If you trying to achieve a muscular and defined abdominal region, introducing oblique crunches or side crunches as they are also referred into your ab routine is a must.

Having strong obliques give your body that desired athletic look, as well as supporting your overall posture, enhancing sporting performance and aiding the execution of more complex compound movements.

In this article you will learn:

  • What are oblique crunches?
  • How to do oblique crunches?
  • Oblique crunch variations
  • Advanced Oblique crunches
  • Oblique crunch benefits

What are oblique muscles?

The obliques consist of both internal and external obliques and are responsible for the twisting of your trunk and provides support to your spinal column when moving and stabilises your core.

oblique crunches muscles worked image

Before we jump into how to do oblique crunches, why not go and check out our range of personal trainer qualifications and courses and start a career about something you’re truly passionate about or download our latest prospectus here.

Right, let’s jump straight in….

What are oblique crunches?

The oblique crunch exercise is traditionally a bodyweight movement that works both the internal and external obliques through rotation and torque by lifting or “crunching” your upper body towards your lower body or vice versa.

How to do Oblique Crunches?

Firstly, there are several variations on how to do the oblique crunch exercise on the floor and methods utilising equipment. We will show you variations and progressive forms of the exercise that you can strive for or include in your next oblique crunches workout.

Let’s start with the most recreational way most gym-goers perform the oblique crunch:

Oblique Crunch (Side Crunch)

Set-up: You just need an exercise mat or a soft floor to perform this exercise on.

Starting Position:

  • Lie down on the floor or mat in a conventional sit-up position with legs at roughly a 90-degree angle and foot planted on the ground. Do not let your feet come up during this exercise.
  • Place your hands behind your head on either side to support your neck through the movement and keep your elbows pointing out.
  • Do not pull your head forward and keep your chin off your chest when performing the side crunch.

how to do oblique crunches image


  • Take a big breath in and engage your core.
  • Lift your right shoulder blade off the floor and then drive your elbow in the direction of your left knee.
  • Remembering to keep your chin off your chest and not pulling your head and neck.
  • Squeeze at the top of the movement and then slowly release back to the starting position. Remember that you are driving across your body, not up and across, that is a sit-up with a twist, not a crunch.
  • Repeat the movement until the desired number of repetitions have been completed and the repeat on the other side.

oblique crunch each side image

Oblique Crunches (Each Side)

If you prefer to focus on each side of your obliques alternately, much like you might with dumbbell bicep curls, then you adapt the exercise above using the following steps.

Starting Position:

  • Set-up and get into position in the exact same manners as the single side oblique crunch with your back on the floor and feet firmly planted at a 90-degree angle.


  • Again, take a breath, engage your core and lift your right shoulder blade of the floor and drive your elbow in the direction of your left knee.
  • Once you have returned slowly and in a controlled manner back to the starting position following the same angle of rotation back, repeat the movement lifting your left shoulder blade and driving towards your elbow towards your right knee.
  • Remember to breathe out as you’re contracting and to control the motion on the way back to the starting position.

Oblique Crossover Crunch

Another side ab crunch is the oblique crossover crunch. Many gym-goers opt to cross their leg over, hence the name, to give them more of a directional motivation when executing the movement. This exercise does not really possess any greater benefit or progression than the side crunches mentioned above.

Starting Position: 

  • To start the oblique cross-over crunch, lie flat on your back with your body facing the ceiling.
  • Cross your left leg over your right thigh
  • Rest your right hand on the side of your right temple or side of the back of your head.
  • Rest your left hand on the middle of your stomach (this is to remind you to contract and feel your stomach as your crunch up)


  • Tense your abs and crunch over (not up and over) and across your body so that your right elbow touches the inner left knee (exhale your breath as you do this)
  • Once your elbow and knee make contact, pause in the top position for one second and squeeze your abs as hard as possible
  • As with all oblique floor crunches, slowly lower yourself back down (whilst inhaling)
  • Return to the starting position
  • Repeat for the desired number of repetitions before switching sides.

Oblique Side Crunch each side image

Image Credit: Nick, Founder of LEP Fitness.


Lying oblique crunches

Another floor oblique crunch is the “lying side crunch” or the “lying oblique crunch” as its sometimes known. This variation isolates the obliques your trying to target more than the above variations and is considered by many trainers as safer for your spine and more controlled as it’s a lateral movement as opposed to a vertical one.

Set-Up: You just need an exercise mat or soft floor to perform this exercise.

Starting Position: 

  • Lie down on your left-hand side with both knees bent at roughly a 45-90-degree angle to your body for support.
  • Place your right hand on the right side of your temple.
  • Rest your left arm on the floor and keep it straight and relaxed.
  • Engage the right-hand side of your core and you’re ready to start the movement.

oblique twist crunches image


  • To complete this side crunch exercise, contract the right side of your abdominals whilst bringing your elbow towards your outer thigh.
  • As you contract up, slowly exhale.
  • Pause in the top position, and contract your abs as hard as you can, hold the contraction for one second before slowly lowering back to the starting position, inhaling your breath on the way down
  • Once you’ve completed a repetition, repeat for the desired number of repetitions and then switch sides.

how to do oblique crunches exercise image


Lying Oblique Side Crunch with leg over

This floor oblique crunch is a good alternative exercise if you struggle to maintain keeping your legs relaxed and feet planted on the floor when performing a conventional oblique crunch.


Starting Position: 

  • Lie down on your mat with your back on the floor with legs extended
  • Whilst keeping your upper body and head fixed, lift your right leg up and extend all the way over your left leg as far as you can go to give yourself a wide base of support
  • Place your left hand on your thigh for support and to help sustain your position.
  • Place your right hand behind the right-hand side of the back of your head.

floor oblique crunches images


  • Whilst maintaining a neutral spine, keeping your core tight and focusing on a point on the ceiling, drive upwards, lifting your right shoulder blade and trap off the floor (do not curl over).
  • Remember to exhale when you contract and inhale during the controlled lowering phase of the exercise.
  • Repeat this movement for the desired number of repetitions before switching sides.

leg over crunch image

Standing Cable Oblique Crunch

The standing oblique cable crunch is a nice variation to include in your oblique workout and a good way to increase the levels of resistance than oblique bodyweight exercises. This exercise is all about form and technique and needs to be practised to gain full benefit from. It can act as part of a superset or as the weight can easily be changed as a drop set.


For the oblique cable side crunch, you will need a high cable machine. Set it up as per the instructions and decide which weight you are going to use. We suggest building the weight up incrementally rather than starting on your maximum pull. That way you can avoid injury ad focus on form.

Starting position:

  • Grip the handle with your dominant hand and face your body at a right angle to the pulley.
  • Keep your feet firmly on the floor and shoulder-width apart.
  • Your forearm should be at a right angle to your upper arm.
  • Engage your abs, and for extra intensity squeeze your shoulder muscles.

low cable oblique crunches image


  • Pull straight down on the weight using your obliques. Ensure you do not go too low.
  • When you get to the optimum point for you, which is usually towards the hip where you feel the pressure within the abs, pause for a second.
  • Then bring your arm back up in a controlled manner to the starting position.
  • Exhale on the pull, inhale on the raise.
  • Carry out your reps on one side of your body and then switch sides. Alternately, you can complete these side oblique crunches in an alternative format if you wish, but ensure you sustain control when switching between sides.

oblique twist crunches image

Progressive oblique crunches

Once you have learnt how to do the oblique crunches mentioned above, start moving onto more complex oblique crunch exercises like the ones below that will challenge your core more increase more muscle fibre activation and ultimately get you better results in the long run.

Stability ball side Crunch

Once you have mastered some of the floor oblique crunches, a form of progression would be to attempt the stability ball side crunch, which places a higher demand on your core and stabiliser muscles to remain in position and execute the movement.

Set-up: For this side crunch exercise, you will need a stability ball and you can start off by setting yourself near a wall with a little leg room on one side.

Starting position:

  • To get into the starting position, place the stability ball a few feet away from the wall and place your left hip on the ball.
  • Extend your legs out for support with your right leg fully extended and your foot facing forward at a 90-degree angle flat on the floor.
  • Your left leg should be back to increase your base of support and not fully planted.
  • Place your right hand either fully out or behind your head and place your left hand on the swiss ball for extra support.

Oblique crunches on a stability ball Execution:

  • To execute swiss ball oblique crunches, lift your body off the ball in a straight line over your hip.
  • Ensure to keep a neutral spine, your head facing forward and do not let your shoulders rotate.
  • Breathe out as your contract and then take a big breath in as your lower in a controlled manner back to the starting position.

To make this stability ball oblique crunch harder, you can move your hips further up the ball and then extend your arms out so when you lower your body your fingertips can almost touch the floor. This will increase the range of motion and challenge your obliques and core muscles even further.

Decline Oblique Crunches

Decline bench oblique crunches increase the range of motion by comparison to oblique crunches on the floor, as your body goes through a larger range of motion and thus your obliques are under more stress and tension.


This exercise is usually performed at the gym because it needs an exercise bench and most preferably a decline bench. If you have an exercise bench at home, however, you will be able to this side crunch exercise without leaving the house. Make sure you have the bench set at a decline angle that you feel comfortable with. You can start with a slight decline and progress to steeper angles once you have adapted to the exercise.

Starting Position:

  • The starting position for the decline twisting crunch is to slowly lower your back on the bench, ensuring that you keep your back flat against the bench.
  • Wrap your feet around the supports underneath to stop yourself from slipping. You might be able to hook your toes behind the bar underneath, depending on how secure you feel.
  • You are now in the starting position for the decline oblique crunch and are ready to begin.


  • To execute, lift your right shoulder blade off the bench and then drive your right elbow in the direction of your left knee.
  • Remember, you are not curling up, you’re curling across your body.
  • You can put your hands behind your head as you do with other crunches or place one hand on your hip if you prefer. Do not utilise them to pull yourself upwards, they are there to prevent you from using your arms to create momentum.
  • Once you have pulled yourself up and over, squeeze for a brief moment before controlling the eccentric contraction back to the starting position.
  • Allow your body to fully extend at the bottom of the movement before attempting another repetition and remember to breathe throughout the movement.
  • Complete these decline bench oblique crunches each side at a time or rotate sides in between repetitions.

Decline side crunches are difficult; however, you can make them even harder by extending your arms out in a straight line, above your head to shift your centre of gravity further away from your point of axis. Alternately, you can simply add weight in the form of plate or medicine ball by placing it on the side of your chest you’re crunching and then progressing to placing it in your hands that are extended above your head.

Reverse Oblique Crunch

The reverse oblique crunch really works the exterior obliques and creates huge levels of tension on your abdominals that other crunches on this list do not. This exercise can be incorporated into your oblique crunch workout in two ways. Firstly, it can be performed with knees bent or to make the movement harder, with legs fully extended.

Bent Leg Reverse Oblique Crunch:

Starting Position:

  • Lye down on the floor with your arms down by your side and your knees bent at roughly a 90-degree angle and feet together. If you feel more comfortable you can place your arms out wide to increase your base of support.

floor oblique crunch image


  • Take a big breath in and engage your core.
  • Lift your legs off the floor whilst ensuring there is no rotation in your head, torso or shoulders and drive your right near in the direction of your left shoulder.
  • Squeeze at the top of the movement exhale as you contract your obliques.
  • Slowly lower your legs back down to the starting position but ensure your feet do not touch the floor before repeating the next repetition to maximise tension on the muscles.
  • You can complete the reverse oblique crunch on one side or alternate between repetitions.

oblique crunches each side image

If you want to make the reverse oblique crunch more challenging, try extending your legs out like the video below:


Hanging Knee Raise Oblique Crunch

Saving the hardest until last, the hanging knee raise oblique crunch is an advanced movement for seasoned trainers that works the obliques, hip flexors and abdomen all in one movement.


For this exercise, you will need a bar that is the correct height for you. It must be above you head and able to support your total weight, including being stable enough so that when you raise your legs off the floor it will remain in place and not flex. A chin-up bar works fine.

Starting Position:

  • Stand directly beneath the bar so that it is positioned high above your head.
  • Jump up, grip the bar overhand to give yourself more stability, with your hands in line with your shoulders. Hang with your feet facing forward.
  • Take a big breath in and engage your abdominals and focus on preparing for your first raise.


  • Raise your legs out in front of you and bend your knees at a 90-degree angle with legs together and toes pointed.
  • Pull your knees up and across to one side of your body, allowing your hips to rotate until your toes are perpendicular to the floor.
  • Aim to move knees up so that your knees almost touch your chest and squeeze at the top of the movement. Whist crunching exhale.
  • When you lower your legs do not straighten them. Inhale on the release, keep your legs bent at the knee and complete as many reps as you can. The hanging oblique knee raise can be completed by doing reps on one side and then repeating or by carefully switching sides after each repetition.

hanging oblique crunch image

Oblique Crunch Benefits

Oblique Crunch Benefits image

Performing oblique crunches regularly as part of your abdominal workout will help improve your overall posture, balance when playing sports with rotation such as swimming, baseball or cricket, as well as enhancing your overall flexibility.

A major oblique crunch benefit is that it fully engages and strengthens the entire abdominal wall and the lower back which supports your spine. It will activate your stabiliser muscles which are critical in more functional compound movements and reduces the risk of injury.

It’s also beneficial in aiding everyday tasks such as carrying a bag of shopping or twisting to grab the toilet roll.

Side Crunches: Reps & Rest Gaps

This entirely varies depending on your fitness goals. Are you looking to build strength, tone or muscular size? See the general guidelines below to getting reps, sets and rest gaps right for your fitness goal:

Tone (Muscular Endurance):

Reps: 12-20

Rest: 30 – 45 Seconds (short)

Muscular Size (sarcoplasmic hypertrophy):

Reps: 8-12

Rest: 60-90 seconds

Before You Go!

Before you go and put these side ab crunches into practice, go check out OriGym’s recognised personal training diploma or our online sports nutrition course. Thanks to Nick, head trainer and founder at LEP Fitness for contributing towards this post.

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About the Author: Luke Hughes

luke hughes origym authour
Luke is the Co-Founder of OriGym. Holding a first-class degree in Sport and Exercise and an MSc in Sport and Nutrition, he is also qualified as a Level 4 Personal Trainer with various specialist credentials covering the entire spectrum of health, fitness and business. Luke has contributed to a variety of major industry publications, including Men’s Health, Women’s Health, Daily Telegraph, The Guardian, Metro, Cosmopolitan, The Mirror, The Sun, The Standard and more.

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