Last week we spoke about some ways to make deep squats safer for the knees. This week we talk spinal health. So, does long term exposure to heavy loads in the squat increase the likelihood of low back pain? Like in the knee, this is a tough question to answer (Although if Justin Timberlake is spotting you during stability ball squats it may help). It will also probably depend on the individual. As in the knee, we can glean a bit of information from weightlifting research. As described before, these athletes tend to do quite a bit of squatting. Just keep in mind that these individuals usually have some sort of coaching, programming and tend to have a knack for lifting. Like in most other cases, this research can’t be fully expanded to a general population. Either way it gives us some great information:
- Former weightlifters aged 40-61 years old report (survey data) report less low back pain then an age matched general population (2)
- Weightlifters show similar rates of spinal abnormalities as other elite sports (2)
- Chronic weightlifting improves vertebral bone density and ligamentous stiffness (2)
At least from this research, squatting does seem like it may be relatively safe (and potentially protective) in weightlifters. This is of course in individuals who are well practiced in squatting. However, low back pain is reported in sports that utilize and test the squat (And in powerlifters it is one of the most common complaints of pain) (3). It makes sense that we should take precaution when undertaking any program that loads the spine.
What Factors Effect Stress on the Spine and How can we Decrease the Likelihood of Injury ?
1 – Spinal Position
Common dogma with the squat is to keep the lower back (lumbar spine) flat, also known as a neutral position of the spine. Most people understand this, but don’t understand why this is important or what happens when we flex (bend forward or round) the spine and load it.
If you’ve read anything from Dr. Stuart McGill you’ll know why keeping the spine in a neutral position is important. So what happens when we load the spine into flexion?
- Low back extensor musculature loses it’s ability to produce force and thus the spine is exposed to more shearing (check 2 articles ago in the series for a primer on shear forces) (1)
- More stress is placed on the passive posterior structures of the spine, stressing these structures (also increasing shear forces) (1)
- Classic disc herniation appears to be associated with repeated flexion motion with only moderate compressive loading required (1) (Keep in mind that most people aren’t loading into end range flexion every rep of a squat)
Obviously it makes sense that individuals should be coached on optimal technique and should not allow spinal flexion to occur with loaded squatting
2 – Mobility
Lacking hip or ankle dorsiflexion range of motion will result in an athlete flexing their lumbar spine in order to reach depth in the squat. This is also effected by stance and boney structure as described earlier in the article series. Find my fixes for hip and ankle mobility in my previous articles.
3 – Load
Compressive loads on the spine directly correlate with weight used (2).
More Weight = More Stress
Interestingly, deep squats might decrease stress on the lumbar spine due to an athlete not being able to utilize as much weight in a deep squat as in a partial range squat. Just keep in mind that a deeper squat requires more mobility to complete with a neutral spine. Butt wink is a common term to describe spinal flexion at the bottom of a deep squat and should be minimized to keep spinal stress minimized.
As a coach I’m sure you’ve seen an athlete lose their lumbar spine position with heavy loading. If a load exceeds an athlete’s ability to keep a neutral spine an athlete may flex the spine to get a mechanical advantage by stretching passive ligamentous structures of the spine. This may get the weight up, but also puts excess stress on the spine in the process.
Like most physical stresses on the body, weight should probably be slowly increased with special attention toward optimal technique.
4 – Torso Inclination
More forward inclination of the spine during a squat increases anterior shear forces on the spine and increased tensile forces on intervertebral ligaments (2). Interestingly, pushing the knees back during a squat will decrease forces on the knee during the squat but places more stress on the lower back (This is due to the change on torso inclination).
Powerlifters tend to adopt a low bar position and push the hips back more during a squat. This increases torso inclination and is used to increase the load lifted. Olympic lifters tend to stay more upright in their lifts, which carries over to the olympic lifts well. This may explain the increased incidence of low back injuries in powerlifters and increased incidence of knee injuries in olympic lifters (3)
Pick your poison. Each individual will most likely have an ideal squat technique based on their goals and individual differences in boney structure, injury history and mobility. Just keep in mind that your torso inclination directly affects knee and low back stress (Think of the implications for low back patients and return to squatting following injury)
5 – Exercise Selection
Based on weights utilized and torso inclination, we can easily determine the most challenging exercises on the spine, and the least challenging. Here is a list of squatting movements from most to least stressful on the spine:
- Partial range – low bar powerlifting style squat (hip dominant)
- Full range low bar powerlifting style squat (hip dominant)
- Full range high bar olympic lifting style squat (quad dominant)
- Full range front squat
- Full range overhead squat
- Full range goblet squat
Again, when trying to moderate total spine stress in a training program, these things should play a role.
6 – Fatigue
Fatigue pitches people forward in the squat (2) thereby increasing compressive load and shear force in the spine. Ensure stopping your set when you reach technical failure and rest adequately between sets. Don’t sacrifice form for more reps.
7 – Spinal bracing
Most successful athletes tend to spinal brace really well without even realizing it during their lifts. Spinal bracing is the activation of trunk musculature prior to loading the spine. Teaching athletes how to adequately activate their trunk musculature prior to lifts will create increased intra-abdominal pressure resulting in a stiffer structure to decrease spinal buckling in the squat (1).
This may be simple and most people probably do this intuitively, but some don’t. If we aren’t stiffening the spine then we aren’t as able to buffer shear forces during the squat, potentially increasing risk of injury and decreasing potential load lifted in the squat.
So there you have it. Way too much information on the squat spread over 8 parts. Hopefully you come away with a greater understanding of the stresses on the spine during the squat, and ways of making this lift a bit safer for yourself and athletes you coach.
Please share this article if you know someone who could benefit from it and as always thanks for reading!
Does sitting in a chair count as training your squat?
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Works Cited:
- McGill, S. (2007). Low Back Disorders. Champaigne, IL: Human Kinetics.
- Hartmann, H., Wirth, K., & Klusemann, M. (2013). Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load. Sports Med.
- Keogh, J. (2005, May 1). The Powerlifter’s Injuries. Pure Power Mag, 4-12.