Cable Internal Rotation

How to do it

Sit next to a low pulley sideways (with legs stretched in front of you or crossed) and grasp the single hand cable attachment with the arm nearest to the cable. Tip: If you can adjust the pulley's height, you can use a flat bench to sit on instead.
Position the elbow against your side with the elbow bent at 90° and the arm pointing towards the pulley. This will be your starting position.
Pull the single hand cable attachment toward your body by internally rotating your shoulder until your forearm is across your abs. You will be creating an imaginary semi-circle. Tip: The forearm should be perpendicular to your torso at all times.
Slowly go back to the initial position.
Repeat for the recommended amount of repetitions and then repeat the movement with the next arm.

What muscles does the Cable Internal Rotation work?: Mainly the shoulders.
What equipment do I need?: Cable.
Is it good for beginners?: Yes, it is rated beginner level.
How do I track progress on it?: Log each set and beat the weight or reps from last time. Liftrung shows your last set beside the next one and estimates your one-rep max from your sets.

Exercise descriptions: free-exercise-db, public domain.