Manual Therapy (Part 2/3): What we -ARE- doing

In the *first post* of this series I argued that the traditional explanatory framework for manual therapy is outdated and should be tossed in the trashcan. However, clinicians and practitioners alike still see positive results with manual therapy interventions so clearly something is going on… but what is it? What are we as practitioners doing?

We are generating positive effects through primarily non-biomechanical means

The human body is complex and the traditional, biomechanical explanatory models for manual therapy were idealistically simplistic. Based on our current understanding, the observed effects of manual interventions appear to occur through a combination of various peripheral, mechanical, spinal and supraspinal mechanisms.¹ A detailed explanation of this can be seen in the chart below and the corresponding article by Bialosky.¹

Credit: Bialosky 2009¹

 

More simplistically – we produce change on the neurological and physiological level that appears to be moderated by patient’s beliefs and expectations.^1,2

On the neurological level — the interventions generate both a widespread hypoalgesic and neuromuscular response. Physiologically the interventions generate changes at the endocrine level as well as inflammatory change. Now, this can get into a chicken-or-egg argument of which comes first, but the end effect of these responses together is decreased pain and changes in muscle activity. Unsurprisingly the magnitude of change is moderated by the patient’s expectations and beliefs regarding the intervention (the brain is a powerful thing.)² This also makes sense since we know from an earlier post (*see here*) that pain is mostly about how the brain sees and interprets information. *Note that nowhere did I say we are making a physical change that resulted in the effect… because again we are not – although the physical input we produce with our hands is a component (see bottom left of the chart.)

Alright, that’s great and all but what does this mean for the clinical effects?

Mostly, it means manual therapy interventions have the capacity to do a lot of funky, cool things. This is since we are generating an effect on the nervous system and physiological level rather than the skeletal and fascial systems. Because of this manual interventions can:

 

Decrease pain locally and globally^3-6 – Fernandez-Carnero⁶ in 2008 found a decrease in pain in patients with lateral epicondylalgia following a cervical manipulation. Bialowsky³ in 2010 found changes in thermal pain sensitivity at sites both locally and distal to the spine following lumbar manipulation (in asymptotic patients.) Similar patterns were found by multiple other authors.^3-6

• So, we can apply manual interventions to improve pain not only at the painful location but even apply the intervention to an asymptomatic area to improve the painful location.

Change muscle activity patterns and strength^6-10 – Dunning in 2009⁷ found a change in resting EMG of the biceps immediately following a cervical manipulation. Lieber in 2001¹⁰ found improved lower trapezius strength after mobilization to the thoracic spine (in asymptomatic patients – so it wasn’t just due to a change in pain.) Additionally, Abbot in 2001¹⁰ found improved grip strength after elbow mobilizations with movement in patients with lateral epicondylalgia. Similar patterns were found by several other authors.^6-10

• So, it appears manual interventions can change not only resting sympathetic tone of muscles, but also force production. How this compares to just a general warm up or active motion I can’t say as I am unaware of any literature comparing the two on this measure.

Improve range of motion¹¹ – Abbot in 2001¹¹ found improved shoulder range of motion following elbow mobilization with movement in subjects with lateral epicondylalgia on both the affected and unaffected side (weird right?) An interesting point on the range of motion front is that it does not appear manipulations improve ankle range of motion in asymptomatic individuals.^12,13

• This helps support the argument that we are not inducing true, physical change with our interventions. It may also indicate that manual techniques are most valuable for improving range of motion when the individual is limited by pain or a protective muscular response (aka guarding) due to the hypoalgesic and neuromuscular response. However, I am unaware of studies examining range of motion of other joints in asymptomatic subjects, so it’s possible that the interventions can still improve range of motion otherwise (which would make sense if it alters sympathetic activity of the surrounding musculature — and we know range improved on the unaffected side in the Abbot study.)

 

This is neat and all, but what does it mean for the response I’m seeing from patients?

The big take-away is that we need to re-frame what we think is going on when a patient’s pain, range of motion, etc. improves. Did your patients pain improve after a mobilization or manipulation? That’s awesome! But attribute it to those neurophysiological changes paired with the patient’s beliefs and expectations. Did your patients joint mobility improve? Also awesome! But attribute it to changes in muscle sympathetic activity and potentially pain rather than releasing an adhesion or changing the joint interface. Did something feel like it has gone back in place or a muscle released, and the patients range and pain improved? Pretty great! But attribute it to pain decreasing (due to the hypoalgesic affect) and sympathetic tone changing (due to both the neuromuscular response and decreased pain) which results in less muscle guarding and limitation due to pain.

Oh… and FOR THE LOVE OF GOD do me a favor and don’t tell your patients you put them back in place as you may be helping encourage maladaptive beliefs, behaviors and further sensitizing them to pain. (Plus it’s an enormous pain to explain that things don’t go out of place and get them to buy in after the idea has been previously beaten into them by other practitioners.)

Quick Recap:

• The effects of manual therapy occur through an interaction of peripheral, mechanical, spinal and supraspinal mechanisms
• Manual therapy generates neurophysiological rather the biomechanical, tissue-level change
• Manual therapy techniques can improve pain both locally and globally,
• Manual therapy techniques can change sympathetic muscle activity and improve strength
• Manual therapy techniques can improve range of motion, but the utility is reduced in asymptomatic individuals
• Don’t tell your patients that you put them back in place (but really)

 

Okay…. All this theory is cool but how do I implement this information into practice?

I’ll be covering my perspective on how to integrate this information into practice (and why it’s important) in the last part of this series
(Update: *Click here for part 3 for my perspective on the clinical application*)

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Thanks for reading

~Adam

References:

1. Bialosky JE, Bishop MD, Price DD, Robinson ME, George SZ. The mechanisms of manual therapy in the treatment of musculoskeletal pain: a comprehensive model. Man Ther. 2009;14(5):531-8. (https://www.ncbi.nlm.nih.gov/pubmed/19027342)
2. Bishop MD, Mintken PE, Bialosky JE, Cleland JA. Patient expectations of benefit from interventions for neck pain and resulting influence on outcomes. J Orthop Sports Phys Ther. 2013;43(7):457-65. (https://www.ncbi.nlm.nih.gov/pubmed/23508341)
3. Bialosky JE, Bishop MD, Robinson ME, George SZ. The relationship of the audible pop to hypoalgesia associated with high-velocity, low-amplitude thrust manipulation: a secondary analysis of an experimental study in pain-free participants. J Manipulative Physiol Ther. 2010;33(2):117-24. (https://www.ncbi.nlm.nih.gov/pubmed/20170777)
4. Coronado RA, Gay CW, Bialosky JE, Carnaby GD, Bishop MD, George SZ. Changes in Pain Sensitivity following Spinal Manipulation: a Systematic Review and Meta-Analysis. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology. 2012;22(5):752-767. doi:10.1016/j.jelekin.2011.12.013. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3349049/)
5. Cliborne AV, Wainner RS, Rhon DI, et al. Clinical hip tests and a functional squat test in patients with knee osteoarthritis: reliability, prevalence of positive test findings, and short-term response to hip mobilization. J Orthop Sports Phys Ther. 2004;34(11):676-85. (https://www.ncbi.nlm.nih.gov/pubmed/15609488)
6. Fernández-carnero J, Fernández-de-las-peñas C, Cleland JA. Immediate hypoalgesic and motor effects after a single cervical spine manipulation in subjects with lateral epicondylalgia. J Manipulative Physiol Ther. 2008;31(9):675-81. (https://www.ncbi.nlm.nih.gov/pubmed/19028251)
7. Dunning J, Rushton A. The effects of cervical high-velocity low-amplitude thrust manipulation on resting electromyographic activity of the biceps brachii muscle. Man Ther. 2009;14(5):508-13. (https://www.ncbi.nlm.nih.gov/pubmed/19027344)
8. Makofsky H, Panicker S, Abbruzzese J, et al. Immediate Effect of Grade IV Inferior Hip Joint Mobilization on Hip Abductor Torque: A Pilot Study. J Man Manip Ther. 2007;15(2):103-10. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2565609)
9. Abbott JH, Patla CE, Jensen RH. The initial effects of an elbow mobilization with movement technique on grip strength in subjects with lateral epicondylalgia. Man Ther. 2001;6(3):163-9. (https://www.ncbi.nlm.nih.gov/pubmed/11527456)
10. Liebler E, Tufano-Coors L, et. al. The Effect of Thoracic Spine Mobilization on Lower Trapezius Strength Testing. J Man Manip Ther. 2001;9(4):207-212
11. Abbott JH. Mobilization with movement applied to the elbow affects shoulder range of movement in subjects with lateral epicondylalgia. Man Ther. 2001;6(3):170-7. (https://www.ncbi.nlm.nih.gov/pubmed/11527457)
12. Fryer GA, Mudge JM, Mclaughlin PA. The effect of talocrural joint manipulation on range of motion at the ankle. J Manipulative Physiol Ther. 2002;25(6):384-90. (https://www.ncbi.nlm.nih.gov/pubmed/12183696)
13. Beazell JR, Grindstaff TL, Sauer LD, Magrum EM, Ingersoll CD, Hertel J. Effects of a proximal or distal tibiofibular joint manipulation on ankle range of motion and functional outcomes in individuals with chronic ankle instability. J Orthop Sports Phys Ther. 2012;42(2):125-34. (https://www.ncbi.nlm.nih.gov/pubmed/22333567)