Single Arm Decline Crunch

Abs, the cornerstone of strength. The core is perhaps one of the most integral parts of the body that controls upper and lower body strength and ability. With a weak core, both the lower and upper parts of your body will not fire to their fullest potential. Here is a quick guide to rocking the single arm decline crunch, an essential core exercise

The benefits

Troy doing a single arm decline crunch at the gym

Single arm decline crunches are one of those exercises that work out several parts of the body at once, targeting more than one muscle group for an overall excellent workout. The back, chest, and hip flexors are all strengthened as you lift into the crunch. 

The group work that your muscles go through is vital for improving balance and stability. Your posture will improve, as well as pre-existing lower back pain. What more can you ask for in an exercise? 

Muscles Targeted

Troy Adashun showing off his lower abs

Crunches are quite popular, especially with women, but what happens once you have aced the crunch and want to improve? How do you build that six-pack? The single-arm decline crunch is an excellent exercise, the mechanics focus on isolation and work on the six-pack muscles:

  • External obliques
  • Rectus abdominis
  • Rectus femoris

The secondary focus is on the hip flexors, back, chest and shoulders.

Single arm decline crunch Execution

Mechanics: Isolation

Force: Push

Aim: 2 sets of 12-15 reps on each side.

How to crunch like a pro:

  1. 1
    Set the decline to a 45-degree angle. Get set up, sit on the bench.
  2. 2
    Grip a dumbbell or a kettlebell in a neutral grip - palms facing inwards.
  3. 3
    Place your arm directly over the lower chest.
  4. 4
    Engage your core and abdominals. Using them to lift your torso off the bench.
  5. 5
    Drive your arm straight up as if you are being pulled up through your arm, squeezing your core together. Push your arm to as high as it can go. Remember to keep your lower back down on the bench; it's a crunch, not a sit-up!
  6. 6
    Once you are fully extended, hold for a few seconds.
  7. 7
    Slowly lower back down. Your shoulders need to touch the bench after each crunch.
  8. 8
    You have completed 1 rep. Repeat for 12 - 15 reps.
  9. 9
    Switch arms and perform 12 - 15 reps.
  10. 10
    Repeat 2 sets per side.

Tip: Your body shouldn't rock or swing between positions. Engage your core and feel the burn when you know you are getting the best out of the exercise. 


While the single arm decline crunch is great for a fitness fundi with an intermediate fitness level, a few variations suit different fitness levels. 

Double weight crunch

Troy's hands on dumbbells on the rack

Are you looking for more of a challenge? Try this. Instead of using a single weight, use one in each hand. Be sure to adjust your position slightly. Practice a few times to get the hang of both arms above you, with a somewhat lighter weight. 

Drive both arms up with your torso, pause and squeeze the abs as you reach the top. Release and lower back down slowly

Vertical weight plate press

Troy doing a plate crunch

This is a variation of the one arm decline crunch you can do with no heavy equipment or when you're traveling and don't have access to your gym. 

Force: Push 

Aim: 2 - 3 sets of 10 - 15 reps

Targets: The entire core 

  1. 1
    Sit flat on a mat. Hold a weight plate in both hands.
  2. 2
    Lie back on the mat with the weight on your chest.
  3. 3
    Position your hips and bend the knees at a 90-degree angle—feet off the floor.
  4. 4
    Inhale, and as you exhale, push upwards. Engage your core and lift your torso as you push the weight away from your chest.
  5. 5
    The weight should be extended directly above your chest.
  6. 6
    Slowly lower back to start.
  7. 7
    Repeat 3 sets of 10 - 15 reps.

Dumbbells or kettlebells

colorful kettlebells in a row in a gym

If you don't have a dumbbell on hand or would like a little more stability, use a kettlebell instead. This is also great for a double-handed crunch as you can stabilize one weight instead of two at a time.

Alternatively, a double-handed crunch with a lighter weight can offer more stability for a beginner. Grip the kettlebell firmly with both hands, allow the kettlebell to rest on the tops of your hands. 

Add these exercises for killer abs

Like macaroni goes well with cheese, these go hand in hand with crunches. If you are following a PPL split, be sure to pair the right exercises with each other. 

Captain's chair leg raises

man exercising on bars

The Captain's chair is perhaps intimidating to the uninitiated. This isolation exercise truly builds core strength and teaches you control over your abdominals. 

The Captain's chair leg raise should not be performed with the use of momentum. The aim is to lift with your core and not by the momentum built by the motion of swinging your legs up.

Plank with dips

a young man performs a plank exercise in a lower ab workout

The plank, it's enough to humble any gym bunny. The plank engages every muscle in the core—these work on creating definitions across the abdominals. Adding dips in, you work the glutes and obliques to a larger extent. 

The plank is a supportive exercise that helps build strength, so you end up lifting heavier, seeing improved performance in explosive sports and stability. It also helps build strong, aesthetic glutes.

Mountain climbers

young woman with pink hair doing the plank hop exercise

Sculpting is much easier when you strip away some of the fat that sits above your muscles. Superset your decline crunches with a set of mountain climbers between sets for the ultimate fat burning.

What are you waiting for? Get on that decline bench!

A strong core is the cornerstone of overall health and fitness. With a weak core, the rest of your training will suffer. Women in particular benefit from a strong core routine as pregnancies and birth disrupt core strength.  

As your core improves, the rest of your workouts will improve with it. You will start seeing better results in every other aspect of your health, life, and gym performance. 

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