http://fitSF.com San Francisco Personal Trainer Michael Behnken, MS, NASM-CPT-PES, CSCS
The total gym twist is a great exercise for your obliques and core.
To ensure you get the full benefits from this exercise, sit up as tall as you can for the duration of the movement.
Keep your core drawn in at all times, keep your arms completely straight and in line with your eyes.
YOU ARE TURNING YOUR WAIST NOT MOVING YOUR SHOULDERS