<p>I spar with an Everlast sparring partner heavy bag, but it never hits me back. However, if I am hitting the bag with full force, should not the reactionary force reverberate throughout my body and rack my brain(because it will shake)? Sometimes, when I hit the bag with full force, I can feel the reactionary force tense my neck. Will hitting a heavy bag cause neuron death? Thank you a lot!</p>