Long arm chain

Dear all,

i have been visited by a Physiotherapist few time ago where he applied a particular tecnique to strech my arm chain.
he blocked with a sling my shoulder and my foot togheter on the left side, while a was laying on the bed.
My arm was along the body and he started moving it on the side reaching the maximum range (to be clear, like making snow angels).

the issue is that the range was very limited with shoulder blocked! really short! and i felt tension all over the arm until the fingertips.

i tried to replicate that situation at home or find another position to elongate that chain without result.
have you any hint?

nobody reply? was my explanation clear ?