The shoulder is one of the most mobile joints in the body and plays an important role as either a primary mover or stabilizer for most exercises at the gym.  Due to its high, versatile and often inadvertent usage it can be easily injured.  The best way to protect it is to properly warm it up and strengthen it.  Unfortunately, one of the most common ways people attempt to do this is actually setting themselves up for potential injury and does not even strengthen the correct muscles.

What should you avoid doing??

You have probably seen someone standing in the gym with a dumbbell in their hand and their elbow bent to 90 degrees.  From there, they rotate their arm both towards and away from their belly button (internal and external rotation of the arm).  Many people do this thinking they are working out or warming up their rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis).  They are actually doing more harm than good. Let’s break down what they are really doing…

Biceps isometric contraction and rotation

The first thing to determine is where the resistance is coming from.  In this position, gravity is pulling the dumbbell down toward the ground which strains the biceps isometrically without challenging the rotator cuff.  An isometric contraction is when the muscle is working to maintain the same length and position without actively moving.  As the biceps muscle tightens, the tendon tightens as well.  The biceps tendon passes through the bicipital groove at the top of the arm (humerus) before attaching to your shoulder.  The transverse humeral ligament passes over the tendon to hold it into the groove.  When the biceps are contracted, the tendon is placed under stress and made taut.  If you add external and internal rotation to that contraction, you put the tendon under friction and can damage the biceps tendon or the transverse humeral ligament.  Imagine what happens to a rope if you pull it back and forth around a corner.  Eventually the rope will begin to fray.  That can happen to your ligament or tendon.

What should you do instead?

The internal and external rotation motions are very good for strengthening your rotator cuff as long as you pay attention to where the resistance is pulling from.  If you choose to use a dumbbell, you can lay on your side with your elbow bent to 90 degrees.  Your upper arm will do external rotation while the lower arm will control internal rotation.

Using cables and resistance bands are other effective alternatives.  These are the two options I usually recommend because you can move through a wider range of motion for each of those directions.  First position the pully or bands at the same level as your elbow.  Stand next to the cable (not facing it) and keep your elbow at 90 degrees.  For internal rotation, use the hand that is closest to the cable.  For external rotation, use the hand that is furthest from the cable.  To help stabilize the shoulder and isolate the contraction of the rotator cuff muscles while you do this exercise, roll up a hand towel and pinch it between your elbow and ribs.  This will keep you from engaging the wrong muscles.

Summing it all up:

While warming up and strengthening your rotator cuff muscles is important, there is a right and a wrong way to do it.  Adding rotation to an isometric biceps contraction is the wrong way to do it.  Instead, opt for exercises that correctly isolate the rotator cuff.  Not only are you less likely to get injured, but you will also add strength and stability to what is commonly a weak link in the chain that makes up your upper body.