Load. Re-Load. Common principals of the physio practice. Perhaps unbeknownst to the average metal fan, Metallica’s themes are often heavily laced with physical therapy metaphor, even to the extent of album names. This blog takes a look at some basic principals of loading, as well as some tangible thoughts as to clinical implication.
First, lets look at general mechanical loading of a common treatment area in clinic: Lower Back Pain. Mechanical loading is healthy, and beneficial for a spine. Loading prompts tissue repair, regeneration, and tissue adaptation, which is why proper loading is crucial to returning injured tissue (think post total hip, patients are walking day 1) or uninjured painful tissue (insert your patient’s complaint here, post-average tissue healing time.) However, localized loading at abnormally high doses, or doses exceeding the given tissues relative tolerance, can result in a pain response in that innervated tissue. The vertebra itself, as well as disc (mostly peripheral annulus), facets and ligaments are all rich in nociceptive free nerve endings. Thus all these structures have capacity to experience pain.
A patient’s loading strategy can be altered, when the patient is in pain. Things affecting the loads on the spine can be abnormal muscle tension, guarded or aberrant motions (adaptive or mal-adaptive), the patient’s perception of the task (“I know this movement will cause pain!”), and of course the excessive “un-silenced” nociceptive inputs that the painful area has acquired. Some potentially useful things research has shown us regarding patients with back pain:
- EMG studies have demonstrated that when normal people bend forward, their back muscles are temporarily inhibited and silent, though when patients with back pain bend forward the back extensor muscle EMG shows the muscles remain active. (Ahern et al 1988, Adams et al 2002)
- LBP patients have reduced positional sense (or “JPE/ joint positional error as much of Dr. J. Trevelean’s research on the cervical spine after whiplash has demonstrated) possibly due to altered proprioceptive nerve function (Brumagne et al 2000).
However, we need to remember that when considering our patients ability to perform certain exercise or contract certain muscles (Hodges and Richardson show delayed TrA contraction in LBP patients), even if we CAN assess these minute altercations, we are assessing under the influence of pain. These aberrant findings may start as a protective response to pain (to a real, biomechanical trigger), and last as a cycle induced by sensitized tissue, without actual damage or physiological need for protection.
Once tissue is sensitized, pain thresholds are lowered (your bodies way of “monitoring” the site of initial increased input/information), and often you end up with the full package (lets call this the Pain Response Package, or PRP): quality of movement changes, muscle tension relationships change, suddenly activities that were prior oblivious to one’s stream of consciousness are suddenly approached with a flood of pessimistic and often fearful cognitive processes- which has potential to further affect behavior and experience of the given task. Suddenly Granny views a patio step as the trail of tears. The pain response package (PRP), for understandable reason, often yields a deconditioned state of the painful area, and with some, a deconditioned body.
Enter Metallica, enter the sandman, enter loading. What do we know about avoiding loads to the body (ie immobilization)? It is a catalyst to deterioration, and joints undergo physiological changes that amount to softening of cartilage, chemical changes, and structural changes for the worse (http://www.ncbi.nlm.nih.gov/pubmed/3581580). Now, most people in pain have not become completely immobilized, but at a tissue level the collective processes that lead to poor tissue health begin. If you put your elbow in a brace for 6 weeks, is it stiff upon removal? Does your back pain patient also have stiffness? Is there tissue starting to undergo a change, for the worse?
The patients reaction to the PRP (all the things that come along with pain) IS a DYSFUNCTION- it doesn’t necessarily entail permanent damage, irreversible damage, or any real damage at all on a tissue level. I will take a moment to note that unloading has its place (think heel lift for severe Achilles tendonitis), and Metallica could have introduced a short EP titled “Unload”, which can be a necessity for your patients at times- but these times should be brief, with the anticipation of load and re-load on the horizon.
So this can simplify some things: we as physios are always looking for “the cause” and verbally manifesting (sometimes off-the-cuff) elaborate explanations of the culprit, and what needs to be “fixed”. Our credentials can be elongated and our identities given an ego boost, in becoming “certified” in a litany of methods of assessment and treatment, which usually become the reference grounds for our explanations to patients, hopefully watered-down. But we don’t have to have an external cause for pain, and scare the patient with images of their degenerating disc. It is the present state of the patient that should be of concern (argues Waddell in “The Back Pain Revolution”, 2004). So is the dysfunction a loss of physical capacity, or a matter of performance? Waddell asks. Treatment can be effective, but research is showing its efficacy is likely “non-specific” (sound like familiar terminology from the past few decades of research in manual therapy?) The manifestation of physical dysfunction (all the things we eagerly jot down about hypertonicity, stiffness, shortness, strength and quality) are much more important than the long-deceased trigger, and can all potentially affect loading. And they are all part of the current state the patient presents themselves in. And keep in mind, the “trigger” is what the patient is sweating, as they have been ruminating thoughts of certain aforementioned “collapsing discs” and “arthritic facets” and other forebodinglingo ejected from the mouths of their trusted lab-coat donning MDs, as well as perhaps other physios and WebMD.
The BIOMECHANICS of the patient’s current pain state MATTER, though it may be a paradox: they may not matter in the sense of the “trigger”, but they matter in the “response” to the trigger. 2 points to illustrate this concept:
- Take a patient that once suffered sciatica, and got better after 6 months: This person with discogenic radiculopathy, in raging pain at its onset, will have the SAME MRI result when they are happily sipping tea, free of all pain, 6 months later.
- Complaints of back pain do not increase with age, but peak in mid life- thus all the biomechanical things we consider about facet compression with position and loads and tissue tolerance do NOT necessarily abide by the rules of biomechanics in relation to pain (they don’t seem to have a linear, or positive relationship, when looking at the lifespan).
So when a patient is in a state where normal afferent input = interpreted as pain, loading plays a vital role in the road to recovery. Loading is a broad term, and can be applied through simply moving, isometrics, isotonics, etc. This is where physical therapist can apply relevant information gathered from their assessment to help their patient improve. We can educate the patient with a concept as simple as “Wolff’s Law”, the theory developed by the German anatomist and surgeon Julius Wolff that states that bone in a healthy person or animal will adapt to the loads under which it is placed. Use Wolff's law as a euphemism when explaining stenosis and bone spurs: its just your bodies way of trying to increase surface area to disperse load!
Questions to ponder:
- Is the painful area subject to higher loads that could be temporarily avoided by changing mechanics, to allow desensitization? (can you temporarily change the way they are performing a painful task, to load different tissue, strengthen out of the familiar painful ream as to return to it at a later time when tissue tolerance increases?
- Does their body allow options for movement strategy? If every time your patient squats they fall into the exact same pattern, do they have the strength or control to perform this task outside of that pattern?
- What load can your patient tolerate without a “flare-up”? Can the patient conceptualize this? What we know about tissue adaptation should support this as a starting point, and encourage progressive loading in low level pain zones. Build upon this and make sure the patient is noting their loading tolerance as they improve!
- Are there restrictions in the patient’s movement that may be causing the loading to be overly repetitive and unnecessary? Are these restrictions tissue-length based, joint-restriction based, or fear/avoidance based? What areas can we work on to change this?
- What lifestyle loads may be contributing to sustained protective behavior? Can we alter how they are working, sitting, standing, with education that this is only a temporary need to break the cycle of protection?
Loading can be simple, or complex, and research is still being conducted to help physios understand how particular tissues respond to particular loading.
For tendons alone, a see:
Michener et al. J Orthop Sports Phys Ther 2015;45(11):829-832. doi:10.2519/jospt.2015.0114
Plinsinga et al. J Orthop Sports Phys Ther 2015;45(11):864-875. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5895
Couppe et al. Journal of orthopaedic & sports physical therapy | volume 45 | number 11 | november 2015 | 853
The underlying theme however, is there is rarely a time when all forms of loading need to be avoided, and that loading does not have to be overly specific to result in decreased pain and increased function.
-Tal Blair, DPT
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