Exercise movement reviewed by:Marie Braga, PT, DPT, CSCS

How Iridium Programs This

Iridium credits this movement toward volume landmarks for both your upper abs and obliques due to the combination of spinal flexion and lateral bending. Because the unstable surface limits your maximum strength output, Iridium relies on your set-by-set RPE rather than standard 1RM formulas to gauge intensity and regulate progressive overload.

Form Cues

Kneel securely on the dome with your glutes resting near your heels
Lock your hands against your forehead or upper chest throughout the set
Crunch down by bringing your elbows toward your thighs, then flex laterally to one side
Control the cable resistance slowly as you extend your spine back to the start
Keep your hips stable to ensure the movement comes from your spine

Don't

Don't pull the rope down using your arms or shoulders
Don't sit all the way back onto your heels during the crunch
Don't rush the side bend; pause to feel the oblique contraction
Don't let the cable jerk your body back into extension
Don't tuck your chin excessively into your chest

Common Mistakes

Pulling with the arms
Using momentum to crunch
Sitting back on heels
Rushing the eccentric phase
Limited range of motion

Muscles Worked

This exercise primarily targets the rectus abdominis through spinal flexion and the internal and external obliques through the added lateral bend. The unstable surface of the balance trainer recruits deep stabilizing muscles like the transverse abdominis, while the forearms remain engaged to hold the rope attachment.