How to build strong, defined abs by doing the bare minimum amount of exercise

• You don't need to do thousands of sit-ups or spend hours in the gym to build abs. 
• You can instead do the bare minimum of two to three ab-focused exercises for 20 to 30 minutes a week. 
• Exercises like the hollow body hold or heels up crunch are great options that are both basic and effective.

It's natural to think that building strong, defined abs requires a combination of multiple days in the gym and thousands of crunches or sit-ups. But what if you don't have that kind of time to dedicate to it and instead seek the bare minimum? 

Just like how personal trainers now recommend skipping crunches, it's also possible to give your abs a thorough workout without having to spend much more than a couple of hours on them each week. Plus, you can make solid progress by doing only a handful of simple exercises.  

"Those elusive stomach muscles don't necessarily have to come from doing 1000s of crunches," says strength coach and owner of Redefining Strength, Cori Lefkowith. She adds that people of all fitness levels can instead build defined abs by focusing on refining their diet and doing the bare minimum of ab work — about two to three effective ab-targeted routines per week for roughly 20 to 30 minutes per workout.

Below are five basic, bare minimum ab exercises perfect for anyone looking to work their core, as recommended by Lefkowith. 

#1: Banana hold (or hollow body hold)

The banana hold is a "great isometric option, like the plank, that doesn't involve your shoulders," says Lefkowith. It's still a very challenging move that works all areas of your core. 

"When starting out, you may need to raise your legs higher and keep them hovering just off the ground as you reach your arms up overhead, crunching your shoulder blades up," Lefkowith adds. "Think about that slight tuck of your hip bones toward your ribs as you hold to engage your abs."

How to do it: 

• Lie on your back with your legs flat on the ground.
• Engage your core and reach your arms overhead, pointed toward the wall behind you.
• Squeeze your shoulder blades together as you lift both legs off the ground.
• Try to keep your legs as close to the ground as you can, roughly six or so inches.
• Hold this position for 30 to 60 seconds.
• Do three to four total sets.

#2: Heels up crunch

Lefkowith says she loves to include a combination of exercises that flex or bend the spine with anti-flexion movements like planks to build more functional strength. This combo also delivers a simple, effective workout. 

"The basic crunch is often demonized but it's a great move to isolate the abs and focus on core stability," she says. "By pressing your heels into a bench, table, or couch, you can better engage your lower abs."

How to do it:

• Lie on your back with your hands behind your head and put your feet onto a slightly elevated surface like a bench or a coffee table.
• Engage your core and press your heels down into the elevated surface as you lift your shoulders off the ground while doing a crunch motion.
• Lower back down to the starting position and repeat the move 10 to 15 times.
• Do three to four total sets.

#3: Reverse crunch roll

The classic crunch gets upgraded by adding a rolling element that works your entire core. Lefkowith loves using this move to target lower abs, to work on achieving that 'V' shape, and to build all-over core strength.

"To get more out of this exercise, focus on rolling up one vertebra at a time to tuck your knees in toward your elbows," Lefkowith says. "Don't just flex or extend at the hips — you need to really flex your spine to work your abs."

How to do it:

• Lie on your back with your hands placed underneath your butt, your knees bent, and your feet flat on the floor. 
• Engage your core as you press your feet into the ground and lift your hips up off the floor.
• Continue to slowly lift your hips off the floor one vertebra at a time, holding at the top of the extension for a few seconds.
• Slowly roll back down and repeat the move 8 to 10 times.
• Do three to four total sets.

#4: Body saw

Let's be real: planks can get crazy boring. If you're someone who can't stand holding the same position for too long, Lefkowith encourages you to try out the body saw. 

"For a twist on the basic plank that's even more challenging, the body saw is a great option," she says. "You start in a standard forearm plank position but then walk your feet backward, elongating your body through your shoulders. You'll feel your abs really working to protect your spine."

How to do it:

• Start in a forearm plank position with your elbows directly under your shoulders, feet hip-width apart, and your spine long and neutral. 
• Walk your feet back, alternating one foot at a time while maintaining the plank position.
• Stop when you feel your abs begin to tighten, and then walk your feet back to the starting position. 
• Repeat the move 8 to 10 times.
• Do three to four total sets.

#5: Side plank hip dips with rotational reach

Every solid ab circuit needs some targeted oblique exercises, and these side plank hip dips are exactly that. According to Lefkowith, these really activate the sides of your core without putting your spine through any unwanted rotations.

"Side planks like this are unilateral core movements that work each side independently to help correct imbalances," she says. "I find moves like this great for anyone who wants to target the 'love handle' area."

How to do it:

• Start in a side plank position with your feet unstacked and your eventual top foot placed in front.
• Line up your elbow underneath your shoulder, have your hips lifted, and your core engaged. 
• Dip your hips twice toward the ground and then get back into a full side plank position.
• Rotate your torso forward to face the ground and reach your arm under the armpit of the side closest to the ground.
• Shift back into a full side plank position and repeat on the same side for 8 to 10 reps before switching to your other side.
• Complete three to four sets per side.

Insider's takeaway

Doing thousands of crunches a day isn't the only way to build strong, defined abs. You can instead do the bare minimum and take a smarter, more efficient approach to working your core by doing a handful of ab-targeted exercises for 20 to 30 minutes a few times a week.

Moves like the banana hold or reverse crunch roll are great for working everything from your lower abs to your obliques. These not only help you strengthen your core, but they also allow you to work toward that coveted V-shape and can help make everyday tasks a little easier.