If you can do a ton of weight or a ton of reps on this exercise, you're doing it wrong. Here's how to make it really work.
Isolation ab exercises are mostly a way to improve the mind-muscle connection with the abs. When doing isolation work, the goal is not to use more weight or do more reps – it's actually to try to fail with as few reps as possible!
This indicates that you're good at tensing your abs hard, so they fatigue sooner. If you have to do 20 or 30 reps to feel your abs, you suck at recruiting them.
When doing an isolation exercise like the cable crunch, there are two things you have to do:
- Before starting a rep, contract the abs as hard as possible. Imagine you're about to get punched in the gut. Every rep should start this way.
- When initial tension is established, CURL your torso. (It's not a flexion, it's a curl/rolling action). When you roll forward and reach the end of the range of motion, again tense the abs as hard as you can and return to the starting position.
The Most Important Point
The goal isn't really to "crunch" but to shorten the distance from the pelvis to the sternum. Your hips come forward as your upper body "crunches." Try to touch your junk to your chest.