A Flaw in CrossFit - The Kipping Pullup

Pullups should be made one of the core exercises of any strength program.  It is a closed chain, compound movement that utilizes a multitude of muscle groups.  However, like many exercises, you can be doing as much, or more, harm as good to your body if they are done incorrectly.

The Proper Form of a Strict Pullup

Grip the bar slightly wider than shoulder width apart, and start with arms fully extended.  This is known as a "dead hang".  Pull until your entire head clears the bar, keeping your legs in a stationary position.  Descend quickly, but in a controlled fashion; do not just relax and let yourself drop on the eccentric, or negative part of the movement.  Repeat for as many repetitions as you are able.

What is Kipping?

Kipping is the common method of cheating when doing pullups.  It is the throwing up of the legs, thereby using the momentum of your body to assist in clearing your head above the bar.

Why is Kipping Harmful?

 A compound exercise involves more recruitment than just the targeted muscle groups.  In the case of pullups, those prime movers, or agonists, are the upper back - the latissimus dorsi, and the rhomboids.  The secondary movers are the biceps.  The antagonistic muscles in the pullup movement serve as stabilizers, keeping the movement of the body under control.  For pullups, these are the shoulders and triceps.  Frequent kipping leaves the shoulders significantly vulnerable to injury.

The rotator cuff consists of four different intersecting muscles and a circular piece of cartilage called the labrum.  This is where the problem occurs.  Whenever you are using a cheating method for any exercise, you are doing so because your agonist muscle group is either:
a.  not strong enough to handle the weight you are using to do the repetition(s) in correct form if the cheating is used through the entire set, or,
b.  in cases of cheating to execute a few more repetitions at the end of a set where you have started out with proper form, the muscles are too fatigued to continue.  In other words, you have experienced momentary muscular failure.

The shoulders are what is known as a small muscle group.  They are, indeed, much smaller than the muscles that make up the upper back.  The exertion of force and momentum upwards that the back cannot handle causes a rapid, uncontrolled descent on the negative.  If the muscle and the cartilage cannot handle the weight, the extra stress will transfer to the bones and ligaments.

The Correct Alternative

This is, of course, correct form.  A question many will address is, "What if I'm not able to do even one correct pullup?"  Many gyms have a pullup assist machine.  It has a weight stack attached to a platform that you either kneel or stand on.  This serves to counterbalance your own weight.  The more weight you put on the stack, the less weight your back is actually pulling. 

Other alternatives to the pullup assist machine are incline body weight rows.  This is like a pullup, only your feet remain on the floor and you pull your weight at an angle.  Other paths to developing your way to the first pullup are lat pulldowns, seated rows, and dumbell rows.