Spinal Manipulation: Pros, Cons, Mechanisms of Action

Discs never slip

Pros: There is evidence that suggests that spinal mobilizations a.k.a. manual therapy a.k.a. chiropractic adjustments a.k.a. high-grade joint play, can have interesting neurophysiological (mind-body) effects, albeit by not actually structurally altering the spine in any way.  Vertebrae don’t shift or slide or “sublux” spontaneously.   Jason Silvernail has aptly stated that, “Spinal mobilization engages several pain relief mechanisms in the body primarily through neuromodulatory and endocrine pathways – not through affecting structure of the joints or effecting connective tissue through direct structural change.”

Mechanisms of Action of Spinal Mobilization: http://www.ncbi.nlm.nih.gov/pubmed/26751060/

“Evidence suggests that spinal mobilizations cause neurophysiological effects resulting in hypoalgesia (local and/or distal to mobilization site), sympathoexcitation, and improved muscle function. Mobilizations have no effect on temperature pain threshold. Three of four studies reported reduction in spinal stiffness, heterogeneous in location and timing. There is limited evidence (one study in each case) to suggest that mobilizations produce increased nociceptive flexion reflex threshold, improved posture, decreased concentration of substance P in saliva, and improved sway index measured in cervical extension. Evidence does not support an effect on segmental vertebral movement.”

Cons: At about 13:15 – Harriet Hall describes how cervical (neck) manipulation is involved in causing tears in the delicate lining of the vertebral arteries, which can cause clots, which can lead to strokes.  One estimate posits that 20% of basilar strokes, or 1300 strokes in the U.S. per year, are caused by cervical spinal manipulation…and this could actually be an under-reporting of the numbers, because neurologists might not inquire about prior cervical manipulation upon meeting a patient.

Conclusion:  Manipulation might be useful in helping patients get out of pain, and return to function, however, cervical (neck) manipulation should probably be avoided.


Static Stretching: “Stretching” the Truth

PainScience: Full Article

Stretching research clearly shows that stretching is not an effective warmup

“Nothing about static stretching is more clear. Your basic quick (static) stretch warmup is one of the most studied topics in all of musculoskeletal health care and exercise science. For instance, a huge 2011 review of all the research found “overwhelming evidence that stretch durations of 30-45 seconds … imparted no significant effect” and even some evidence of harm.13

Um, harm? Yep: a 2014 test found that a nice pre-run stretch causes “a reduced capacity of the skeletal muscle to produce explosive force.” Yikes! As Alex Hutchinson put it for Runner’s World, “I can’t see anything good about something that makes me go slower but feel like I’m trying harder.”

“Acrobats, gymnasts, yogis, contortionists, and martial artists have clearly been pushing the limits for centuries, sometimes achieving uncanny mobility. But these are highly motivated athletes with specific and exotic performance goals and stretching regimens that woulddefinitely intimidate the rest of us, and with good reason: they often injure themselves along the way. Indeed, it may even be necessary to injure joints — to traumatize their capsules and ligaments — in order to get them to move that far.

Fitness and health are not equivalent. You can be fit for a particular athletic pursuit, but that doesn’t mean you are a healthier person: high performance in a narrow category often comes at great costs (such as joint stability). Flexibility is “good for” a few things … and really not much else. It’s useful for gymnasts, for instance …”

Dose-Response Relationship – Exercise and Mortality

The Dose-Response relationship with regards to mortality rates is an important concept.

The following review, link to review, was published in JAMA Internal Medicine and came to the following conclusions:

Conclusions and Relevance  Meeting the 2008 Physical Activity Guidelines for Americans minimum by either moderate- or vigorous-intensity activities was associated with nearly the maximum longevity benefit. We observed a benefit threshold at approximately 3 to 5 times the recommended leisure time physical activity minimum and no excess risk at 10 or more times the minimum. In regard to mortality, health care professionals should encourage inactive adults to perform leisure time physical activity and do not need to discourage adults who already participate in high-activity levels.


Hormesis or the Biphasic Dose Response

The biphasic dose response, aka hormesis, aka proper dosage, aka the “sweet spot”, is an incredibly important concept in all-things medicinal and/or health related.  It is the phenomenon whereby low-levels or small amounts of a stressor (ex. exercise, alcohol, curcumin/turmeric) can have beneficial or pro-adaptive properties.

Biphasic Dose Response

Neuroplasticity + Norman Doidge

Pretty remarkable stuff. Norman Doidge, featured in this video, who has been responsible for getting the concept of neuroplasticity into the maintream, was also responsible for kick-starting my interest in LLLT(low-level lasers)/photomedicine (I however use it strictly for musculoskeletal conditions).

He is featured here in a Nature of Things episode on the CBC.  The concept of neuroplasticity is changing the way that schizophrenia, PTSD and OCD are being treated.


Nutritional Epidemediology: A Mess

Nutritional epidemiology is a stickier than molasses because of the innumerable confounding variables present in studies on food consumption.  This article is excellent You Can’t Trust What You Read About Nutrition , and here are my favorite excerpts from it:

“A few years back, Jorge Chavarro, a nutritional epidemiologist at the Harvard School of Public Health, advised that women trying to conceiveconsider swapping low-fat dairy foods for high-fat dairy products such as ice cream, based on FFQ data from an ongoing study of nurses. He and his colleague Walter Willett also wrote a book promoting a “fertility diet” based on the results. When I reached Chavarro this week to ask how confident he was in the link between dairy intake and fertility, he said that “of all the associations we found, this is the one we had the least confidence in.” It’s also, of course, the one that made headlines.

Nearly every nutrient you can think of has been linked to some health outcome in the peer-reviewed scientific literature using tools like the FFQ, said John Ioannidis, an expert on the reliability of research findings at the Meta-Research Innovation Center at Stanford. In a 2013 analysispublished in the American Journal of Clinical Nutrition, Ioannidis and a colleague selected 50 common ingredients at random from a cookbook and looked for studies evaluating each food’s association to cancer risk. It turned out that studies had found a link between 80 percent of the ingredients — including salt, eggs, butter, lemon, bread and carrots — and cancer.”