If you’ve ever done a Pilates class, rehab exercise or core workout, there’s a good chance you’ve heard some version of this cue:
“Squash your lower back into the floor.”
So, should you?
Like most things when it comes to movement, the answer is: it depends.
Flattening your lower back isn’t inherently bad. A gentle posterior pelvic tilt can be a really useful way to teach someone how to find their abdominals, understand the relationship between their rib cage and pelvis, or regress an exercise they’re not yet strong enough to control.
Where I think we run into problems is when people start believing that a flat lower back equals an engaged core.
Because ultimately, that’s not what I want you to be good at.
I want you to be able to maintain a strong, controlled trunk while your arms and legs move around it and, in many situations, that means being able to maintain the natural curves of your spine.
Your spine isn’t designed to be perfectly straight.
The lumbar spine naturally has a degree of lordosis, or an inward curve through the lower back. When we talk about finding a “neutral spine”, we’re generally not talking about forcing the back completely flat.
We’re looking for a comfortable position where the rib cage and pelvis are well organised, the natural lumbar curve is maintained, and you can create abdominal tension without excessively arching, tucking or holding your breath.
This becomes particularly important as we progress core exercises.
If I have someone performing a dead bug, for example, I’m less interested in whether they can aggressively press their back into the floor and more interested in what happens when they extend their leg.
Can they keep their pelvis relatively still?
Can they stop their ribs from flaring?
Can they maintain their lumbar position?
Can they continue breathing while creating tension?
That tells me much more about their ability to control their trunk.
Again, there are situations where flattening the back is completely appropriate. The problem is turning it into a blanket rule for core training.
If your strategy is always to push your lower back as hard as possible into the floor, you can end up relying on a large posterior pelvic tilt to create the feeling of “core engagement”.
You might feel your abs working but that doesn’t necessarily mean you’re developing the control we’re actually looking for.
It can also encourage people to brace excessively and hold their breath. Instead of learning how to create pressure through the entire abdominal wall while continuing to breathe, core training becomes a competition to tense everything as hard as possible.
Perhaps most importantly, it doesn’t always transfer particularly well to what we actually need our core to do.
Think about squatting, deadlifting, carrying something heavy, pressing overhead, running or simply moving through everyday life.
There isn’t a floor underneath you to squash your back into.
Your trunk needs to create stiffness and manage force while maintaining an appropriate spinal position as the rest of your body moves around it.
That is a skill worth training.
If you’ve always been taught to flatten your back during floor-based core exercises, try these instead.
Lie on your back with your knees bent and feet on the floor.
Rather than deliberately arching or flattening your back, allow your pelvis to settle somewhere comfortable.
There will usually be a small amount of space underneath your lumbar spine.
That’s okay.
The goal isn’t to create the biggest arch possible. We’re simply recognising that your spine has natural curves and we don’t automatically need to eliminate them before starting an exercise.
Now think about the relationship between your rib cage and pelvis.
Take a breath in, allowing expansion through the front, sides and back of your trunk. As you exhale, feel your abdominal wall create tension around your midsection without aggressively pushing your back into the floor.
I often describe this as creating 360-degree tension. Think about drawing your hip bones together.
You want your trunk to feel strong and supported without your ribs dramatically flaring, your pelvis tipping forward or everything being squeezed as hard as possible.
This is probably the most important one.
If you’re performing a dead bug and your lower back starts arching further away from the floor as your leg extends, you’ve probably exceeded the range you can currently control.
The answer isn’t necessarily to smash your back down harder.
Shorten the movement.
Bring the leg back slightly and find the point where you can maintain the same lumbar and pelvic position.
That might mean tapping your heel closer to your body. It might mean keeping your knee bent. It might mean moving one limb rather than two.
Your range of motion should be dictated by your ability to control it.
Then, as your core gets stronger, you can progressively increase the challenge.
There’s another important piece of this conversation.
I don’t believe your spine should always remain neutral.
Your spine is designed to move. We want the capacity to flex, extend and rotate, as well as the ability to resist those movements when a task requires stability.
Good core training should eventually expose you to different positions, directions and loads.
So this isn’t about replacing one rigid rule “always flatten your back” with another rigid rule — “your spine must always be neutral.”
It’s about understanding the purpose of the exercise.
Sometimes I want movement through the spine.
Sometimes I want a posterior pelvic tilt.
Sometimes I want you to maintain neutral and resist movement.
The exercise, the individual and the outcome we’re chasing should determine the strategy.
If flattening your lower back helps you initially understand how to control your pelvis or engage your abdominal wall, great. It can be a useful tool.
But it shouldn’t necessarily be the end goal.
As you become stronger, I want you to develop the ability to maintain your natural lumbar curve, organise your rib cage and pelvis, create 360-degree abdominal tension and then challenge that position by moving your arms and legs.
I don’t just want you to be good at squashing your back into the floor.
I want you to be good at controlling your spine when the floor is no longer there to help you.
And that is a much more useful definition of a strong core.
Ange Drake is a personal trainer, women’s empowerment coach and fitness blogger in the northern suburbs of Melbourne. She is the director of one of the few womens’ only strength training gyms in Melbourne, 23W. Ange helps women to learn how to use strength based training, nutritional strategies and a positive mindset to transform their bodies, relationship with food and mind.
