... and not hunched.*Step 4Slowly push the wheel forward. Keep the elbows locked and the muscles tight. The gluteus, abdominal, upper arms, lower back ... strain in the abs, and then use the abdominal muscles to pull back the wheel. Do not to let the back arch at all. All ... , any question ,please feel free to contact us, our professional team assure you immediate reply. 2012 new! AB wheel,AB wheel