Tip: 3 Exercises That Beat Boring Planks

I first came across this exercise in the book, "Underground Secrets to Faster Running," by Barry Ross. No matter how strong you think your core is, Ab 45s will humble you! Here's how you do it.

• Lie on your back with your knees bent and hook your feet under something stable, like a machine or two heavy dumbbells. Or get a training partner to hold your feet down.
• Scoot your butt as close to your heels as possible. Extend your arms out fully overhead and keep them in line with your torso throughout the set.
• Raise your head and trunk up to a 45-degree angle. Make sure to bring your arms along with you, keeping them fully extended and in line with your torso.
• Hold that position for a solid 5-second count and then lower your head and trunk back to the floor. Take a breath at the bottom and repeat the process.

Build up to 5 sets of 5 reps with 5-second holds, and gradually work your way up to holding each rep for 10 seconds.

If starting from the bottom-up is too tough, try going from the top-down with this exercise.

I discovered this one in Nelson Montana's e-book, "The Bodybuilding Truth." According to Montana, abdominal development is genetically determined and classic movements such as sit-ups and leg raises are ineffective for the abs but extremely effective for the psoas (hip flexor) muscles.

Montana believes that the abs respond best to contraction, not movement, and are stressed to a much greater degree when attempting to stabilize the core. You'll understand what "attempting to stabilize" means once you try the exercise.

• Sit on the ground with your legs bent to about 90 degrees and your feet flat on the floor.
• Tuck your chin into your chest, round your back, and grasp the outside of your knees.
• Now lean back until your arms, still holding your knees, are straight. Make sure to keep your chin tucked in and back rounded.
• Once your arms are fully extended, slowly raise them up until they're pointed directly overhead. If you find it difficult to maintain balance, you can move your feet out a bit to make it easier. The closer your feet are to your hips, the more challenging the exercise is, and vice versa.
• Hold the contraction for 5-10 seconds and repeat. Work up to the point where you can do 10-12 reps.

This exercise requires no equipment and can be performed anywhere. Drop to the floor right now and give it a shot. You'll be surprised at how challenging it is.

A word of caution: It's not uncommon to cramp on these isometric exercises. Make sure you're well hydrated and once you start to struggle, stop. Listen to your body. If you try to push on, you'll cramp, which is your body's way of forcing you to stop. Take it slow and gradually ramp it up over time.

This is a great antagonist movement for the above moves. Do it on a back hyperextension or glute-ham raise machine.

• Extend your arms fully overhead and keep them in-line with your torso throughout the set.
• Raise your upper body up until it's parallel to the ground and hold that position for a strict 5-count. Then lower back down and repeat.
• Build up to 5 sets of 5 reps with 5-second holds, and gradually work your way up to holding each rep for 10 seconds.

All of these exercises make for great finishers. You can pair the ab exercises with the back extension in a superset fashion, or you can alternate between doing an ab exercise at the end of one workout and the back extension at the end of the next workout.