Over the past few years, the situp has been phased out by exercises that require you to keep your spine stiff (think: the plank). That's because rounding your lower back over and over again--like you do during situps--can lead to back pain. But Todd Durkin, C.S.C.S, author of The IMPACT! Body Plan, wants to bring the move back from the dead.

"Occasional situps won't cause lower-back issues," says Durkin. "The real problem is sitting for multi-day, lengthy periods." The neutral curve in your lower back is crucial, and sitting all day at your desk, in the car, and on the couch flattens it. This causes the gel at the center of your discs to herniate or rupture their casings, leading to pain. For chair junkies, situps push the gel out even further, exacerbating the problem. (If you are stuck at a desk, here’s the one exercise you must do to prevent and cure back pain.)

So rise up and stand more frequently at work. Here at Men's Health headquarters, we are believers: 71 percent of MH editors are using standup desks now.

"You shouldn't be a slave to the chair, because the situp it one of the best ways to work your midsection dynamically under tension," says Durkin. The result: Stonger, more sculpted abs. (For an even bigger challenge, check out these 3 All-New Ab Exercises--no crunches required.)

That's why he created this weekend's fitness challenge around the exercise. The test: Do as many situps as you can in one minute. Yep, you may remember this one from gym class! Can you beat your old score?

Here's how it works: Grab a stopwatch. Lie with your knees bent and your feet flat on the floor. Have someone stand on your shoelaces so you are anchored there. Hold your hands behind your ears. Keeping your hips on the ground, lift your upper body and bring your chest toward your knees. Lower back down. Perform as many reps as you can in one minute. You can stop whenever you like, but keep the clock running the entire time.

Ready to try it? Watch the video above to see Durkin perform the challenge. He completed 47 situps in one minute. How many did you perform? Let us know in the comments below.

If you work out but can’t seem to see your abs in the mirror, you’re probably doing something wrong. Check out The Best Abs Workout Ever to blast belly fat and sculpt a six-pack at the same time.

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