One of my favorite abdominal exercises are Russian Twists with a barbell. These are also called "core twists," "full contact twists," or "barbell twists." They're pretty much all the same exercise, with variations on foot position that varies as much as the name.
How do I do these? The first trick is setting up the barbell. You'll need an Olympic bar for these, because you need a thick handle to hold and a rotating sleeve to prevent the bar from tearing up your hands.
The easiest way to do it is to use a "Grappler" if your gym has one:
The Grappler is a special mount that holds the barbell firm to the floor in a pivoting holster, allowing the bar to move relatively freely but not slide around. These are probably the best solution, because you can go hard and fast!
You don't need the bar mount for these, you can also do them with a bar in the corner or against a way like so:
Or mount the end of the bar in a 45-pound plate, like this:
How do I do them? Basically you hold the end of the bar in both hands, and rotate left to right, bringing the barbell down towards your knee. Then swing the bar back up and around to the other side.
You rotate and bend at the hips, not at the lower back - your lower back and abs stay rigid and tight. The exercise impact to those areas comes from resisting the pull of the barbell, not from moving. Take a deep breath and hold your breath behind your "armor" - your abs - and keep them tight.
You'll notice some variations in speed and form in the videos I linked above. This is fine - all have something to recommended them. If you do them fast and hard, you'll get more of a cardio effect, and you'll train your body to deal with very hard changes in direction - you have to stop the speeding bar and pull it back fast the other way. On the other hand, if you go very slow, you get a steady pull the whole way through, forcing your body to deal with a slow change in momentum over a longer period of time. Try both!
If you need to increase the resistance, add weight to the sleeve you are holding. A small amount of weight can dramatically increase the difficulty.
Why do I want to do these? An important, perhaps the most important, function of the abdominal muscles (especially the obliques) and the lower back is to resist rotational stress. This exercise, done properly (twisting the hips, not the back, and tight abs) will force your midsection to strengthen to resist this kind of movement. This will translate to a greater ability to resist unwanted rotation, whether from an accident, an awkward lift, or an unfriendly opponent in a grappling match.
Most workout routines cover flexion of the abs and back, but don't bother with counter-rotational exercises. This is a good one, and it's low-equipment and quite difficult.
How many should I do? One thing is for sure, this is an assistance exercise, not a main exercise. You don't want to do these for maximum efforts. Go higher reps - 10-20 - and multiple sets. Train your abdomen for strength and endurance in this motion, not pure strength...it's just not the kind of movement you want to push to your maximum, because of the danger of going to low reps and heavy. Go lighter and go hard for a higher number of reps, and work up slowly.
大会結果：5/21 JBJJF 第8回中国柔術選手権 | アダルト黒帯で白木大輔がWゴールド
14 minutes ago