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Is rounding your back on deadlifts dangerous?
Introduction
If there's one thing I've posted about that triggers intense discussion, it's the question of spinal flexion and injury.
Unlike many lifting debates, just about everyone, regardless of whether they train, has been taught that lifting with a round back is essentially an injury waiting to happen.
Let's examine the actual science and logic of this.
What science supports it?
The most commonly cited research by proponents of the 'round back = bad' camp, is that of the now somewhat famous biomechanist, Stuart McGill.
What people don't know, is that this is in vitro animal research. In other words, they used spines of dead pigs. These spines were loaded through many flexion-extension cycles (up to 5,000 a day), until a disc injury occurred.
There are a few problems here.
These are many more loaded flexion-extension cycles than we would ever go through in even a week of training. The average lifter at most would do maybe 30-50 working reps on deadlifts in a week. It reminds me a bit of the frenzy over artificial sweeteners research, where mice were fed more aspartame in a day than a human would go through in a month.
To me, McGill's research is useful because it illustrates the mechanism by which disc injuries occur. However that doesn't indicate that the same movement at any load is dangerous. After all, appropriately dosed sprints are becoming known as the best way of preventing hamstring injuries in field sports, despite them also being the main cause for hamstring injuries. The dose decides if something is medicine or poison.
Lastly, dead spines can't adapt. Living spines are surrounded by supporting musculature. The muscles definitely adapt to load. There is a big debate about whether or not the spine can adapt, which brings us to our next point..
Can the spine adapt?
Many will argue that the spine is unique in that it is not as well vascularised as other tissues, and that this stops the annulus fibrosis from adapting to load. The idea is that rounding the back will put stress on the annulus fibrosis that it won't get any better at handling load, leading to an eventual disc bulge/herniation.
We know that exercise in living animals that involves flexion-extension cycles can have positive effects on the discs.
In humans, runners and rowers have been shown to have positive disc adaptations as well. Rowers in particular certainly undergo quite a bit of repetetive, loaded flexion in their training. This study found rowers initially had more lower back pain than cross country skiiers, but there was no difference after a 10 year follow-up.
Now, where research is concerned, I actually think it's so sparse here that it's pretty hard to have a strong opinion on the matter.
My take to the spine adaptation thing is: I don't know. What I do know is there seems to be plenty of people who lift in flexion with no pain, and people who don't even train with debilitating back pain. Therefore I learn toward assuming the spine follows Davis' Law. I just don't think humans would have gotten very far if such an important region of our body was tragically the only one that can't adapt.
But perhaps most critically, whether or not the spine can adapt to loaded flexion, might not even matter, because...
You're ALWAYS flexing when you lift
Many of you might be surprised to discover that research has shown that even in people who look like they are lifting with a flat/neutral spine, anywhere from 30-80% of max spinal flexion is actually occurring during squats and deadlifts. This calls into further question the pig spine research, given that it demonstrated herniations with as little as 30%. (Check out Greg Lehman's post for a deeper discussion of some of this research.)
In other words, what utility would spinal flexion be as a risk factor, if the amount needed to create injury is actually beyond what we can control anyway?
Now, you might say that it's just maximal or near end-range flexion that will cause issues. We just don't have research on that. Although myself, my clients, and many more have been performing exercises like jefferson curls for years, with no issues.
Injuries during flexion: a self-fulfilling prophecy?
I'm not lying when I say I've never actually seen a deadlift injury while lifting in flexion. In fact, I think in person I've maybe seen one or two acute injuries during any deadlift. Such is the tiny injury risk of lifting relative to other sports.
That said, i'm not gaslighting. I absolutely believe people get hurt lifting with all kinds of lifting postures. So why do so many claim to have seen it with the low back, if the research doesn't support it?
Well, as we've noted, load is the primary risk factor for injury. Most people who are trying to keep a flat back on deadlifts, are only going to get pulled into a rounded position when they are attempting something much heavier than usual. So we have a scenario where the person in question:
Is being exposed to a position they've never trained
Is doing so with a weight so heavy, that they can't control their technique
...Call me crazy, but I think it's fair to say that the most likely cause of the injury here was the weight they were using. In fact, it's my opinion that this person would have been less likely to get hurt if they were already including some loaded flexion in their training.
Conclusion
This is an article I plan on adding to, hopefully when some better research emerges.
As things currently stand, we know very little about the effect of loaded flexion on injury risk. Certainly too little to assume it is as bad as most online movement gurus make out..
There is some research indicating it could be positive for the discs, but ultimately we are left with principles like load management, Davis' Law and the abundance of anecdotal evidence that people can lift with at least some flexion without issues.
I think as long as you are training with smart loading and preparing for the goal task, you're doing about the best you can.
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