How to throw the Left Hook properly to prevent Injury

[Chris Nagel]

Your elbow should be in line with your shoulders when you land the left hook. If your elbow is too far back when you land it, there will be too much leverage on your shoulder (Think about an arm-bar submission from wrestling). Your arm can't go back any more, and therefore your shoulder absorbs a lot of force causing that familiar twinge of pain.

Another thing you should remember is that you don't want your fist to go past your chin because then you would lose power. At the end of the movement you want to pull you right shoulder back, and then immediately get your arm into position to land your hook.