People say that to take a charge you cannot be moving. But moving in that case means that your chest or knee is not allowed to suddenly get in the way. You are, however, allowed to be moving backward and, if you are staying in one place, you are allowed to move your feet—and you should. By keeping your feet moving, you are prepared to alter your position slightly in case the offensive player tries to cut by you instead of going straight over you.
Remember, there is no time when you stop playing defense and begin taking a charge. There is no time to suddenly pose or become a statue. Stay in the defensive crouch, keep your feet moving and take the contact on your forearm.
From Dick’s book “Stuff”
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