Too much weight on the head — neck compressed
Most of the weight should be through the elbows; the head barely touches.
Overactive muscles
SCMSuboccipitals
Corrective work
Foam RollSuboccipitals (lacrosse ball)↗StretchSCM / scalene stretch↗Most of the weight should be through the elbows; the head barely touches.
Thoracic stiffness prevents the arch; use a block under the thoracic spine.