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To Strengthen the Oblique Abdominal Muscles you Must Understand their Purpose

Written by: Nick Jack
Category: 2014
on 27 February 2020
Hits: 5795

Most of us at some point in our life have imagined having amazing washboard abs that we see covering the magazine covers. We have been convinced that to achieve this we must isolate the abdominal muscles with specific exercises to make it stronger and more toned. When it comes to training abs, or the core as it is commonly known, it seems like all knowledge, common sense, and logic on the subject of function is thrown out the window. What we are left with is exercises and methods that either do not work, or lead to severe injuries and pain. And the muscle that is often right in the firing line is the OBLIQUE abdominal muscles. There is no doubt the obliques are a very important part of the human body for controlling movement in the frontal plane and they provide some very unique movements that keep us free from injury and pain. They are also one of the most misunderstood and abused set of muscles and most people are not even aware that there is actually four of these muscles, as there is both internal and external oblique muscles. In this article we will explain why many of the beliefs, exercises, and program methods currently used for the oblique muscles may in fact be weakening you and exposing your body to potential injury. These muscles are not designed to function as other muscles and as a result should not be trained the same way.

Why Do People Try To Strengthen The Obliques?

If you walk into any gym or group training class you are likely to see many crazy versions of exercise used to target these muscles in the attempt to strengthen and tighten them up. But it is not limited to gyms and F-45 group classes for we also see these same abdominal exercises used in some Pilates classes and many rehabilitation programs for back pain in the belief that strong abs will heal the injury. 

There are two main reasons people will devote considerable time and effort with strengthening exercises of their abdominal muscles.

  1. To obtain a flat stomach and look good in a mirror
  2. They believe a strong core will prevent injury

Unfortunately isolating your abdominal muscles with endless versions of sit-ups and planks will not achieve either of those goals. The quote below sums this up perfectly.

Anyone with even the slightest knowledge in strength training will know it is impossible to spot reduce, yet this information seems to be ignored by the masses who still pound out hundreds of reps of abdominal exercises in the belief it will make their abs look better. You simply cannot out-exercise a bad diet.

And for the person who spends time doing heaps of abdominal work to prevent back pain or as an injury prevention method they misunderstand the true function of the core. We must realise that strength of the abdominal muscles WILL NOT change the faulty movement that leads to injury and pain. Your body will instantly sacrifice any strength if it only knows how to move with the same dysfunctional movement it has always used. You must identify and change the faulty movement patterns linked to the injury to have any chance.

Read the article why a strong core will not prevent back pain for more on this.

What Is The Function Of The Oblique Muscles?

Before we even discuss what exercises are best to use I feel it is important to be very clear on what the actual role of the abdominal muscles is and the unique characteristics of the obliques.

Stabilisation is the key function of the oblique muscles.

These muscles DO NOT have the capacity to move you on their own. They require the use of the more powerful and larger muscles of the arms and legs to do this. This means that they perform best when used in conjunction with these larger muscles that are trying to complete more integrated movements and the oblique muscles are activating to stabilise the body so you do not fall over. We have covered this in great detail and discussed the abuse of abdominal workouts previously in our article that I suggest to read – Are core workouts over-rated & causing more harm than good?

Where are these muscles located exactly? Firstly, there are 4 obliques, 2 external obliques (left and right side) and 2 internal obliques (left and right side).

The external oblique is the outside layer, the muscle you can see.  The muscle is attached from the anterior inferior chest (front / lower ribs), follow downward along the side of your body and finishes down on into the crest of the hip & groin ligament (front of the hip next to the abs).

They function unilaterally to laterally flex the trunk and rotate the trunk to the opposite side. They also are critical for spinal stabilisation which is vital for anyone with back pain. This is where they pull the chest downwards and compress the abdominal cavity, which increases the intra-abdominal pressure used in exercises like deadlifts. It also performs ipsilateral (same side) side-bending and contralateral (opposite side) rotation. So the right external oblique would side bend to the right and rotate to the left.

The internal oblique is the muscle underneath the external oblique, the muscle you can’t see. This muscle is just as important as the external oblique! This muscle starts from the anterior-lateral aspect of the hip bone & groin ligament (top of the groin & along the upper side of the hip), then branches up the body and attaches to the front of the ribs.

The internal oblique muscle functions similarly to the external oblique except it rotates ipsilaterally instead of contralaterally. It acts with the external oblique muscle of the opposite side to achieve this torsional movement of the trunk. For example, the right internal oblique and the left external oblique contract as the torso flexes and rotates to bring the left shoulder towards the right hip. For this reason, the internal obliques are referred to as "same-side rotators".

Now this is where people make their first big mistake when thinking of ways to improve the strength of the obliques by looking at these anatomical descriptions and basing exercises solely on the origin and insertion method. These muscles are not very strong and are heavily reliant on the more powerful muscles of the legs to instigate the movements of throwing a ball or swinging a golf club. To work the muscle separately from its partners does not guarantee it will work more effectively and can even cause serious injury usually to the lower back.  

Watch a video we filmed last week that quickly explains how the obliques work and gives you some simple exercise examples.

Twisting of the lumbar spine is very dangerous and is linked to many painful back injuries with the most common being a disc tear, but rotation of the thoracic spine and the hips IS NOT dangerous at all and is essential for efficient movement. This is where the poor choices of exercise can cause trouble as your body is forced to find rotation from the spine as the legs are disconnected from the movement.

In the article – Why you can never blame a single muscle for a movement problem we explained in great detail how the method of creating exercises based on this ruins the way we move for it ignores the way muscles interact with each other. Of all the muscles that are negatively influenced the most from isolation training it is the obliques! These exercises go against their true role of stability as they focus on flexing your trunk laterally or rotating your trunk. When you understand their purpose and see how they form a critical link between the upper body and the lower body during movements like walking or throwing a ball you will find the optimal exercises to enhance their strength and power. You will also come to appreciate that it is perfect timing is of more importance than pure strength for optimal function of these muscles.

All of this sounds very technical so let’s look at a few examples to explain this in more simple terms for you and give you a better understanding of how to effectively train them.

How the Obliques Provide Rotational Movement

The first thing people think of for movement using the obliques is twisting and rotational movement as seen in tennis, golf, or throwing a ball, and as a result many exercises are created to mimic this action. Unfortunately their choice of exercise is usually very poor and looks something like the picture above. Even worse is the speed at which it is performed which is often at slow speeds to try and fatigue the muscles and make them "burn". The problem is not with rotation or twisting but how it is done.

The twisting movement pattern is in fact one of 7 foundational patterns that we need to create movement for optimal function in life, so it is great to use exercises that will enhance this function. To understand how these patterns work we have provided you with a great FREE report you can download instantly with all of this explained for you in great detail. Click here to download.

When we perform trunk rotation movement, such as throwing a ball with your right arm, the left internal oblique pulls your trunk to the left and at the same time your right external oblique moves your trunk to that side also. The obliques do this movement explosively to help produce power, imagine the muscles squeezing together quickly for a split second twisting your trunk, this is the muscle working concentrically.

However, if you think it is only the obliques responsible for creating this movement you will be badly mistaken. This is where we see what is called the Anterior Oblique Sling being used for the first time and this is one of four myofascial slings we have to create movement. In all of these slings the obliques are the key muscle linking the upper body to the lower body and one side of the body to the other.

Watch the video below to see these slings in action and an example of the anterior sling exercise used to enhance throwing a ball.

The anterior oblique sling shows that the obliques help provide stability and mobility in the action of walking, running or in this case throwing a ball. Notice I said, “Helps”, as they do not perform this task on their own. This sling connects the obliques and the contra-lateral adductors to work in perfect sync to create a powerful spring-like movement. To strengthen the sling and enhance any movement that uses it requires it to be trained in the exact same position with the same timing. Strength and power can only be obtained if the timing between the legs and the torso is perfect.  You can begin to see how common exercises such as the side planks or lying medicine ball rotations will do little to improve this sling for their timing is not even close.

Read the article – How to strengthen the core via the slings for more detail on this.

We also have to consider how the obliques control rotation and actually prevent it. To prevent over-rotating after the ball is thrown your obliques must contract in the opposite direction much like applying the brakes. Without this you would lose all control of the throw and fall over to the ground. With most injuries this is where people are the weakest and need exercises to improve the ability to slow down and avoid injury. Shortly we will show you how to train for anti-rotation.

Next on the list is lateral flexion, and what we refer to as "anti-flexion".

Lateral Trunk Flexion, Anti-flexion, and Controlling The Frontal Plane

The lateral flexion movement is when your trunk leans over to one side. However, even though this is a movement the obliques can perform, it is often a movement it uses the obliques to resist. Repetitively flexing the trunk to one side can severely damage the discs of the spine which is an injury commonly seen with fast bowlers in cricket. This movement is not something we use often in life as it is very unstable and inefficient as we cannot use our hips or legs for good leverage. This brings us to where we see the body actually recruiting the obliques to avoid trunk flexion, and what we refer to as anti-flexion. Anti-flexion is something we use all the time without realising it and when it does not work correctly is when we are prone to injury or falling over. This is when we are moving in the frontal plane

A perfect example of this in action would be during exercises like single leg squats and also the suitcase carry which you can see in the two examples below.

This is where the obliques work to stabilize your spine from moving laterally during a walking action and utilizes what is known as the lateral sling. This sling connects the glute medius and glute minimus of the stance leg to the adductors and with the contralateral Quadratus Lumborum (QL).

Let’s say you pick up a heavy object in your right hand which now fires the oblique muscles in combination with the QL to provide a stable position for the pelvis to allow your leg to swing during walking. In this case the obliques are not trying to move you, instead they are trying to hold your pelvis stable so you walk efficiently.  

The suitcase carry and farmers walks for this reason are powerful oblique exercises which many people would not even consider to be an abdominal exercise. It is also why this exercise is a staple of many of the professional strongmen for the incredible strength gains it provides.

Read our detailed article – Farmers walks are the most under-rated functional movement

But it is not limited to strongmen as we see incredible benefits with using this exercise for correcting hip dysfunction causing walking problems. Using isolated glute and abdominal strengthening will do very little to change a walking dysfunction as it cannot change the motor program for walking which is now corrupted. The suitcase carry has a greater chance of correcting this for it is impossible to walk with a load while rocking side to side and is why we often refer to this as a self-correcting exercise. The body quickly learns it must stabilise the body in order to move and find the motion from the larger muscles like the glutes instead. The mistakes made during the exercise teach the body the correct timing and sequence of muscle firing.

Oblique Dysfunction Causing Lower Limb Injuries

The most concerning issue arising from dysfunction and poor stability is not just the area where the muscle is located but the risk of serious injury to areas further away from the body. This is where the core attracts a lot of attention for contributing to many chronic knee injuries like ITB friction syndrome or patella-femoral knee pain. The obliques are not the main cause but they can definitely contribute to the problem.

This is where weakness and dysfunction in a single leg stance and the frontal plane is exposed as a huge problem to your body when it attempts to move. Another great example of the obliques used as anti-rotators and anti-flexors is during a change of direction movement used in sports also known as cutting. One of the worst injuries to sustain in sports is an ACL tear which can be a season or even career ending injury. Up to 70% of ACL tears happen during a change of direction movement when the athlete plants their foot on the ground and attempts to rotate their body in relation to the planted foot. This creates a twisting force through the knee joint, which the ACL must absorb. When the ACL cannot cope with the force it ruptures.

The obliques are critical in preventing this injury for they must control what is known as “shoulder sway”, which is another way of saying anti-flexion and anti-rotation. This is a perfect example of how the obliques must slam the brakes on to prevent loss of balance and maintain optimal position for movement. It is not necessarily their strength that is of most importance but their timing. If they are too late to react the body will be forced to compensate.

Watch the videos below to see examples of this in action and exercises we use to teach the person how to prevent shoulder sway. Many people would not regard these exercises as training of the obliques but when you understand how important they are to executing this perfectly you begin to really understand their true function.

If you ever have ever witnessed an ACL tear you will often see the person demonstrating shoulder sway right at the point the knee goes. When you plant your foot quickly to change direction but do not control the upper body by recruiting good stiffness through the obliques, the shoulders will move you sideways to the direction you are moving. As a result, you will have too much of your body weight heading in one direction and it to change back the other way will not only be slower but risky as you will need to twist over your knee to get back! There is many reasons why this may happen but knowing to avoid this mistake will already make you more efficient.

For more detail on ACL injury prevention exercises read this article - 5 critical factors you need before returning to sport following knee surgery

Common Exercises for the Obliques

Now that you understand how the obliques actually work we will examine some of the common exercises and explain why many of these are not helping you but making you worse.

Dumbbell Lateral Flexion:

As we discussed earlier even though anatomically the obliques can perform this role, it actually tries to prevent it. Using an exercise to repeatedly flex the spine laterally is asking for trouble and this is definitely an exercise to avoid. The much more integrated version of the suitcase carry, single leg squat, or single leg deadlift exercises will achieve the goal you are looking for with this exercise but without the risk of injury to your discs.

I would also include the following exercises as something to avoid. 

  • Ankle taps
  • Cycle crunches

Lying Medicine Ball Twists:

While this does provide trunk rotation targeting the obliques it has three big problems.

  1. Firstly it removes the legs from providing the strength to move you which means there is an energy leak that will be made up for by the lower back.
  2. Secondly the spine will easily fall into flexion, and this combination of flexion with rotation is a perfect recipe for a lumbar disc bulge!
  3. Lastly the timing will be too slow. Again the lack of leg power results in everything being out of time and smaller muscles being forced to do the work of large muscles who are not involved.

A terrible exercise and one to avoid at all costs.

Side Plank:

This isolated exercise is one of the few isolated exercises that I don't mind as it can be a good choice for teaching your body to recruit the obliques as an anti-flexor. Its only drawback is it does not teach you how to integrate with the legs in a standing position. Always remember that timing is of more importance than strength when we discuss the obliques and this exercise does not require any timing.

My preferred choice is the easier version on the knees versus the more intense version on the toes, for it shares the hip movement used in deadlifts and squats. While it may not produce the stress on the obliques as the toe version it is more useful to changing the movement patterns used in a standing position.

Best EXERCISES for Strengthening the OBLIQUES

Now that we have covered some of the exercises to avoid what about the ones we should use? There are many exercises that I have left out here as the article would be far too long to include them all but below is a list of some of the most effective versions I like to use starting from easiest to hardest.

In-Line Kneeling Lunge

If I want someone to really feel how the obliques work as a reflex stabilising muscle in the frontal plane this exercise is the best. You will not feel any fatigue in the obliques at any point and you are not supposed to. What you will feel is terrible difficulty in remaining upright.

This features 3 levels of difficulty all requiring this reflex stability skill. The three levels are as follows.

1. Hands by your side
2. Hands behind your head
3. Hands behind your head and eyes closed

Each level forces greater reflex responses and for you to find a way to maintain optimal alignment and stability in order to move. Anyone with hip stiffness created by using the hips as the main driver of their stability will find this almost impossible. Why?

The hips can't remain still and simultaneously move. Something must be sacrificed and it will be your stability so that you can move your leg in front of you. This is such an amazing drill to use with any person who is a risk of falling, as it simulates the falling response but without the risk of serious injury. Trust me when I say the fear of falling is very much the same. This is a key exercise we use with beginners and older adults they begin training and is part of our assessment process.

Dr Stuart McGill’s Twisting Side Plank

This is a great exercise invented by Dr Stuart McGill and features in all of his books relating to back pain. The purpose of this exercise is to teach the abdominal muscles to create a torsional stiffness during rotational movement and prevent the spine from twisting and the hips from compensating. As opposed to the traditional plank exercise that emphasises holding for long periods of time this movement is more concerned how you maintain stability to move. A fantastic exercise for learning how to stabilise effectively first before you move. This is a perfect introduction to the more integrated and complex exercises to come.

This is a lot harder than it appears and many people struggle to get this right when they first try it.

Cable Wood-chop:

All the wood-chop variations are great exercises to develop trunk rotation movement for the obliques. The most critical part of this movement is the weight shift used by the legs as it teaches the obliques to work in conjunction with the whole body. The legs are where your power comes from and the obliques are there to assist the movement and to apply the brakes at the end. Problems arise in this exercise when the legs are not used, the load is too great, or the timing is too slow. These movements require a fast timing for it to work efficiently.

Medicine Balls & Sledgehammer Variations

These exercises are the more advanced versions of the cable wood-chops and require a much more explosive timing. Most people tell me they don’t feel their obliques when doing this movement, they feel exhausted and out of breath instead. This demonstrates they are doing the exercise correctly for the obliques should not feel fatigued at any point. If they do it means you are moving far too slow and placing stress onto muscles in a movement they should not feel anything. Timing is everything.

Single Cable Push:

We discussed this movement earlier when we looked at the slings. This is an excellent version for strengthening the anterior sling and can be used by people of all ages and abilities. To see a detailed explanation of all the benefits of this exercise read the article – Why the single cable push is much more than a chest exercise

Turkish Get Ups & Suitcase Carry:

Both of these exercises are very similar and both are primarily concerned with stabilisation through anti-lateral flexion & anti-rotation! They are both self-correcting exercises that force you to find a way to remain stable or you cannot do the movement. The best part is these exercises mimic many day to day tasks and as a result significantly change the way we move! I would regard the Turkish Get up as the ultimate core exercise and here is why.

  • Greatly improves shoulder stability and thoracic mobility at the same time!
  • Improves overall body stability and integration between upper and lower body
  • Promotes reflexive stability of the torso
  • Encourages great mobility of the hips and thoracic spine, the two areas most people are lacking
  • Improves the body's ability to coordinate and enhance balance from lying to standing
  • Develops upper body strength, trunks strength, and glute strength

I often like to use a workout that uses the Turkish Get Up and Farmers Walks in between sets of other exercises to improve my overall stability and functional movement.

Below is a video example of this.

Advanced Programs for Knee Pain and Back Pain

Throughout the article I only briefly discussed the use of specific programs for injury and especially for knee pain and back pain. If you are currently suffering with an injury in these areas of the body you will find our specific programs for these injuries invaluable. These programs include easy to follow step by step instructions for assessing and correcting your problem at the source.

Click the image below of the program you require to find out more.



I hope this article provides you with a better understanding of how the oblique muscles truly function and the best exercise choices and methods you can use to develop incredible core power. We must appreciated that the abdominal muscles are designed differently to other muscles and as a result must be trained differently.

Always remember to use fast timing with rotation starting with the simple exercises first before progressing to the more powerful and explosive versions. Single leg squats, single leg deadlifts, Turkish get-ups, and suitcase carries are all excellent examples of oblique strengthening exercises that develop your ability to resist rotation and flexion. Not only do they provide strength they improve how you move for life ensuring you remain injury free and able to do all the things you want to do without pain or limitation. And of course this will help you to achieve incredible levels of fitness which will go a long way to having the flat stomach (as long as you are eating well) that so many desire.

If you live in Melbourne and would like to know more about our personal training or core strength programs click the image below to request a free consultation and I will get back to you within 24 hours to schedule time.

About The Author

Nick Jack is owner of No Regrets Personal Training and has over 15 years’ experience as a qualified Personal Trainer, Level 2 Rehabilitation trainer, CHEK practitioner, and Level 2 Sports conditioning Coach. Based in Melbourne Australia he specializes in providing solutions to injury and health problems for people of all ages using the latest methods of assessing movement and corrective exercise.


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