7 best gym machines for building abs

a photo of a man doing crunches on a machine at the gym
(Image credit: Shutterstock)

Whether you’re training for your first 5K or just want to move around in the world a little easier, strong abdominals are a must. As the literal “core” of our bodies, the abs are responsible for everything from stabilizing your body to flexing and extending your spine, to keeping your vital organs protected and in place. 

Rolling out your mat for a few rounds of sit-ups, crunches, and planks will definitely work your abs at first (and will always be a great warm-up, no matter your fitness level). Once those muscles start getting more conditioned though, you’ll need to look for ways to make your core routine more challenging.

The next time you head to the gym, try hopping on one (or all) of the 7 best gym machines for building your abs. After only a few sessions, you’ll be able to reap the rewards from a strong and conditioned core.

What are the abdominal muscles?

Your abdominals are made up of several different muscles: the transverse abdominis located deep in your torso and connected to your spine and pelvis, the rectus abdominis which is the superficial “six pack” grouping of muscles, the internal and external obliques that frame the sides of your body, and the pyramidalis which is a small triangular muscle in the pelvis.

7 best gym machines for building abs

The biggest benefit to gym machines is the ability to widely adjust their settings, making them appropriate for everyone from the professional athlete to the novice exerciser. Keep in mind that not all gym machines are designed the same — you may see some minor differences between the descriptions below and how your machine operates. If you’re a gym newbie, consider scheduling a few sessions with a certified personal trainer to ensure correct form and appropriate weight selection. 

1. Seated crunch machine

The seated crunch machine takes the basic crunch, rotates it upright, and adds some weight to amp up the difficulty. 

To use the seated crunch machine, adjust the machine settings for your height and select an appropriate weight. Place your shins underneath the leg pads and grab the top handles. Engage your abdominals and lift your legs up as you crunch your upper body and torso forward. Return to the starting position with control. Continue for 10 to 12 repetitions.

2. Rotary torso machine

Want strong obliques? The rotary torso machine will target those muscles along with the rest of your abdominals, making it a super efficient and effective choice for your core days.

To use the rotary torso machine, adjust the machine settings for your height and select an appropriate weight. Choose the direction you’d like to perform the exercise in first and adjust the bottom pin appropriately. Take a seat with your feet flat on the floor and your back pressed against the pad. Grab the top handles and align your elbows slightly below your shoulders at a 90-degree angle. Engage your core and slowly rotate your upper body in a clockwise direction. Once you’ve reached the end of your range, return to the starting position with control. Once you’ve finished your set, repeat in a counterclockwise direction by adjusting the bottom pin appropriately. Perform 10 to 12 repetitions in each direction.

3. Decline bench

The decline bench uses the power of gravity to work your rectus abdominis and transverse abdominis. When gravity alone is no longer difficult, grab a dumbbell, kettlebell, or weighted plate to advance the exercise.

To use the decline bench, adjust the angle of the bench to your desired level. Place your shins underneath the leg pads, locking your feet against them for stability. Cross your arms against your chest, keep your core engaged, and slowly lower your body onto the bench. Inhale deeply. As you exhale, squeeze your abdominals and lift your head, shoulders, and torso off of the bench until you’re back to the starting position. Continue for 10 to 12 repetitions.

4. Captain’s Chair

This aptly named gym machine allows for a lot of exercise variability — you can work nearly every muscle of your core in a multitude of different ways. We’ll go over Captain’s Chair knee raises here, but don’t be afraid to branch out and try other exercises once your abs get stronger. 

To use the Captain’s Chair for knee raises, step both of your feet onto the platforms. Place your forearms onto the arm pads and grasp the handles. Roll your shoulders back and squeeze your shoulder blades together, pressing your back into the pad behind you. Engage your core and slowly lift your feet off of the platforms. Bring your knees together, bend them at a 90-degree angle, and lift them so that they are aligned with your hips (as if you’re sitting in a chair). Keeping the abdominals engaged, slowly lower the knees towards the floor. Lift them back up to the starting position with control. Continue for 10 to 12 repetitions. 

Read what happened when this fitness writer did 50 Captain’s Chair crunches a day for a week here. 

5. Assisted pull up

You may think that the assisted pull-up is only good for building a strong upper body, but this gym machine is great for strengthening your abdominals as well.  

To use the assisted pull-up machine, select an appropriate weight. Keep in mind that the weight you select will be the number of pounds subtracted from your pull-up — not the number of pounds you’ll be using. So for example, if you weigh 120 pounds and set the assisted pull-up machine to 40 pounds, you’ll be pulling up 80 pounds of your own body’s weight. 

Step onto the lower platforms and grab the handles above you. Place your knees onto the knee pad and slowly elongate your arms, lowering your body towards the floor. Engage your core and pull yourself back up to the starting position. Keep the spine neutral — don’t allow any excessive arching through the back. Continue for 10 to 12 repetitions

6. Rower

The rower is another machine that might not cross your mind for an abdominal-focused workout, however, rowers work the core very effectively — especially when it comes to building muscular endurance and stability. 

To use the rower, select an appropriate resistance. Sit down on the seat and place your feet into the foot pedals, tightening the straps until your feet are secure. Lean forward and grab the handles. Push back with your legs, keeping your arms straight in front of you. Once you’ve reached the end of your range, lean back slightly with an engaged core and bring the handles to your torso, just below your rib cage. Return to the starting position. Continue for 5 to 10 minutes, increasing your time as your endurance improves.

7. GHD Machine Sit Ups

Used one way, the GHD (or Glute Hamstring Development) machine strengthens muscles in the back of your body, like your glutes, hamstrings, and erector spinae (a muscle that runs the length of your spine). If you switch your orientation though, the GHD Machine can provide an intense challenge for your abdominals. Be forewarned that this is an advanced exercise — if you’re just starting out, save the GHD Machine sit-ups until you’ve strengthened your abdominals to the appropriate level.

To use the GHD machine for sit-ups, take a seat on the center pad with your hips hanging off slightly — your tailbone should hover over the floor. Place your feet into the foot pads. Engage your core and keep your spine neutral. Slowly lean back until your spine is parallel to the floor. Squeeze your abdominals and lift yourself back to the starting position. Be sure to keep the spine neutral — don’t allow the lower back to arch excessively. You can increase the difficulty of the exercise by leaning back further, allowing your spine to go beyond a parallel position to the floor. If you choose this variation, be sure that the lower back remains neutral with no excessive arching. 

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Jennifer Rizzuto

Jennifer Rizzuto is a freelance writer and certified personal trainer based in Long Island, NY. She covers various fitness-related topics and reviews for Tom's Guide. She also writes sketch comedy and short films, and performs frequently as an actor, singer, and improviser. When she's not writing, working out, or performing, you'll find her trying to convince her husband to get a dog.