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Crick and Crack... What the heck is that? Adjustment?

It is quite fascinating to me when a patient says: I just want a crack! It always gets the better of me, and I go for my good old fashion dad’s joke: we are not a crack house!

Bad jokes aside, as a chiropractor I have seen (and heard) a lot of misconceptions about chiropractors and what is an adjustment and more importantly how does it really impact the body. So, stick with me if you want to avoid the danger of hearing more of my dad’s jokes.

In short, a chiropractic adjustment is a small movement to a joint that is administered really quickly.

There is a reason for this quick movement, and that is to stimulate a certain receptor that is activated with that particular movement. Now, the by-product of adjustment is the ‘crack’ that you may sometimes hear. Yet, it is important to understand that crack (although sounding satisfying ) in itself is not the therapeutic component of adjustment. For example, some people are more prone to cracking than others, so judging the quality of your adjustment but the sound of a gas being released from the joint space certainly merits a dad’s joke!:)

Now that you know what annoys your chiropractor, let’s focus on what excites them and that is a small, fast and precise movement. When this type of movement occurs, certain areas of the brain a.k.a the ‘computer’ are stimulated, and it is these changes that bring all the good stuff. So, what are the good stuff, you might ask?

I am glad that you asked!

  1. Change in muscle tone: adjustments help to reduce muscle tension in the area surrounding the adjustment. This is thought to occur because during an adjustment the brain receives lots of signals from the affected area. The brain then sends signals back down to the area telling the muscles to relax.

  1. Change in proprioception: which is the body’s awareness system and the change in pain pathway regulation. Adjustments help to reduce pain and improve movement in the affected area. For example, for someone with low back pain, the muscles and joints in their back will be sending lots of signals to the brain that the brain perceives as painful. During the adjustment, the brain receives new signals from the treated area. The new signals effectively override the old signals that the brain interpreted as painful. Due to this, the brain stops perceiving the initial signals as painful. The effect of this is decreased pain and improved movement.

Moreover, some adjustments can have an impact on certain parts of your nervous system, (1) like switching OFF the sympathetic nervous system. But before we dive into that here is a quick guide to your Sympathetic nervous system, and why it is important to have a well regulated Autonomic nervous system. Then, we will discuss why we do not want our nervous systems to be switched ON all the time.

For example when your sympathetic nervous system - the one responsible for the“fight or flight” response, is activated it increases energy expenditure and stops digestion. Here is the list of the following changes that take place upon activation of the sympathetic nervous system:

  • Heart rate and cardiac muscle contractility increase

  • The pupil becomes dilated for the betterment of far vision.

  • Bronchodilation of the lungs, for quick breathe and fast air

  • Decreased GI motility, you really don’t need your digestion to be taking up energy when the energy needs to be directed toward other organs for survival

  • Decreased urine output, cause there's too much else going on

  • Increased secretions from sweat glands

  • Increased blood flow to muscles, for the big fight or the big run

  • Dilation of coronary arteries

  • Constriction of large arteries and large veins

  • Increased metabolism

  • Increased glucose production and mobilisation by the liver

  • Suppression of the immune system, because your body cares not for bugs/viruses, but to survive the bigger threat.

All these changes in your body are designed to enhance your movement and strength. “Stressful situations that threaten survival or exercise are just a few examples of increases in sympathetic nervous system activity.” (2)

On the other hand we have good old fashioned parasympathetic nervous system, also known as “rest and digest”. This system functions in opposition to the sympathetic nervous system. This includes:

  • A decrease in heart rate and contractility of cardiac muscle

  • Constriction of the ciliary muscle and the pupil for near vision

  • Increased secretion by lacrimal glands and salivary glands

  • Increased gut motility, bronchoconstriction of the lungs

  • Contraction of the detrusor muscle with the relaxation of urethral sphincters

  • Glycogen synthesis by the liver

  • Swelling of the clitoris and erection of the penis

  • Activation of the immune system

As you can imagine, having an overactive Sympathetic nervous system (fight or flight) can affect the sleep cycle, due to the body being unable to switch off as it perceives itself being under threat. Correspondingly, studies have shown that when we’re deprived of sleep the sympathetic nervous system activity increases. (3)

Last month being sleep month, and us here at Balanced for Life talking more and more with our patients about their sleep, it was surprising to hear how many do really struggle. So, facilitating the body's transition to the parasympathetic state (rest and digest) is the best thing you can do to calm your body and mind down. And now that you know that certain chiropractic adjustments can stimulate your rest and digest system you should not be surprised that our patients often report that after they have had a chiropractic adjustment that they sleep better for some time afterward.

To conclude, the chiropractic adjustment can help much, much more, but if you are struggling to sleep, and your nervous system is too fired up, taking an all rounder approach can help, and adjustments can be an important part of it.

  1. "The acute effects of joint manipulative techniques on markers of ...." Accessed 26 Feb. 2021.

  2. "Physiology, Autonomic Nervous System - StatPearls - NCBI ... - NIH." 1 Jun. 2020, Accessed 26 Feb. 2021.

  3. "Short sleep duration as a risk factor for hypertension: analyses of the ...." Accessed 26 Feb. 2021.


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