The High jump is a very simple and beautiful event when done correctly. Like most sports or events either the coach or the athlete have complicated the simplicity. I like to say that every event has a trigger. The job of the coach is to identify that trigger and then find a way to convey the importance to the athlete of mastering the execution of that trigger. For example, the sprinter in the blocks is triggered by the arms, the long jumpers trigger at take-off is he knee. Likewise for the throwing events the trigger is the free arm elbow. When looking at the high Jump the trigger is having a very quick, tight, and aggressive knee punch. Most high jumpers give away everything they gained in great run by over extending the take-off leg and trying to load up. This in returns delays the knee punch and the arm movements. As the dominos continue to tumble this cause the athlete to open up on top of the bar and travel well down the mat. This extended exposure in the air most often results in knocking the bar down. The Main objective to the event is to go vertical and pull the heel up tightly to the butt. The end result is a beautiful knee punch where the foot does't get outside of the knee and the athlete stays vertical and doesn't jump into the bar. Below you will see a few training clips where we use the box and bands to work on this:
There are also drills many drills that can be done away from the high jump within the warm-up that can and will reinforce the heel-raise and kneepunch.