A Case for Chiropractic Care: Do Athletes Need It?
When it comes to chiropractic care there are mixed reviews about whether it’s beneficial or a “placebo” alternative to modern-day medicine. This isn’t surprising with the lack of high-quality research to support the many claims made by members of the public or chiropractors themselves. However, if we step back and separate the false claims apart from the evidence-based treatments chiropractors can provide, there is a clear answer: everyone should be receiving chiropractic care, especially athletes. While chiropractors can provide various modalities of treatments (such as dry needling, acupuncture, myofascial techniques, etc.), for this piece, I will focus on what chiropractors are known best for: the spinal adjustment.
A spinal adjustment will most likely not be the only modality used at a chiropractic appointment. Patients can expect other treatment options to be utilized with a spinal adjustment, as well as therapeutic exercises to perform at home.
Let’s start from the beginning. What does a chiropractor do? Current research supports that chiropractors can identify segmental motor control (CSMC) abnormalities (AKA subluxation or vertebral column dysfunction) and can provide adjustments to allow for self-correcting central nervous system (CNS) responses (Haavik et al., 2021).
A CSMC abnormality involves a part of the vertebral column that is restricted or hypomobile, specifically involving a joint, that creates a snowball effect of dysfunction (Lund et al, 1991). A CSMC will first present with abnormal movement patterns to compensate for the restricted joint (in the spine these are called zygapophyseal joints), which the CNS recognizes and alters normal movement patterns to prevent injury. However, if the joint is not mobilized then the original beneficial compensation from the CNS will become maladaptive or harmful. A CSMC abnormality alters the movement of a joint, which in turn alters how the CNS perceives stimulus about where the body is in space. Therefore, high-velocity, low amplitude (HVLA) thrusts, called adjustments, are important for maintaining optimal function by reducing the time the body must compensate for a CSMC. However, this process is not as simple as it may seem.
An identified abnormal CSMC segment of the vertebral column can alter interoceptive and exteroceptive stimuli, that is to say, how a person’s CNS perceives their internal and external environment. This disrupts proprioceptors (receptors that continually give information to the CNS about where the body is in space) and changes motor control of the spine and extremities, ultimately leading to musculoskeletal disorders (Haavik et al, 2021; Meier et al, 2018).
But how does a chiropractic adjustment work to change an abnormal CSMC (Figure 1)? Let’s lay a foundation for understanding the future research discussed. There is a reason why chiropractors focus primarily on the vertebral column. As discussed earlier, proprioception is critical for efficient motor movement. Proprioception is achieved through mechanoreceptors (receptors that sense body movement, like if you’re driving a car and pushing a gas pedal, you can tell how far you have the pedal pushed to accelerate or slow down), such as muscle spindles, Golgi tendon organs, and joint receptors (Purves et al, 2001). Muscle spindles are found in our muscles (specifically skeletal muscles), Golgi tendon organs in tendons, which are what connect muscles to joints, and joint receptors are located around joint capsules. Therefore, we can see that where there is a joint, there are mechanoreceptors for proprioception.
If you’re still having difficulty understanding proprioception, think of this. If you close your eyes and try to touch the tip of your nose, you should be able to do so without accidentally touching your cheek or forehead first while finding where your nose is. Your ability to have no visual or auditory cues about where your nose is, yet still navigate your hand through space blindly and precisely touch the tip of your nose, is thanks to proprioception.
Likewise, between each vertebra, there are two facet joints on either side, which make up the zygapophyseal joints- the joints of the vertebral column. There are 43 total zygapophyseal joints in a person presenting with typical anatomical structure (some people may have an extra vertebra which could alter this number). Furthermore, 23 additional joints create the vertebral column called interspinous joints (commonly referred to as spinal discs). These joints are pictured in Figure 2.
It should also be noted that there are 40 total muscles in the back, 20 on each side of the vertebral column. The copious amounts of joints and musculature that create the vertebral column and surrounding anatomy are what make the spine ideal to adjust. These structures are what allow a spinal adjustment to cause a stimulus great enough to alter the CNS’ perception of proprioception.
The vertebral column is not the only structure that is adjusted by chiropractors. Elbows, shoulders, feet, jaws, etc. can all be adjusted as well. The spine is just the primary focus for this writing.
Now that we have established a basic understanding of why the vertebral column is essential to chiropractic care, let’s see what the research says about how a chiropractic adjustment influences proprioception. As stated previously, a CSMC abnormality alters the movement of a joint, which in turn alters how the CNS perceives stimuli about where the body is in space. This changes neural function and leads to maladaptive changes in CNS, which can be seen as poor movement patterns which contribute to neuromusculoskeletal disorders.
An example of this would be someone who has an abnormal CSMC in their lower spine (lumbar spine). Low back pain (which can be caused when a CSMC abnormality is present) has been found to alter trunk muscle activation. This alteration can lead to compensatory movements of the trunk and lead to the displacement of load (van Dieën et al, 2019). This can be seen as someone back squatting and loading their spine more than normal due to weak bracing of the trunk musculature, ultimately leading to an overuse injury. Another example of this is someone who has sprained their ankle multiple times. That ankle joint’s mechanoreceptors are now altered from a CSMC abnormality, and they now have a greater risk of spraining their ankle again due to instability and poor proprioception.
“Poor” proprioception can be seen as someone who has difficulty determining where they are in space. For example, an athlete has their eyes closed, and you ask them to point their toes in about 10 degrees and they overshoot this request and turn their toes in almost 40 degrees. This shows that they are unaware of where their foot is in space and have a decrease in proprioceptor function.
However, a spinal adjustment can create a new stimulus at the vertebral level of the abnormal CSMC and give the CNS a chance to correct its altered state. For example, a study found that a spinal adjustment increased strength in patients, as well as the patients’ ability to balance with their eyes closed (Vining et al, 2020). Likewise, another study found that spinal adjustments increased position sense and stability of the ankle joint in patients who underwent treatment for 12 weeks, which was measured on a proprioception test platform (Holt et al, 2016). Another study found that patients who had chronic neck pain and received spinal adjustments to their neck (the cervical vertebrae) had a decrease in pain and an increase in proprioception accuracy with neck and head movements (Beinert et al, 2015). Therefore, research suggests that HVLA adjustments create a stimulus to the CNS through mechanoreceptors surrounding the vertebral column through a “rapid stretch” mechanism, that ultimately improves proprioceptive acuity throughout the body (Haavik et al, 2016).
Studies show that the vertebral column is the central integration system for afferent and efferent stimulus (information coming from inside and outside the body reach the CNS after traveling through spinal structures). This is one proposed theory of how a change in the spinal column can alter the extremities as well.
But what else can spinal adjustments do? Is it just about movement? Spinal adjustments have also been found to increase strength through “feedforward activation” (Marshall and Murphy, 2006). Feedforward pertains to how the body can learn from past experiences and predict how to move more efficiently in the future. This is primarily the function of the cerebellum (the most posterior part of the brain). For example, when you are learning a new skill, such as riding a bike, it may feel uncomfortable and unnatural at first. But the more times you practice, the easier it gets. This is because your CNS has created feedforward mechanisms to predict what you need to do before you execute the movement. Your CNS has essentially created a communication system from your brain to your muscles that run whenever you do that specific activity.
Likewise, researchers have found that spinal adjustments improve feedforward activation in deep abdominal muscles (Marshall and Murphy, 2006). This means that spinal adjustments aid in the CNS creating those pathways from your brain to your muscles faster, allowing someone to learn new physical skills quicker and more efficiently. Furthermore, the mechanism of feedforward activity is also protective. The greater efficiency of postural muscles to respond to environmental stimuli, the greater the protective mechanism. For example, one study found that patients with delayed trunk reflexes (low feedforward activity) had a higher risk of low back injuries due to poor movement patterns (Cholewicki et al, 2005). Therefore, it can be concluded that feedforward activity allows for muscles to better respond to the environment.
Finally, a mechanism that functions alongside the feedforward activity is muscle recruitment. Muscle recruitment pertains to a motor neuron and all the individual fibers of muscle it innervates (this is called a motor unit). The CNS increases muscle strength by recruiting more motor units, meaning more muscles are activated in a movement. This mechanism is seen in everyday movements, such as picking up a pencil versus a 50lb dumbbell. Picking the pencil up requires fewer motor units, or less muscle recruitment, compared to lifting a 50lb dumbbell.
For example, a study performed on chronic stroke patients found that chiropractic adjustments increased plantar flexor muscle strength after one treatment (Holt et al, 2019). These are muscles that contribute to extension of the ankle, or the ability to point your toes down towards the ground versus pulling them back towards your shin (this inverse is called dorsiflexion).
Likewise, other studies have found that patients who received spinal adjustments (specifically the neck, or cervical spine) had an increase in grip strength (Gorrell et al, 2016; Botelho and Andrade, 2012). Similarly, spinal adjustments in the lower back region (the lumbar spine) have shown to increase quadricep muscle force (Grindstaff et al, 2009). Lastly, Chilibeck et al (2011) discovered that spinal manipulation could reduce muscular imbalances in strength between a patient’s hip abductor muscles (such as the gluteus medius). Interestingly, another study indicated that the change a spinal adjustment has on the CNS is like that of a 3-week strength training program (Niazi et al, 2015). Overall, it can be concluded that spinal adjustments improve muscular strength by increasing the recruitment of larger motor units.
Let’s look at a case study to further solidify the importance of spinal adjustments for efficient proprioception and increased muscular strength. A case study performed in 2004 investigated how a chiropractic adjustment could alleviate altered ankle function in a 13-year-old female who was a competitive soccer player (Gillman). The patient presented to the chiropractor with ankles that “gave out” while running or walking. This can be defined clinically as ankles that are uncontrollably inverted (caved inward) due to altered ligament proprioception (specifically the deltoid ligament of the ankle, located on the medial malleolus, or the inner ankle). This altered proprioception comes from an ankle sprain, which causes joint laxity and alters the proprioceptive receptors, increasing the delay of muscular response (Clark et al, 2013). The patient’s right ankle was found to have a reduced range of motion, weakness in musculature surrounding the right glute and hip, and weakness in the left hamstring and hip abductor muscles. Research shows that patients prone to ankle inversion can present with weak hip abductor muscles which increase the stress of the ankle to maintain proper balance (Lee et al, 2014) (Powers et al, 2017). Therefore, the focus of the treatment was increasing proprioception in the ankle joint and improving muscle strength of the weak hip abductors.
Abduction refers to any motion of a part of the body away from midline, such as standing on one leg and moving the other leg up and away from the body or performing a side-lying clamshell exercise. The primary muscles involved are the gluteus medius, gluteus minimus, and tensor fasciae latae. Other muscles involved are the piriformis, sartorius, and gluteus maximus.
The treatment included HVLA adjustments to levels of the spine that provided nerve innervation to the weak musculature and altered ankle joint. For example, joints contributing to the altered anatomical structures included the sacroiliac joints (the joints connecting your pelvis, or hip bones, to your lower spine), segments of the lumbar spine (the lower part of your spine, specifically L3), thoracic spine (the portion of the spine in the middle of your back between your shoulder blades, specifically levels T3-T5), and joints of the ankles and feet (focusing primarily on the talus bone, shown in Figure 3). By day 7 of the case study the patient had received two treatments and reported no episodes of ankle inversion. Over the course of a year, seeing the chiropractor for spinal issues or other neuromuscular dysfunction, the patient reported only 4 episodes of inversion, and by visit 17 (the last reported visit) the patient had no episodes of ankle inversion and was successfully playing soccer, lacrosse, and basketball pain free. This case study supports that chiropractic adjustments can increase proprioception and muscle strength to improve movement patterns in athletes.
This is a good time to point out that while adjustments focus primarily on spinal joints, a HVLA thrust can be applied to any joint, such as the ankle, to increase proprioception.
So why do athletes need chiropractic care? The topics discussed above show how a spinal adjustment can increase proprioception, allowing athletes to move more efficiently and safely, while also increasing an athlete’s ability to achieve their full-strength potential through the increase of greater muscle recruitment. Both outcomes allow athletes to move pain-free while also preventing future injuries. Spinal adjustments are supported by research to increase the function of the spine and ultimately allow for the CNS to correctly “predict, monitor and execute the movement of the whole body” (Haavik et al, 2021). More than anyone, athletes rely on their bodies to function optimally. Chiropractors can assist in an athlete reaching their full potential with a spinal adjustment.
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