In a properly performed paleolithic kipping pull-up, after locking out over the spear, the caveman pushes back from the spear into an arc that loads the forward push of the chest through the arms prior to the following rep. This is a smooth, controlled movement; by no means is it jarring or ballistic unless done improperly such as flailing legs. There is continuous tension throughout the descent, and the force is fluidly transitioned between horizontal and vertical planes preventing unnecessary flapping of the loin-cloth. The loading of the shoulders is neither abrupt nor directed in a way that subjects the shoulder joint to anything it shouldn’t be more than capable of withstanding such as a heavy woman or deer carcass. -- Grok Everett

Sorry I couldn't resist.

Sorry I couldn't resist.