Great exercise for your core. The stability ball adds an extra challenge because it is an unstable surface. This forces more activation from your core muscles to maintain your balance in the plank position.
Näin teet sen
Position your forearms on top of the stability ball and walk your feet backwards until your body forms a straight line from your head to your feet.
Your body should be supported only by your forearms and toes.
Hold this position for the desired period of time.