If you want to build REAL core strength..and I mean BRUTE core strength that will support massive weights, forget the Bosu ball and forget crunches...you need to do exercises like the One Shoulder Barbell Squat that I'm going to show you today.
It's another entry into my long list of exercises that work the abs while not looking at all like an ab exercise and working BETTER than most ab exercises.
This one is basically a squat...so how does it work the abs? Very well, thanks!
Seriously, though, this exercise is EXTREMELY effective at targeting the stabilizing and core strength aspects of the abs. You'll be doing a barbell squat but instead of supporting the bar across your back in a "normal" fashion, you will instead be resting it on one shoulder, standing perpendicular to the bar.
It's going to primarily hit one side of the abdominal wall and hit it in conjunction with a squatting movement, which means this is a VERY functional exercise. More so than most abdominal exercises, in fact!
Here's a snapshot of what it looks like in the start position.
As you can see, I'm facing sideways in the rack. The safety rails are set at a moderate position (not a full depth squat). You'll be starting off from the bottom of the movement with the bar resting on the rails and, for best results, you don't want to be starting at the bottom of a full squat - it's low, but not too low.
I would recommend using a bar pad for cushioning or a rolled-up towel, otherwise the bar really digs into your trap as you're doing the exercise. Use a lighter weight than you think you'll need the first time you do this (trust me). I've got 225 lbs on the bar here and can regular squat double that and it was challenging.
Your shoulder is set as dead-center on the bar as you can manage (you'll be able to feel the balance point on the first rep and adjust from there).
You want to have your hands out in front of you and locked onto the bar to help control it. You can use upwards or downwards pressure to adjust the balance as you stand up.
Come all the way up to the standing position.
Here's the other side view of the exercise. You'll notice that my working-side arm's elbow is point directly out to the side and my arm is held up. Holding the arm up like this helps keep the bar from rolling out to the side
A few other views...
It's a very straightforward exercise that will have a HUGE impact on not only your entire abdominal area but your entire BODY as well. Supporting the weight in this off-center fashion challenges not only the abs but the shoulder girdle and legs as well.
It's truly a total-body ab exercise!
When you've done one side, you can either turn around and go immediately to working the other side or take a rest in between - whichever way you prefer. If you go directly from one side to the other, on your next set, start with the different side so you give it balanced workload.
As I mentioned above, the first time you do the exercise, start fairly light to get an idea for how it works. I like to set the bar down on the rails in between reps to reset the core and legs and make everything is properly aligned before doing another rep. With the resistance off-center on your body this is helpful in preventing injury because of compromised body position.
I'll tell you this much...the first time you do this one, your entire core will be sore for several days after. You'll feel that pleasant tightness that tells you that you accomplished something with your core training!