Train the abs with a crunch that brings the sternum down to the pelvis, a leg raise that brings the hips up to the sternum, and daily vacuum work for the transverse abdominis. The rule that makes a crunch work is that the abs do not cross the hip joint, so the hips have to stay locked and only the abdominals move. Do not program ab work before anything that needs heavy core bracing.
When people look at you, their vision goes centrally, which is why a detailed midsection matters so much on stage. A lot of people say abs are made in the kitchen. That is not always the case. You can lose the body fat and still find the development is not there.
It cuts the other way too. As you get flat dieting down for a show, if you do not have enough fullness in the abdominal musculature you can look flat through the midsection and appear less developed than you are.
There is a second reason to train them that has nothing to do with looks. Every hinge, every squat, every leg curl has a bracing component, and the strength of your core is what lets you transfer force from a loading point or joint through the body to another point. So we train the functionality of the core as well as the appearance of it.
| Muscle | What it does | How you train it |
|---|---|---|
| Rectus abdominis | Sternum to pelvis, pelvis to sternum | Crunch and leg raise |
| Transverse abdominis | Forceful exhalation, draws the abdomen in | Vacuum work |
| Internal and external obliques | Rotation | Trained functionally, not for hypertrophy |
The rectus abdominis runs from the sternum down to the pelvis, and its main function is pulling the pelvis up to the sternum, or the sternum down to the pelvis. That is the muscle making the six pack, and it works in the sagittal plane, so that is where our exercise selection lives.
From that function you get two patterns: a form of crunch that brings the sternum down to the hip, and a form of leg raise that brings the hips up. If I had to pick two movements, it would be an abdominal crunch and a decline leg raise.
Can you train the upper abs or the lower abs separately? People will tell you that you cannot, because tension runs constant through the muscle. It turns out the bros are partly right. There does appear to be some regional hypertrophy, with preferential development and more tension in the lower abdominals when you are raising the legs and bringing the pelvis up. But tension relatively does run constant through the fibers, so either movement is still training the entire abdominal musculature. Do both, and stop worrying about the split.
On obliques, from a bodybuilding perspective I do not train them in a hypertrophy instance. They get plenty of stimulus functionally.
This is the detail that separates a real crunch from a hip flexor exercise. The abs do not cross the hip joint. So if the hip is moving, whatever is moving it is not your abdominals.
The problem with a normal rope crunch is exactly that: the hip moves a lot and it is hard to stabilise. Setting up on a glute ham machine solves it, because the hips are stationary and placed on the pad, so you can lock them and move only at the abdominal muscles, taking the sternum to the pubic bone.
The loading on that setup is better than it looks. At the start, the torso angle is not perpendicular to gravity, so that is not the heaviest part of the movement. As you go back into the eccentric you reach the position where the torso is at 90 degrees to gravity, and that is the hardest place to come back from. So it trains a lengthened position rather than only a hard squeeze at the top.
For load, hold a ball or a plate. When that stops being challenging, extend the hands overhead. That lengthens the moment arm and makes it harder, and the overhead position also challenges your ability to keep the rib cage pulled down. Between that and the breath cycle, you are practising contraction, stretch and bracing at once.
The transverse abdominis is the one you see everyone pulling deep vacuums with. Part of its function is forceful exhalation, and from there you can draw the abdomen up and create the vacuum, taking the belly button toward the spine. It is also very important in bracing the core, keeping the sternum over the pelvis.
The technique is specific. Exhale, let all your air out, and once it is out, drive and pull the belly button back toward your spine as hard as you can. Hold that position for as long as you can, which will not be long, because after that exhalation you do not have much air. Part of the practice is getting used to holding your breath and building that capacity. That is how you train the transverse abdominis in its fully contracted position.
Timing matters more here than in most training. Ideally do it fasted in the morning, and ideally after you have had a bowel movement.
Vacuum training is something I would do every single day. It is also trained inside your posing practice, where you learn to hit the vacuum and control your waist across the side poses, which is where it pays off on stage.
There is a bridge movement worth knowing as well: get into the crunch position and cue the transfer from the vacuum into the abdominal crunch, so the two skills connect rather than living separately.
The one rule is not to put ab work right before movements that require a lot of core bracing. You need that core to transfer force in your squats and hinges, and fatiguing it first costs you output where it matters most.
You do not need to do it all in one session either. Structure it across the week: a crunch variation on one day, hanging or decline leg raises on another, with vacuum training interspersed throughout.
That structure is also why the vacuum is the piece to do daily. It is not fatiguing in the way loaded ab work is, so it does not compete with anything else in your programme.
A crunch where the hips are locked, done on a setup like a glute ham machine so the hips cannot move and the abs do the work. Pair it with a decline leg raise, since between them you cover both directions the rectus abdominis functions in.
Partly. There does appear to be some regional hypertrophy, with more tension in the lower abdominals when you are raising the legs and bringing the pelvis up. But tension relatively runs constant through the fibers, so each movement still trains the whole muscle. Do both rather than trying to isolate.
Because your hips are moving. The abs do not cross the hip joint, so anything happening at the hip is not being done by your abdominals. Set up where the hips are stationary and pinned, then move only the sternum toward the pubic bone.
Exhale completely, and once the air is out, pull the belly button back toward your spine as hard as you can and hold for as long as you can. Do it fasted in the morning, ideally after a bowel movement, and do it every day. Building the breath hold is part of the training.
After, never before. Your core has to transfer force in your squats and hinges, so fatiguing it beforehand costs you output where it matters most. Spread crunches, leg raises and vacuum work across the week rather than stacking them into one session.
X-Frame programmes daily waist training, vacuums and contractions, alongside the training that builds the frame around it: capped delts, wide lats, sweeping quads and a small waist.
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John Jewett is an IFBB Professional bodybuilder and physique coach, and the founder of J3 University. He has spent his career competing at the professional level while coaching competitors and everyday lifters through the same training, nutrition, and recovery principles he uses himself.
J3 University exists to make that process teachable. Every course is built on the reasoning behind the method, not just the method, so you can make better decisions about your own physique long after the program ends. The article above is drawn directly from the J3U course curriculum.
