these injuries?ere are multiple trials demonstrating that you can reduce the risk of an acl injury with with training in the range of 60 to 65%. perhaps two-thirds of the injuries are preventable. >> i imagine they try to do these types of exercises. what are the exercises? are they things people can do at home? >> yes, they are. the exercises basically address ligament imbalance. the knees and hips collapse in together. so the first step is to just educate the player to not allow their knees to collapse together and greater hip control. also, athletes tend to be quadriceps dominant. the big muscle on the front of the thigh. so we turn on the posterior chain of the muscles. glutes, hamstrings. the poster year complex. and players favor one leg versus another. >> you say there are tests to determine whether an athlete or someone at home is more at risk. what would they look for? >> basically there are four simple tests. the first is just to drop off a foot-high box go into a maximum vertical jump and