Blender to Unity rig : Distend arm

I have rigged a model in blender with meta-rig which seems ok (her upper-arms in T pose in blender are ok)

But in Unity the upper-arm shoulder looks distend and the muscle are in bulk (.blend and .fbx file give me the same result):

When i play with vertex group weight it doesn’t change that much in Unity.

Any suggestion to save that poor model from contortion?

Problem solved. There were two separated problems.
Distend arm problem came from a bad skinning (at least for Unity).
Muscle problem came from useless stuff in blender file (meta-rig, WGT objects and some DEF objects)