BYT

Rotate · Bodyweight · Learn first

Russian twist

Sit with the heels light on the floor, torso leaned back, hands together.

Russian twist
  1. 1Rotate the ribs, not just the hands.
  2. 2Keep the chest tall and the low back long.
  3. 3Touch the floor beside each hip, under control.

Easy to miss: A collapsed posture that only flaps the arms.

Muscles

Copper on the figure is a prime mover. The softer tone helps.