So you think you know how to measure and assess posture?
*notes: I don’t like the title ha, it sounds a bitty conceited but it did make you click and I figured it would be more interesting then “a thorough examination of the reliability of the visual assessment of the lumbar spine”. Anyways I think there is a valuable message here in examining the reliability of any practice you do as a trainer. Enjoy!
Posture; I haven’t talked about this subject in quite some time, frankly I’ve been spending more time focusing on learning more about strength training and programming. However, just because I haven’t really talked about it doesn’t mean I still haven’t been reading the research on it. In fact, Dr. Jonathan Fass and I are hopefully in the end phases of a research review on whether or not personal trainers should assess lumbar posture so it’s safe to say I’ve read a large percent of the relevant research on the subject.
Here’s the thing, I’m still noticing a lot of trainers talking about posture, specifically the alignment of the lumbar spine and its relationship to the pelvis (anterior pelvic tilt or posterior pelvic tilt). For simplicities sake let’s ignore the claims which include the alleged association between postural deviation and muscle imbalances and its association with pain and just focus on one question; as a personal trainer, do you really know how to assess lumbar posture? This means its accurate measurement and its change over time.
Let’s phrase this another way; your client wants to get stronger. You have a pretty good idea on how to measure a client’s strength. You might use the bench press or pull up for upper body strength or a leg press or squat for lower body strength. Now these are by no means gold standards for measuring strength but if a client can move more weight over time they have likely gotten stronger. So you have your assessment (leg press, squat, bench press, or whatever you decide to use) and you have your intervention which would be your training program. If your client gets stronger and they weren’t doing any training other than what you prescribed then your training program probably was the variable that changed their strength levels.
So you have your measure of strength which can be quantified by an actual number and your intervention which you predict will change the originally measured number. Now imagine how illogical it would be to say that you have a program that increases strength when you have no idea how to measure strength.
So before continuing to read ask yourself two questions (1) do you assess lumbar posture? And (2) do you know how lumbar posture is measured?
What is lumbar lordosis?
Lumbar lordosis refers to the anterior or inward curvature of the spine (Been).
How is lordosis measured and what is considered normal?
The problem with comparing data is that there are so many different ways people have measured lumbar lordosis. If you’re really interested check out this review by Vrtovec and colleagues. From what I’ve read, the Cobb method seems to be the standard. Cobbs method forms an angle by drawing a line at the superior endplate of L1 as well as a line at the superior endplate of the sacrum.
So what’s normal?
This table comes from Roussouly, Gollogly, Berthonnaud, and Dimnet. They found that the average value for lordosis was 61.4 degrees with a range of 41.2 degrees to 81.9 degrees with the number of vertebrae contributing to the lordosis being between one and eight. They also identified four different classifications of lordosis.
|Type 1||Type 2||Type 3||Type 4|
|Sacral slope||Less than 35 degrees||Less than 35 degrees||Between 35 and 45 degrees||Greater than 45 degrees|
|Lordosis range||41-64 degrees||44-58 degrees||43-76 degrees||61-82 degrees|
|Number of lordotic vertebrae||1.5-6||4-7.5||3-6.5||3.5-6|
|Prevalence||34 subjects||18 subjects||60 subjects||48 subjects|
Type 3 is considered a well aligned spine but none of the individuals in this study, despite the wide range had back pain complaints.
Furthermore, Lin and colleagues also measured lumbar lordosis in a sample size of 149 subjects. The researchers discovered that the mean lordotic angle of this sample was 33.2 degrees. With one standard deviation, normal lordotic curve was 20-45 degrees. Lastly, Murrie and colleagues generated a modified Cobb angle by measuring the angle created from a line drawn between the L1/2 and L5/S1 disc spaces. The measured lordosis covered a wide range of 20 to 80 degrees.
I don’t remember the exact study but in the review section a researcher was quoted (okay I’m totally paraphrasing) as saying there is no point in defining normal spinal curvature due to large variations within the population.
Can it be accurately measured?
The answer is yes, lumbar lordosis can be accurately measured. Unfortunately just not by those still conducting visual assessments (which to my knowledge is the only way I’ve seen trainers do it). According to Vrtovec, Perus, and Likar examination of spinal curvature becomes more accurate when the evaluation is completely automated meaning relative to computerized evaluation, visual inspection is considered to be subjective, unreliable, and inconsistent (Vrtovec).
In fact there are several variables that might confound your visual analysis including gluteal prominence and stomach size. In a presentation I did this summer on the subject I had three pictures, two of them were of me and one was of another person. In one of the pictures of me I padded my butt with a towel to make it look bigger. I asked the people in the audience to rate who had a larger lordosis. The padded picture of me was rated as having a greater lumbar lordosis than the non padded picture. For example in this study by Mosner and colleagues titled,a comparision of actual and apparent lumbar lordosis in black and white adult females, they found that gluteal prominence played a role in how investigators perceived the size of a persons lumbar lordosis.
The reliability of visual inspection doesn’t get better from there but I urge you to figure this out for yourself by reading this (if you need the pdfs I can get them for you just message me or email me Justin.firstname.lastname@example.org).
Here’s the bottom line, there are a wide variety of spinal curves that are all nonpathological and thus considered ‘normal’ although the fact that there are so many acceptable values makes the term normal basically useless. Next, research does not support the use of the visual assessment for posture. I’m going to list over 40 references below on lumbar lordosis, its measurement, association with pain, and muscle imbalances. If you’re a personal trainer and still evaluate spinal curvature I strongly urge (no insist) that you at least read some of these references from each category to evaluate your practice. I will be happy to supply pdfs if any readers want them.
Finally, don’t take this the wrong way. I am not saying lumbar posture is totally irrelevant. Some postures may be aesthetically unappealing to the person with said posture and some postures have been associated with pain (read Adams reference) although the evidence is not in favor of that claim. All I am saying here is that if you want to continue assessing lumbar posture please find a way to do it reliably.
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Been E and Kalichman L. Lumbar lordosis. Spine J 14: 87-97, 2014.
Britnell Sj, Cole JV, Isherwood L, Sran MM, Burgi S, Cardido G, and Watson L. Postural health in women: The role of physiotherapy. J Obstet Gynaecol Can 27: 493-510, 2005
Bryan JM, Mosner E, Shippee R, and Stull MA. Investigation of the validity of postural evaluation skills in assessing lumbar lordosis using photographs of clothed subjects. J Orthop Sports Phys Ther 12: 24-29, 1990.
Chaleat-Valayer E, Mac-Thiong JM, Paquet J, Berthonnaud E, Siani F, and Roussouly P. Sagittal spino-pelvic alignment in chronic low back pain. Eur Spine J 20: 634-640, 2011.
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