While some researchers don’t mind giving human subjects contagious diseases or unproven chemical cocktails, they generally draw a line at purposefully inflicting physical injuries. So when a coincidental injury occurs in a well-monitored lab study, it’s definitely something to write home about.
I can think of maybe three I’ve come across over the years. In strength training circles, the 1992 paper titled “Lumbar Posterior Ligament Involvement During Extremely Heavy Lifts Estimated from Fluoroscopic Measurements” (1) by Jacek Cholewicki and Stuart McGill (of spine research fame) is a classic. The reason is pretty simple—Cholewicki and McGill caught real-time x-ray footage of a powerlifter’s spine buckling under load. The video demonstrated for the first time that a single joint could fail and lead to pain.
To quote the study, the authors were interested in assessing the “ligament and disc contribution in resisting trunk flexion moment during extremely heavy lifts performed by national class powerlifters.” The lift in this case was the conventional deadlift. Four lifters were asked to give baseline measurements of back function by having EMG tests done in a fully flexed position. This allowed Cholewecki and McGill to establish just when muscles ceased protecting the spine and left it all up to the ligaments.
After a warm-up period of their choosing, the lifters pulled beltless near max deadlifts in front of a video fluoroscopy machine (which, if you’ve ever seen live action x-rays of people eating, you understand how they work). The machine was positioned directly beside the lumbar spine for a clean saggital shot of the discs in action. The moment of interest occurred when subject two setup for his first of two planned deadlifts. His initial setup moved his lumbar spine out of the x-ray’s capture range. The attending radiologist asked subject two to change his position to get the lumbar spine back into the shot. The lifter shifted to accommodate the request and, in doing so, screwed up his start.
Because of the request, the lifter accidentally rounded his lower back instead of safely locking in his lower back and rounding only at the upper back. Subject two noted that he felt pain in his lower back but not enough to end his participation. If you’ve ever had a coach ask if you were "hurt" or "injured," this guy was just “hurt.” In fact, his second pull was technically far better than the first.
Cholewicki and McGill went back, digitally cleaned the footage, and began examining what had been recorded. If you’re curious about why the footage needed cleaning, the recording medium was VHS and the resolution was about the same as what you got from a Super Nintendo running in interlaced mode.
During the review, they saw a likely reason for why subject two noted some pain. While the rest of his joints stayed in a safe position, the L4-L5 joint* buckled (bent) forward during the first stage of the pull, stretching the related ligaments past the baseline measurement. Of the eleven ligaments and ligament bundles monitored in this study, all the ones attached to L4-L5 were stretched past baseline, and the anterior portion of the associated disc was slightly pinched during the joint rotation. None of the other lifters reached baseline.
The authors felt that the lifter simply activated his muscles in the wrong order or that he temporarily lost the exacting control of his muscles needed to protect the spine. Unfortunately, having a mass of metal EMG probes and wires would’ve blocked any attempt at an x-ray, so there isn't any record of muscle activation.
It seems pretty certain that no one before had captured such an act so clearly. In fact, over time this one unique point became the paper’s dominant feature. While the spine buckling was recognized as a topic of high interest, Cholewicki and McGill spent most of the twelve pages documenting and discussing the more generalized aspects of the entire group of lifters. These days, you almost never hear the paper discussed outside the context of subject two and the mechanics of his injury. Despite the time that has passed, the novelty of subject two’s back pain is still the most important aspect of the study. As it has passed from research into the public eye (largely thanks to McGill’s openness in discussing his work), it’s changed slightly from “Wow, I can’t believe that happened” to “Wow, that hasn’t happened again in a while.” To my knowledge, none of today’s spine/lifting studies have reproduced this incident or anything similar. If there have been duplications, they’re miniscule in number.
Why? Looking back at what happened, the simplest answer seems to be this—no other study actively distracted lifters during the setup. Think about how long you take to prepare for a heavy deadlift and how focused it is. From breath rehearsal all the way to getting the slack out of the bar, I can burn a few minutes and actually get a little tired during my setup. If someone came up to me during a trial and told me that my body position was invalidating my entire effort, I can see where my focus could go from lifting to making sure that my spine stayed in the x-ray plane. That’s nothing but trouble for a movement like the deadlift where your strongest lower back position puts you right on the edge of ligament strain.
This distraction element hasn’t got much attention because it takes a little digging to learn that it happened. In the original article, the distraction is only mentioned at the end and it’s too old for many libraries to circulate. On the internet, it’s behind a paywall. I had to get special permission through my institute to download it, even though we have a member account with a partner journal service. Finally, McGill’s own work, such as Ultimate Back Fitness, focuses on the incident (and rightfully so, given its importance) but not the situation that led to it.
Where ten years ago I might’ve seen this and reconsidered my interest in deadlifts, today subject two’s injury is almost reassuring. As Cholewicki and McGill state in the original study, none of the other lifters crossed over the baseline threshold and this was without belts and in a less than ideal environment. Getting into the anatomical details, disc shearing, compression, and the use of ligaments as actors in the lifts were negligible/nonexistent in all the proper lifts. In fact, the authors inferred that the motion of a heavy deadlift would protect the spine from shearing while repetitive lifting strengthens the spine itself and helps ward off compressive injuries.
In the end, I think it’s pretty unassailable that (in terms of spine health) you can safely pull big weights provided you keep your lumbar region tight and at or close to neutral and you don’t have any prior injuries, ailments, or distractions (particularly meddling radiologists) that could give out or take your focus away during the lift. I have to believe that this study formed some of the basis for McGill’s similar take on lifting injuries, as expressed during a recent interview with Bret Contreras: “People get hurt when they break form. They don’t get hurt when they pick 800 pounds off the ground if they do it well. When you talk to them, it was the one that they were not paying attention on” (2).
*McGill’s books refer to the buckled joint as L2/L3.
References
- Cholewicki J, McGill SM (1992) “Lumbar Posterior Ligament Involvement During Extremely Heavy Lifts Estimated from Fluoroscopic Measurements” Journal of Biomechanics 25(1):17–28.
- Transcribed Interview with Stu McGill. Retrieved online from: http://bretcontreras.com/transcribed-interview-with-stu-mcgill/