1. Where you can get.
2. Around where you can start.
3. Don’t do this please.
see video here: https://www.instagram.com/p/Bu_-X6jHPEy/
Video 1 - how you may one day be able to train abs, if you understand how to train them appropriately (and, if you don’t understand trunk flexion and the difference between hip and spine action, please look back at my prior posts on abs or check the website) - this is a version of the weighted dragon flag; I have 6lb ankle weights on each leg; my primary concern is maintaining the flexed trunk position while changing hip angles in order to lengthen the lever length (increase force need) and decrease the lever length (decrease force need). Another variation would be to fix yourself at the hip and move into and out of maximal trunk flexion. Previously, I showcased that while non-weighted in Secret to Abs, part 1.
Video 2 - with one caveat, this is about where you can start once you’re past the beginner stages. I prefer to keep my legs out in order to lose mechanical advantage, lengthening the lever, and requiring more force. The hip is immobile. The spine is bendin, so there ain’t no pretendin. The distance between ribs and pelvis is closing. Most people can control this if you bend at the knees fully and draw them all the way into the chest while you peel the hips off of the bench. The version I show here would be a several step progression from there.
Video 3 - leg raise - take note of the space between my mid back and the bench. That IS abdomen stretch. So what is a simple leg raise like this doing? Good question. I suppose after 100 to 1000 consecutive reps, I may finally feel the abs because they’ve been stretched for so long. But they aren’t contracting anymore than your bicep is when you hold groceries in your outstretched arm. What is certainly working is the psoas major, minor, and ileacus. And the first has its origin on your T12 through L5 vertebrae. I don’t know about you; but I’d like to work abs and not back pain when I work abs. Likewise, the way people do Roman chair and toes-to-bar is generally NOT intelligent ab training. It’s hip flexor and low back pain tolerance training.