You've heard us say it again and again, do not coach out arm swing dislikes if you have not addressed the problems in the lower limbs (including pelvis, hips knees etc). Look at this photo, clearly left hip frontal plane sway, and right arm swing frontal plane sway. It is not a coincidence. Those 2 limbs are neurologically paired. The arm is acting like a ballast in the opposite frontal plane to help her stay centered. She is failing, compensating, but at least not falling over. Focusing on the cause(s) of the left frontal pelvis-hip drift would be our direction, not coaching out the arm swing. We rarely, if ever, coach changes to arm swing. We have posted articles in the past that confirm that arm swing is more passive, and subservient to leg swing motor pathways.
Read on . . .