Fitness experts agree that sit-ups are worthless — here are 9 moves they recommend instead

From celebrity trainers working in the trendiest Manhattan gyms to the National Institute for Fitness and Sport in Indianapolis and the US Army training exams, sit-ups are developing a bad reputation.

Scientists have discovered that the moves, once a staple of basic workout routines, don't reduce waistline circumference or trim belly fat. Sit-ups are also not the best way to strengthen your core or to keep it flexible and strong for the long run.

Last week, the US Army announced that after decades of requiring two-minute sit-up tests, it would phase out that portion of its fitness test by the end of 2020. Instead, the Army says it'll make room for some fitness tasks found to be more useful for soldiers' combat readiness, like deadlifts, power throws, and drag-and-carry moves, The Washington Times reported.

It's a change that Tony Maloney, a trainer and exercise physiologist at the National Institute for Fitness and Sport in Indianapolis, can get behind.

"I'm not a huge fan of sit-ups," Maloney told Business Insider earlier this year. "Reason being, it can cause some spinal problems, especially if they're not done properly."

Here are some other expert tips for getting a stronger, more flexible core:

SEE ALSO: A celebrity fitness trainer reveals 3 dynamic ab, arm, and glute moves you can do at home for a summer beach bod

The celebrity fitness trainer Anna Kaiser says that many people are doing their crunches wrong and that it's making their belly bulge.

"When they do a crunch, they push their abs out," Kaiser told Business Insider recently. "Which actually will assist in that rounded lower-belly shape." 

The key to a strong core, Kaiser says, is a fit transverse abdominis — that's a deep-layered muscle that sits between your ribcage and your hips.

If you want your abs to appear flatter and be stronger, you have to strengthen those deep core stabilizers, Kaiser says. Try this move:

Sit on the floor with your knees bent, feet flat. Take hold of the area behind your knees with your hands and pull in your abs while tilting your pelvis forward. This will create a C-shaped curve in your spine. 

Now, raise your arms and press them toward the back of the room in little pulses.

Push-ups are also a great multipurpose exercise that gets at your core and other parts of your body.

Maloney said the benefits of push-ups were unbeatable. From your arms and shoulders down into your core, they strengthen the entire spine:

"You're getting that upper-body toning effect, but you're still working the trunk," he said.