To get six-pack abs, most people think they’ll have to do hundreds of crunches. But crunches involve spinal flexion (rounding forward), and research shows that spinal flexion can lead to herniated discs. Knowing this has sent me on a long and exhaustive search for safe and effective ab training.

Last week, I stumbled onto a new study supporting my “ab crunch ban” and my preference for exercises such as the “side plank.” In this study, researchers examined six common ab exercises performed by 120 subjects to see how hard the muscles were working.

When compared to other common ab exercises, the side plank and the classic abdominal crunch both resulted in the greatest change in muscle thickness for the transverse abdominis and internal oblique muscles (meaning they were contracting the muscles more than the other exercises). However, because the side plank does not involve spinal flexion, and because it builds abdominal endurance (previously found to be associated with less low-back pain), the side plank wins this exercise battle hands down.

If you are looking for a new move to add to your total-body fat-burning workout, the side plank is the way to go. To do it, lie on your right side. Bend your right arm at the elbow and stack your left foot on top of your right foot. Supporting your bodyweight on your right forearm and your right foot, raise your body in a straight line. Your butt and thighs should hover a few inches above your mat. Keep your back straight and your hips up. Hold your abs tight, but breathe normally. Beginners should hold this position for 15 seconds on each side. Try to hold it a little longer with each workout. For advanced core strength, hold for 45 seconds per side.

[Ed. Note: If you think sit-ups and crunches are the best way to get a flat stomach, you’ve fallen victim to one of the most common fitness myths around. Discover 5 more myths about exercise – and how to combat them – right here.]

Craig Ballantyne

If you want to double your income, work less, and become the ambitious millionaire you've always wanted to be... Craig Ballantyne is the coach who will help you do it. With more than 20-years of experience as an entrepreneur and five 7-figure businesses under his belt, he specializes in helping "struckling" entrepreneurs get out of the mud and build the business of their dreams. To see if you qualify for Craig's "Millionaire Coaching Program" send an email to support@earlytorise.com with the subject line "Millionaire".