Wednesday, August 22, 2007

Proper Range of Motion Part 1: Intro & Dips

When you think about incorrect form, you probably think about two types of offenders:

1. People who don't know the proper way to do an exercise, and out of ignorance perform it in an ineffective or dangerous way

2. People who, out of pride, refuse to go through the proper range of motion of an exercise in order to use more weight

An example of this would be a person who does heavily weighted dips, but only lowers himself a few inches. By not lowering his body further, he is placing his muscles in an advantageous position and reducing the amount of force necessary to contract his tricep. If he used less weight, he would be able to feel the same resistance, but would build strength through a full range of motion. One of the reasons isometric exercise isn't as effective as isotonic exercise (such as the use of free weights) is that strength is built primarily around the position that the muscle is in during the exercise. That means that isometric builds strength in one specific attitude, while isotonic builds it throughout a range.

There are those who, recognizing this prideful mistake, swing too far in the other direction. How so? By going through a range of motion beyond what they should, they make an exercise even more dangerous than the shortened movement. Over the next few posts, I will discuss several of the exercises in which too great a range of motion is often used by well-intending people trying to stay strict. The first, to contrast the lifter I mentioned earlier, is the tricep dip:

The triceps are (surprise!) the primary mover in the tricep dip, with the chest and anterior delt heads being secondary movers. The chest becomes involved the more you tilt forward, so a tricep dip requires that you keep your torso as upright as possible.

The shoulder is a fantastic joint. It can go through a range of motion unlike any other in our body. Compare the movement or your arms at your shoulders and your legs at your hips. Unless you are a contortionist, there's a vast difference. In order to be this flexible, the joint, or rather several joints, aren't firmly fixed. There are many small muscles, tendons and ligaments that make up the rotator cuff, and they can be easily injured. As the strength of the major shoulder movers, such as the pecs, lats, and delts increase, care has to be taken to follow strict form, because if the load placed on the pecs strays into the proportionately weak rotator cuff, damage is inevitable.

The human body isn't built to support much weight with the elbows behind the body line. There simply aren't that many real world occasions in which this is necessary. When a large load is supported with the elbows behind the body line, it causes tremendous stress on the AC joint, which is not meant to support tremendous stress. The acromioclavicular joint, or AC joint, is where the clavicle meets the shoulder blade. It is supported by small tendons and an articular disk. The further your elbows move behind you, the more the forces is transfered into this joint, trying to peel your clavicle away from your shoulder blade.

I can't perform weighted dips anymore. My triceps are one of my strongest muscle groups, disproportionately strong. As I added more and more weight to my dip belt, I noticed an intense, sharp pain in my shoulder, right at the end of my collar bone. Luckily, my wife heard me screaming after ever set and insisted that I research it. I was very near serious shoulder damage, and am now prone to pain in the AC joint.

So when I hear about coaches who don't count a dip until your bicep almost touches your forearm, I wince. It seems like the right thing to do, to go through as full a range of motion as possible, but it is a sure path to shoulder surgery.

In any tricep exercise, to minimize stress on the elbow, the forearm and bicep shouldn't make much less than a 90 degree angle. With range of motion, more isn't always better. The moment you notice your dip is causing pain in your AC joint, you need to lighten the weight and consider using the dip only for warm-up, or reduce the amount your elbows travel behind your body by increasing the forearm / bicep angle or leaning forward slightly.

The dip demonstrated on
An article on shoulder pain and the AC

Next: Leg Press

No comments: