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

How Iridium Programs This

Iridium monitors sub-muscle fatigue to ensure recent heavy bracing in compound lifts hasn't already exhausted your obliques before assigning this isolation work. Since this is a bodyweight movement, the AI tracks your repetition performance relative to your current body weight to drive progressive overload. To manage systemic fatigue, Iridium reviews your 7-day history and prioritizes this exercise only when it fits within your Maximum Recoverable Volume for the core.

Form Cues

Press your lower back firmly into the floor throughout the movement
Exhale sharply as you twist and crunch up
Lift one shoulder blade completely off the ground
Visualize bringing your rib cage toward your opposite hip
Control the descent slowly to maximize time under tension

Don't

Don't pull on your neck or head with your hands
Don't use momentum to swing your torso upward
Don't let your hips lift off the floor
Don't rush the movement; avoid bouncing at the bottom
Don't hold your breath while crunching

Common Mistakes

Yanking on the neck
Using momentum instead of muscle contraction
Insufficient range of motion
Lifting the lower back off the floor
Holding breath during exertion

Muscles Worked

This exercise places primary stress on the internal and external obliques, which are essential for rotational power and torso stability. It also heavily recruits the rectus abdominis (your 'six-pack' muscles) to initiate the crunch, providing a comprehensive workout for the entire abdominal wall.