In 2006, three researchers undertook a study looking at the effect of chiropractic adjustments on movement time [1]. They were looking specifically at Fitt’s Law – a model of human movement based on pointing and manipulation tasks involving computers. The group was small, with just ten participants. But a significant change was noted in the treatment group (who received high-velocity, low-amplitude adjustments to areas of “joint dysfunction.”) There was a significant improvement in movement time with chiropractic care, which suggested that, “spinal adjustments may influence motor behaviour.”
It was a pilot study, and it was small, but the results were noteworthy. For many it may have flown under the radar. For others, it represented a small but important contribution to the evidence that chiropractic had a place outside of pain and relief – that it could indeed help lift certain areas of human performance. Though it is now 13 years old, the study is still relatively new in terms of research. Still our understanding of chiropractic care and its benefits as they may apply to human performance has jumped ahead in leaps and bounds since then.
We have seen individual case reports, for example, covering the resolution of injuries or neuropathies under chiropractic care. This includes a recent one in which an 18-year old male presented with a cricket injury that caused pain, loss of strength, reduction in range of motion, as well as pins and needles [2]. In his case, at the end of a six-week course of care he reported:
- Feeling better, with less pain.
- Improvements in quality of life, including a significant improvement in physical functioning.
- Significant changes in range of motion, thermography, and sEMG readings after the progress examination.
- Significant improvements in posture and in previously abnormal neurological tests.
In his individual case, it is easy to see how chiropractic care could restore human movement. Of course this is but one story of human performance benefiting from chiropractic care post –injury. But could it boost human performance in a more vitalistic model of care when pain and injury aren’t the primary concern? When we look to the broader research for information on this topic, we see a clearer picture come together.
The Research Roundup
Nearly 10 years after the Fitt’s Law study was published, another paper hit the press. This time, Imran Khan Niazi and colleagues put the H-reflex and V-waves to the test, asking study participants to perform maximum contractions using leg muscles. What they found was fascinating [3, 4]:
- There was an increase of almost 60% in the electrical activity readings from specifically targeted muscles, a 16% increase in absolute force measures, and a 45% increase in the drive from the brain to their muscle.
- There was a change in the H-reflex happening at the spinal cord level, but it wasn’t a spinal cord phenomenon. The brain was changing that reflex effect.
- The participants who received chiropractic adjustments got stronger in comparison to the control group. They did not fatigue the same way.
- The effect was almost identical to three weeks of strength training.
The study presented chiropractors with some valuable takeaways: it was now clear that chiropractic care changed the structure and function of the brain. It was also clear that it could reduce fatigue and increase drive to the muscles.
This finding alone paints a picture of chiropractic care as a valuable tool for the athlete or physical labourer. But soon research would reveal the potential for chiropractic care to aid another form of labour too – that of childbirth.
Again emerging from New Zealand, the study found that adjusting pregnant women appears to relax the pelvic floor muscles at rest [5]. This was a significant finding, as the pelvic floor muscles have active roles in pregnancy and childbirth as well as spinal stabilisation. A novel finding in this study was that the control group, made up of non-pregnant chiropractic students who are adjusted often, had pelvic floor control comparable to elite athletes. Whilst this secondary finding, and its implications on pelvic floor control (and thus stress incontinence among other issues) is not yet clear, it certainly warrants further investigation.
With damaged pelvic floor muscles contributing significantly to the burden of disease worldwide, and with birth complications remaining an issue of concern for expectant mothers and their caregivers alike, the studies indication that chiropractic care may help women to have a natural vaginal delivery (via increased ability to relax the muscles the baby needs to move through in birth) was a hopeful indication indeed.
We have also seen very recent papers showing that chiropractic care for the cervical spine could increase maximal bite force, and that chiropractic “spinal manipulation” (i.e. the adjustment) shortens the cortical silent period [6, 7]. This adds to a growing evidence bank showing many non-musculoskeletal benefits of chiropractic care – from cerebellar function and sensorimotor integration to reduced falls risk and increased ability to perform mental rotation tasks [8].
The implications for individuals under care
While we are certainly a long way from research proving that chiropractic care can help athletes beat their personal bests or help academics perform at higher levels than they already do, there are some solid indications that chiropractic may have some implications in the area of human performance. It sits in the realms of hypothesis at this point, but still:
- We are increasing our understanding of how the brain drives the muscle. If the cortical silent period is shorter post-adjustment, then this means signals from the brain reach the muscles sooner.
- We know that bite force may increase post cervical-spine adjustment, and that maximal contractions to large muscles (like the leg muscles studied) increase post-spinal adjustment. Both of these have potential to impact physical and athletic disciplines.
- We also know that the increase in H-reflex happened at the brain level not the spinal cord level, and that other studies have shown changes in the prefrontal cortex (which is responsible for executive function) post adjustment.
This is slowly but surely coming together to show us the mechanisms behind why chiropractic works. We have further to go of course, but we can now see that when we adjust, we change the structure and function of the brain. We can increase some brain signals, and allow them to reach their destination sooner. We can remove distortion, which may mean less fatigue and more strength.
As we saw from our recently published consciousness series, the neuro-plastic implications of chiropractic may have many an impact on brain-related aspects of human performance. Now it is becoming clear that a well-adjusted body is one in which muscle strength and sensorimotor integration are more efficient, and fatigue may be reduced.
As our understanding of the vertebral subluxation grows, so too does our knowledge of the flip-side – what happens when we remove it. Those results are proving encouraging indeed.
References:
- Smith D, Dainoff M, Smith J (20016), “The Effect of Chiropractic Adjustments on Movement Time: A Pilot Study Using Fitts Law,” The Journal of Manipulative and Physiological Therapeutics,” Volume 29, Issue 4, May 2006, Pages 257-266, Doi: https://doi.org/10.1016/j.jmpt.2006.03.009 retrieve 4 February 2019
- Russell D, Doyle M (2018), “Resolution of lower limb neuropathy and improved physical functioning in an 18-year old male cricketer receiving chiropractic care: a case report,” CJA 46, Number 2. Pp 162-171
- Niazi, IK, Turker KS, Flavel S, Kinget M, Duehr J, Haavik H (2015), “Changes in H-reflex and V-waves following spinal manipulation,” Experimental Brain Research, April 2015, Volume 233, Issue 4, pp. 1165-1173, https://link.springer.com/article/10.1007/s00221-014-4193-5 retrieved 4 February 2019
- Staff Writer, (2016), “Greater Strength, Muscle Function and Less Fatigue,” Australian Spinal Research Foundation (Interview with Heidi Haavik), https://spinalresearch.com.au/research-project-h-reflex-and-v-waves-2/ retrieved 4 February 2019
- Effect of Spinal Manipulation on Pelvic Floor Functional Changes in Pregnant and Nonpregnant Women: A Preliminary Study. Haavik, Heidi et al. Journal of Manipulative & Physiological Therapeutics , Volume 39 , Issue 5 , 339 – 347
- Haavik H, Ozyurt M, Niazi I, Holt K, Nedergaard R, Yilmaz G, Turker K (2018), “Chiropractic Manipulation Increases Maximal Bite Force in Healthy Individuals,” Brian Sciences, 2018, 8, 76; doi:10.3390/brainsci8050076
- Haavik H, Niazi I, Jochumsen M, Ugincius P, Sebik O, Yilmaz G, Samran Navid M, Gorkem Ozyurt M and Turker K (2018), “Chiropractic spinal manipulation alters TMS induced I-wave excitability and shortens the cortical silent period,” Journal of Electromyography and Kinesiology, Volume 42 (2018), pp. 24-35
