Trunk rocks with the leg circles
The obliques must resist the leg movement; rocking means the core has given up.
Overactive muscles
ObliquesHip flexors
Corrective work
Foam RollHip flexors↗StretchHalf-kneeling hip flexor stretch↗The obliques must resist the leg movement; rocking means the core has given up.
Reduce the circle size to the range where the trunk can stay stable.