Chiropractic manipulation to gain strength and making a case for strength care for patients
PART I OF THIS ARTICLE introduced an intriguing approach to chiropractic care. The idea of “strength care” to gain strength arose from the increased strength observed in the hip flexor following manipulation of the navicular. Moreover, I explained how the strength gains were extinguished when unsupported feet hit the floor. On the other hand, strength gains were well maintained when the feet were supported with use of a custom-made flexible orthotic.
This is the second of two articles where I discuss some of the theories regarding the relationship between manipulation and strength. Additionally, I will discuss the clinical benefits and implications of manipulation to different parts of the spine in the context of strength gains in the upper and lower extremities.
Why it works
When I demonstrate this protocol to students, athletes or patients, I am often asked to explain why extremity strength increases with manipulation procedures.
Often, when asked this by a student, I will flip the question back to them in an effort to solicit their thoughts, ideas and theories regarding this interesting, yet sparsely understood phenomenon. A thorough search through peer-reviewed literature yields very little to explain the relationship between manipulation and strength in healthy individuals.
Is it due to traction?
Upon observing this procedure, my students will often say that increased strength must be attributed to the long axis distraction involved with manipulating the navicular bone. After all, the manipulation is applied by taking contact on the superior portion of the navicular, and applying a high-velocity, low-amplitude thrust in an inferior direction.
In doing so, there is concurrent traction to the hip joint and associated muscles. Some have argued that the increased strength may be attributed to the traction, resulting in a brisk stretch of the muscles around the hip, thereby activating them to become stronger.
While this “stretch and activation theory” is a plausible explanation, I have been able to refute this theory by achieving the same strength gains with manipulation of the navicular without any traction. This way of manipulating the navicular to gain strength was demonstrated to me by my esteemed colleague Mark Charette, DC. As he taught me this procedure, I recall him saying, “Look at the bottom of the foot. Find the top of the medial arch and thrust there!” In doing so, an inferior to superior thrust is directed to the navicular. Although this procedure does not induce any traction of the leg, it will still increase hip flexor strength, nonetheless. Traction theory debunked.
Is it due to proprioceptive changes?
Once the notion of the “stretch and activation theory” was no longer a consideration, some students would then suggest the strength gain was attributed to a change in the position of the navicular. Perhaps a change in position resulted in novel proprioception that “unleashed” strength elsewhere along the kinetic chain, in this case the hip flexor.
This theory is plausible as there has been a long-established relationship between novel proprioception and strength gains. When we couple this theory with the long-established understanding that orthotics can improve proprioception, it is no surprise to see why strength gains are maintained when the foot is supported with a custom-made flexible orthotic that supports all three arches of the foot.
There is more to the story
There are many other examples of manipulation-induced strength gain that can be maintained with supportive custom-made flexible orthotics.
For example, with rotary cervical manipulation, there are strength gains in the upper extremity. With torsional lumbar manipulation, hip abduction strength gains are noticed. Both outcomes have been observed to be maintained with the use of a supportive orthotic and extinguished when an unsupported foot hits the floor.
The common thread to these various examples of maintaining manipulation-induced strength gain seems to be the way the foot is supported. As we pursue a theory to explain this, naturally we may be compelled to attribute some of these benefits to the reflexive pathways within the foot that affect the rest of the body. Could it be that custom-made flexible orthotics not only support the foot, but also enhance reflexive pathways that contribute to maintaining manipulation-induced strength gains in a widespread manner throughout our body?
While it may take time to elucidate this fascinating phenomenon, what should not be underestimated in the interim is the value of integrating this approach to gain strength within your clinical practice by changing the way we conduct baseline testing. In future studies, it would be interesting to objectively measure how manipulation-induced strength gains could improve and enhance training and performance. For now, this provides a compelling case for strength care and complementing this care by supporting the feet with custom-made flexible orthotics.
DENNIS K. LIU, DC, is a graduate of the University of Toronto, Scarborough (BSc.), and Faculty of Medicine (M.Sc.). He graduated from the Canadian Memorial Chiropractic College (CMCC) in 2004, and currently practices in the provinces of Ontario and British Columbia. He has been teaching neuroscience at CMCC for the past 18 years. On campus he is also the Foot Levelers College Liaison, teaching students about the benefits of using a custom orthotic that supports the three arches of the foot. For more info, go to FootLevelers.com.
