Light pipe, big payoff for shoulder health.
Keep elbows glued to your ribs, all movement comes from the shoulders.
With both elbows pinned to your ribs and bent to 90 degrees, rotating the pipe outward trains the shoulders' external rotators, the small muscles that keep the joint centred during pressing and pulling. Holding one pipe with both hands links the arms together, so a lazy side cannot hide and the tempo stays controlled. It earns its place as cheap insurance in warm-ups, keeping the rotators switched on before the heavy stuff.
The pipe connects both hands, forcing symmetrical range and honest tempo. Freehand rotations are easy to fake, the pipe tells on you immediately.
Yes, that turns rotation into arm swinging. Squeeze a towel between each elbow and your side if you need a reminder, all the motion should come from the shoulders rotating.
Before every pressing or overhead session works well. A couple of slow sets of 10 to 15 is enough, this is maintenance work, not a max effort lift.
