Should you lift with a flat back or a neutral spine?

Hey there fitness pals! So, we've all heard the mantra "keep your spine straight when lifting", right? The idea is to keep our back in a 'neutral' position to avoid those pesky shear forces that can lead to injuries when lifting. Sounds simple enough, but wait, there's more to the story, particularly when it comes to managing these forces during lifting. Buckle up, as we're going for a deep dive!

First things first, let's clear up the term 'shear.' Imagine you're lifting something heavy. There's a force acting on your spine, let's call it the 'master force'. We can break this master force into smaller forces - the compressive and shear forces. Now, compressive force is like an elephant sitting on your spine - it pushes down. Shear force, on the other hand, tries to slide your spine sideways. Both of these can potentially lead to tissue damage.

Now, imagine bending forward while lifting something. Thanks to gravity, your body wants to fall forward, creating an anterior shear force that your spine has to resist to avoid injury. The more you lean forward (assuming the weight is the same), the more your spine has to fight against these forces.

Interestingly, our spines can handle more compressive force (like the elephant) than shear force before things start to break down. This makes sense because when we lift, the compressive forces are usually bigger than the shear forces. But this could be a bit tricky when we prescribe exercises like deadlifts where the shear forces can get really high, almost reaching the spine's structural limits. That's why we recommend adjusting your lifting technique to control these forces.

We're usually told to keep a 'lordotic' or neutral spine when lifting to minimize this forward force. But recent research suggests that lifting with a slightly more rounded back might actually reduce these forces, especially at the lower back where they're highest during lifting.

Also, our back muscles, the erector spinae, act differently at different levels of the back. In the middle, they can create a force that pushes the spine back (L5/S1), but at the lower end, they actually increase the forward force, adding more load to the joints.

So, the idea of avoiding rounding the back during lifting to reduce these forward forces doesn't seem to hold up. In fact, a bit of rounding could actually be a smart strategy to reduce these forces at the lower back, and we might want to coach for a more flat back instead.

My take? During heavy or fatiguing lifts, having a "flexion moment" (a well-controlled, momentary rounding of the back) could be a good way to build up our body's tolerance. Technique is important in a deadlift, but these moments can help us learn control in high-stress situations. Rather than stopping someone who's still learning the ropes from deadlifting, we can use a lighter weight to help them learn the movement and build up their anti-rounding strength.

As for managing these forward forces during lifting, planning a smart workout routine could be more helpful in avoiding injuries. The resistance to these forces mostly comes from our spinal bones. The stronger these bones, the more force they can handle. As bone strength can be increased with resistance training and plenty of rest, gradually increasing the weight over time could be a great strategy to build up tolerance and minimize the risk of injury.