Bird Dog vs Back Extension: which is the best exercise for lower back pain

Jun 18, 2021

When it comes to exercises for lower back pain, there are plenty to choose from, but how do you know which ones are right for you?

Some exercises can help lower back pain and some can hinder it, it all depends on your situation, but arming yourself with information about how each exercise works anatomically is a great place to start in working out which will be most effective.

Why are some exercises better than others for low back pain

Different exercises will require your body to undertake distinct movements, each bringing different muscles into play and exerting force on your spine and other joints. This can be in the form of compression, over extension or ineffective working of the muscles. To get the most out of any exercise you perform, your goal should be to maximise muscular activity while reducing the risk of further injury.

In this tutorial we’ve chosen to compare the Bird Dog and the Back Extensions, two commonly selected exercises for lower back strength and rehabilitation, to help you make an informed decision about which is right for you. 

Compression around the spine

The spinal erectors are a group of muscles that run up the back of the body along either side of the vertebral column, from your hips to the base of your skull. They support your spine to bend to the side and extend backwards as well as rotate and they’re larger and thicker at the bottom end – this section of which is often referred to as your lumbar muscles.

When you bend or overextend, you bring these muscles online and they begin to exert a force on the spine. In fact, when you perform a back extension, whether on the floor or on a machine, you will be creating 4,000-6,000N or Newtons of compression on your spine.

You can imagine this if you think about squeezing a sponge with one hand. Your hand represents the spinal erectors acting on the sponge (spine).

The difference with the Bird Dog is that it creates only half as much force, 2,000-3,000N

Why? Because when you go down on all fours to perform the Bird Dog, lifting only one leg / arm combination at a time, you’re activating the muscles on only one side of the body meaning the compression effect is halved.

So if you harbour a weakness in your lower back and it can’t tolerate a great load or compression, the Bird Dog will be a better option than the Back Extension, to minimise this force.

You’ll find diagrams explaining this further in the video above.

Extension of the spine

But compression isn’t the only thing we need to take into account. When you perform a Back Extension, the spine is forced backwards into an exaggerated arch which can impact on your vertebrae.

Again, there are diagrams in the video, but in summary each segment of your spine is made up of two vertebrae connected by a facet joint, with a fluid-filled disc or ‘shock absorber’ situated between then. As the spine is pushed to overextend, the backs of the vertebrae will be forced together, squeezing the disc and potentially bruising the nerve, impacting the joints and causing long term effects when the exercise is repeated over time.

Further, repetitive movements that involve back bending can actually cause stress fractures in the bones of the lower spine, known as Pars Defects. This may be an extreme example and is unlikely to impact everyone who does Back Extensions, but if you have a predisposition to this, you’ll certainly see problems over time.

By comparison, the Bird Dog allows for a more neutral posture, minimising extension of the spine.

How the muscles work in these two exercises

It’s important to understand the muscles that you’re activating during lower back exercises. Back extensions utilise body building principles of focusing on one area at a time, working the muscles – in this case the spinal erectors - hard and repeatedly.

When we look at where these muscles are positioned, up the length of the back, and consider the way we’re making them move during a Back Extension, we’re actually exerting force at the top of the back, or top of the muscle, in order to isolate and tighten the part of the muscle at the bottom. By trying to raise the upper back, we’re not using the long muscles effectively as we’re working the muscles from the wrong end. This will need a huge amount of strength and force for little benefit.

McGill explains it as, “exercises to isolate the lumbar muscles [by doing back extensions on a machine or on the floor or even back strengtheners] cannot be justified anatomically or from a motor control perspective because all the players in the orchestra must be challenged.”

Put simply, Back Extensions don’t bring enough muscles into play to be truly effective. 

Compare this to what happens muscle-wise with the Bird Dog.

With the Bird Dog, you’ll achieve glute activation as well as the erector spinae thoracic muscles creating stability through the lumbar spine. You’ll benefit from the neutral posture so the facet joints, the lumbar and the spine aren’t becoming irritated. By lifting the arm and screwing the shoulder down into the rib cage you’ll also activate muscles like the latissimus dorsi and the obliques, and by bracing the abdominal wall the rectus abdominus too. Done correctly, you’ll even bring online aspects of the posterior deltoid, rhomboid and trapezius – multiple players in the ‘orchestra’.

Using the Bird Dog all of these muscles are working together to stabilise the spine and doing it in a way that reduces compression because it’s done on one side at a time.

The Bird Dog reduces risk of further injury while maximising muscular activity and getting the muscles to work together to rehabilitate the spine in a much more effective way. And learning and understanding more about the impact of specific exercises on your body can help you make a better and more informed decision about exercising for your lower back pain.

Want to know more about exercising the right way for low back pain rehabilitation? Choose one of the links below:

To enrol in my How to Overcome Low Back Pain Online Coaching click here


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