Before we get into that, let's take a look at the trunk musculature. The primary muscles in the trunk are the transverse abdominis, rectus abdominis, and internal and external obliques.
- The rectus abdominis are the 'abs' that all the 6-pack hunters are looking to develop. Their primary function is trunk flexion.
- The transverse abdominis is a deep stabilizer muscle that acts like a corset to stabilize the spine and pelvis.
- The obliques bend and rotate the trunk. They also function to resist rotation and side flexion.
If you're only doing situps or leg raises in hopes of a strong 'core', your ab workout sucks. You need to add in some bracing exercises, trunk rotation and exercises that force you to resist rotation. Stop doing so many crunches and start doing some of these.
Planks - if you're new to these, here's where you start. Get on the floor in a prone position. Get up onto your elbows and knees while keeping your back flat and neutral. Don't sag at the hips, don't let your shoulders drop, keep your core tight, and hold for time. Once you can hold this position for a minute, move from your knees to your toes. After you can hold that position for 2 minutes, start doing them with 1 foot raised. The same exercises can be done as side planks and the same progressions apply.
Woodchoppers - In a cable cross machine, set the pully in a high position. Stand perpendicular to the pully with the handle on your left side. I find that using the rope handle helps with grip. Hold the rope like you would a baseball bat with your left hand over the right in in an under/over grip. Pull the handle down and across your body just like you would if you were swinging an axe to chop down a tree. Switch sides after 5-10 reps. Be sure to keep your hips and pelvis locked in place so that all of the rotation comes from your thorasic spine/mid back. Remember - lumbar rotation bad... thorasic rotation good. To progress, you can lower the pulley to the middle position and 'chop' straight across your body like swinging a bat or set the pully to the low position and 'chop' across and up.
One arm DB bench press - This one is done just like it sounds. Lay on a bench with a single dumbbell and press it. Start with a weight that's around 50% of what you normally press with... you'll be surprised at how difficult it will be to stay on the bench.
One arms standing cable row - Go back to the pulley machine. First, set the pulley to the middle position. Next, take a few steps back so that the stack comes up a few inches. Then sit back into a parallel squat position. Extend your arm and start rowing. Don't allow any trunk rotation throughout the movement and keep your hips/knees/shoulders locked into position.
One handed farmers walk - Grab a moderately heavy DB (or farmers walk handle if you're lucky enough to have some available) in one hand and walk. Easy. Ok, the exercise itself isn't easy... just the description.
Add these exercises into your routine and you'll see a bigger squat, DL, and fewer injuries (assuming the rest of your routine doesn't suck as bad as your ab routine does). And for those of you looking for the coveted 6-pack, the best exercise is pushing yourself away from the dinner table.