I re-read my blog post on some thoughts I had about pain after listening to an interview with Stu McGill. It’s interesting to see how my thoughts on pain have developed since I wrote that post 1.5 years ago. I would like to challenge my former self about the ideas I wrote down and the statements I had agreed with back then:
“If you can do provocative testing and cause their pain to get worse by putting them in an awkward posture or stressing the pain somehow. If they say, “Oh yeah. That hurts more.” You’ve just proven that it’s a mechanical variable that makes their pain worse and probably if you can take that mechanical insult away, the pain will be less and hopefully even disappear.” – McGill
Does this prove that a mechanical variable (how would you even define that?) makes their pain worse? Or have you just proven that the posture you put them in or movement you made them do makes theit pain worse? Provocative testing doesn’t tell us why someone’s pain is provoked… it just tells us what movements/postures in this context provoke it. We can only hypothesize why it may be provoked – the reason is not proven by the results of the test.
It could very well be that the increased stress on those tissues is increasing nociceptive signalling, which could increase the likelihood of experiencing pain. The question still is: why is this person’s subconscious interpreting it as a dangerous situation when they probably would have been able to get into that posture without pain before? Are they getting a greater increase in nociceptive signalling than before? If so, why? Are there peripheral or central changes that amplify the nociceptive signalling?
Interestingly, Body in Mind recently wrote about a study that found that the onset of pain with head rotation among participants with persistent neck pain can be modulated by visual suggestions of more/less movement. So much for the idea that if pain is brought on and alleviated by very specific mechanical stress, it must be mainly a mechanical problem.
I’m not saying not to use provocative tests. I think that they can be a very powerful way to help patients buy into what you’re telling them (i.e. you elicit pain with a certain movement, do some sort of treatment, and then re-test to show them that their pain can be changed). Just be wary of jumping to conclusions about what your test is telling you, as well as what your treatment actually did (See the [quickly responsive] nervous system. Sorry Dre, I don’t like the terms “easily fooled”…).
“So maybe, if there was a study looking at the effects of improving biomechanics on pain (I know, very general question here), and it had the results described above [forty percent of the people had a positive effect of the intervention. 40% had a negative effect. The remaining 20% it made no damn bit difference.], overall it would seem like changing someone’s biomechanics has no statistically significant effects on their pain. But, perhaps it did help 40% of those subjects because for those subjects, poor biomechanics was the biggest risk factor for them. Whereas for the others, they had other larger risk factors that were not addressed so improving their biomechanics did not help their pain” – Myself
Uhh could I have been more vague? I will try to come up with a more specific example. I think this would be an interesting study to figure out why certain interventions work:
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Objectives of Study
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What This Would Tell Me
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Existing Research*
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Is exercise better than no exercise?
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Whether or not I should incorporate exercise into treatment for the purposes of reducing disability and pain
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A meta-analysis by Macedo et al (2008) found that motor control exercises were better than minimal intervention for improving pain and disability among participants with persistent, non-specific LBP.
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Does one intervention group experience greater improvements in disability and pain than others?
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Is there one type of exercise I should be focusing on? If they all provide equal benefit (and greater than no exercise), maybe the underlying reason for why they are all beneficial is the same. If that’s the case, it doesn’t really matter what I do as long as I give them some type of exercise
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It seems like there is some conflicting research for this. Two meta-analyses by Macedo et al (2008) and Smith et al (2014) found that motor control/stabilization exercises were no more effective than other types of exercise. However, a meta-analysis by Bystrom et al (2013) found that motor control exercises were more effective than other types of exercise.**
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What variables help to explain changes in disability and pain?
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How do exercises improve pain and disability? What should I really be trying to improve when I give patients exercises?
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I didn’t find any studies that included all the outcome measures in my imaginary study. Ferreira et al (2013) found that the strength of the therapeutic alliance helps to predict how well participants with persistent LBP respond to treatment. A systematic review by Wong et al (2013 – no relation) found that changes in TA activation were not associated with changes in pain or disability in people with non-specific LBP. In other words, TA activation did not need to improve in order for people to experience improvements in pain and disability (as well, improvements in TA activation don’t necessitate improvements in pain and disability).
Lastly, Costa et al (2011) found that self-efficacy helped to mediate the relationship between pain and disability in people with chronic LBP, whereas fear of movement did not. This was a prospective observational study that used an inception cohort so no intervention was done. Still, if self-efficacy is an important factor with mediating the relationship between pain and disability, could it be an important factor to try and change with our interventions?
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**I don’t think I understand well enough how meta-analyses are done yet to critique them so I don’t really know which one of these has the most trustworthy conclusions. I am open to learning though!
Too bad my former self has no way of responding to this. I still think biomechanics has a certain place, but not in the way that I thought it did back then. Biomechanics is such a general term. No wonder everyone is arguing about its importance. We probably aren’t even talking about the same thing when we argue for biomechanics having its place. One person could be thinking about the importance of training the core to “stabilize” a person’s spine to reduce their back pain. Another person could be thinking about the importance of considering how tissues respond and adapt to stress when tailoring your treatment.
I think I have gone from the former person to the latter. Thanks to Andreo Spina and Greg Lehman (and probably other people on the interwebs) for opening my eyes to this! I took Greg’s course on Reconciling Biomechanics with Pain Science in March and it was awesome (see course reviews by Jesse Awenus and Todd Hargrove). You could probably figure out everything in the course based on what he posts online for free (greatly appreciated!), but I highly recommend it if you want it packed up neatly in an engaging, interactive course. The CPA Pain Science Division is hosting his course at a special rate in Hamilton on Oct 3 and 4, 2015. Register now before it gets filled up!
2 comments to this article
Michelle
on August 13, 2015 at 1:43 am -
Very well-written post! I appreciate how reflective and thoughtful you are, and commend you for taking the time to challenge your past thinking.
“Still, if self-efficacy is an important factor with mediating the relationship between pain and disability, could it be an important factor to try and change with our interventions?”
Yes! I believe it is an important factor! I remember learning about self-efficacy back in school. When faced with difficult tasks, people with low self-efficacy give up quickly, have lower aspirations, and focus more on failure. On the other hand, people with high self-efficacy welcome these tasks as challenges that can be overcome. They are motivated and do not give up.
I think if patients have higher self-efficacy, then they would be more willing to exercise, move around, and experience improvements in their pain and disabilities.
VeeWong
on August 13, 2015 at 3:16 pm -
Thanks for your comments! The challenge now is to find strategies that are effective at increasing self-efficacy (and seeing if improving self-efficacy relates to improvements in disability!)