I’ll share what I picked up from the run clinic. During the previous run clinic, they kept referencing that your arm swing should be from “nip to hip.” I can’t remember what the demonstration looked like, but I interpreted that to mean that your hand would be crossing across your body up to your chest and then diagonally down to the hip. In this run clinic, Coach AJ shared that she recently did a marathon and when she reviewed the pictures she saw her form was breaking down and her hands were crossing in front of her body. The arms should be going straight out in front of you and straight back without any crossover.
Just wanted to share in case anyone else misunderstood that!