Bring your hands out to the sides as much as you can without letting your chest touch the floor. Your body should form a cross or a T.
Keeping your body rigid and breathing normally, hold this position for the prescribed duration.
Comments and tips
In addition to activating the core like most plank exercises do, the iron cross plank also significantly activates the lower pectoralis major and anterior deltoid muscles because the arms are brought out to the sides. These muscles are isometrically activated.
The iron cross plank is an advanced exercise. Only attempt this after mastering the high front plank.
Keep your body in a straight line from head to toe. Do not allow your back to arch or your belly to sag.
Make sure your neck is in neutral position. Do not tuck your chin.
To make the iron cross plank easier, do not bring your hands out as wide to the sides. To make it more difficult, add a weight plate to your back.