Chiropractors talk a great deal about sports performance, but we tend to leave the autonomic nervous system out of this discussion. We need to correct this.
This post was inspired by reading through Dr. Andrew Flatt’s blog www.hrvtraining.com. This website is a treasure trove of information on the topic of the autonomic nervous system, heart rate variability, adaptation, and exercise physiology. Every paper and abstract I have written on this topic has referenced at least one of Dr. Flatt’s papers.
This quick post will be somewhat of a commentary about Chiropractic and sports performance while highlighting a few gems I pulled from two articles on his blog. The first article is one I shared on our Facebook page on May 1 titled: “If you’re not assessing (the ANS) you’re guessing,” and the second one is “HRV Explained Part 2: the Research.”
As a side note, the title of the first paper applies to Chiropractors in a big way. I can’t remember where I read it, but I remember coming across a line in a text book several years back that told Chiropractors that if we are going to stake our claim on the nervous system, that we need to own it by understanding the anatomy, physiology and how to evaluate it. I don’t think I can overstate this enough. Heart rate variability is at the forefront of assessing function of the ANS (especially when it comes to athletes), yet very few chiropractors are utilizing it as an objective measure.
I want to use this post to put a little more context into how HRV is being used to assess performance. Before I begin, let me declare that this type of research is in it’s infancy, and consensus is a long ways off. Most exercise physiologists in the field are saying that HRV is a good means of assessing adaptation to training stress but must be considered in the context of subjective outcomes including psychometric variables and, of course, performance. Don't take this blog post to mean that HRV is the end all be all. It is a great tool, but not the panacea of sports performance (more on that later). I’m going to scratch the surface on this topic in this post, but if you want more info head over to the hyperlinks I posted above and spend a few hours (or days) perusing Dr. Flatt’s website.
HRV Used to Assess Recovery Status
Chen et al in 2011 utilized Heart rate variability to assess recovery status in a small sample of olympic weightlifters, and found that a return to baseline was correlated with baseline performance (1)
Pichot et al used HRV to assess fatigue and found a decrease in parasympathetic tone and an increase in sympathetic tone in response to overload training (2).
HRV to Predict Performance
Cipryan studied hockey players and noted a correlation between HRV scores and a coaches assessment of performance. Athletes who had higher HRV scores (parasympathetic) were more likely to have performed better according to coaches.
Buchheit et al utilized HRV to assess endurance performance and concluded that it was useful in assessing training response and possible a predictor of performance (4).
These are only a few studies of hundred potential studies out there that discuss this topic. Again if you want more info and insight from someone I consider to be the leader in this field of exercise physiology check out www.hrvtraining.com and get lost in that blog for a few days. He has done some fantastic work and does a great job of compiling his thoughts in one place.
As I stated before, this field of work is in it’s relative infancy, and the use of HRV in predicting performance has a long way to go. A review of the literature in 2008 stated that HRV is a useful tool but must be used in the context of further subjective markers as well (5).
HRV in physiology and pathology research
Aside from the interest in heart rate variability in the exercise physiology arena, HRV is being investigated in terms of its applications in pathology and physiology. I refer to one of the great researchers in this field, whom I have had the pleasure of listening to and meeting on several occasions, Yori Gidron PhD.
In 2006, Gidron wrote about the role the Vagus nerve plays in potentially modulating an anti-inflammatory response as well as an afferent function of “informing” the brain about peripheral inflammation (6). Keep in mind that heart rate variability is utilized to assess vagal function as it relates to the cardiovagal autonomic relationship.
In 2013, Gidron investigated data on 5 different cancers (n=657) and found prognostic value in assessing HRV and vagal function (7).
These studies and many more lend to the context in which HRV is being investigated for diagnostic, prognostic, and overall physiologic means. Perform a search of Yori Gidron in google scholar or
and just start reading. The research that is being conducted and published is fantastic.
Comments About Sports Chiropractic
The role of Chiropractic and sports is largely a injury diagnosis and rehabilitative role. While many Chiropractors excel in this field, I believe we need to shift our focus at the very least to utilizing HRV as an means of assessing autonomic response in our athlete patient population. We have begun using heart rate variability in our office this past year, and I have been experimenting with it in our athlete patients for quite some time. While I feel the data I have collected has more clinical relevance than it does scientific relevance (small sample size, lots of variables), I have seen some very interesting correlates.
In order for us to effectively investigate autonomic responses to Chiropractic care and athletes, I believe we need to start by investigating an acute response to the adjustment in athletes. Simple pre and post HRV readings in athletes. Interestingly, there have been several studies that have done that in non-athlete patient populations (8,9,10). Once we have established a body of evidence related to acute responses to the Chiropractic adjustment, the next step would be to follow a population of TRAINED athletes undergoing a training program. We should assess HRV in a group of athletes under Chiropractic care compared to a control group, and correlate with measures of performance and psychometric questionnaires such as the REST-Q. I emphasize a population of trained athletes for a couple reasons. 1) Untrained athletes will improve performance no matter what. An untrained athlete will undergo short term adaptations and improve performance in an almost linear fashion. An athlete who has been undergoing training for several years will have reached a point where performance improvements become far more difficult. 2) an untrained athlete will have far more erratic changes in subjective outcomes (pain, fatigue, etc) and will likely have far less clinically significant shifts in HRV readings day to day, due to the fact that a training stimulus will be a novel stress to their body and they have not undergone the typical adaptations a trained athlete has.
Where do we go from here?
First, we have to explore the ANS and it’s relationship to not only Chiropractic but also to performance. As this field continues to grow (at a very rapid pace) our profession can not be left behind. As I said before, if you head over to www.hrvtraining.com and browse articles and studies that are continually coming out, you will see how vast this body of evidence is becoming. Second, it is very simple to utilize HRV in our offices. Ultra short HRV readings are becoming increasingly validated and accepted in the sports physiology arena. In our practice, we have been utilizing 2 minute readings looking at rMSSD and HR in the first week a patient is under care, and the week leading up to their final re-exam. So far this data has given us some great clinical value, but until we refine our methodologies we haven’t produced much statistical significance (yet). In order to develop this as a common practice protocol, we need our profession, it’s governing bodies, and it’s educational institutions to recognize the value of HRV and begin to teach it to every Chiropractic student as we continue to develop our collective understanding of it.
When it comes to sports performance and Chiropractic, I don’t believe we need to change the conversation, however, we should introduce a new side bar to the conversation. As exercise physiology and strength and conditioning continue to evolve their paradigm to understanding adaptation, our profession should be paying very close attention to the evidence looking at the nervous system and performance. Chiropractors view the spine and it’s intimate relationship to the nervous system as central to our professional identity. The anatomic and physiologic foundation has been laid for us to begin investigating HRV as an outcome measure and the relevance it would have to performance and athletes is coming to the forefront.
1) Chen, J., Yeh, D., Lee, J., Chen, C., Huang, C., Lee, S., Chen, C., Kuo, T., Kao, C., & Kuo, C. (2011) Parasympathetic nervous activity mirrors recovery status in weightlifting performance after training. Journal of Strength and Conditioning Research, 25(6): 1546-1552
2) Pichot, V., Busso, T., Roche, F., Gartet, M., Costes, F., Duverney, D., Lacour, J., & Barthelemy, J. (2002) Autonomic adaptations to intensive overload training periods: a laboratory study. Medicine & Science in Sports & Exercise, 34(10), 1660-1666.
3) Cipryan, L., Stejskal, P., Bartakova, O., Botek, M., Cipryanova, H., Jakubec, A., Petr, M., & Řehova, I. (2007) Autonomic nervous system observation through the use of spectral analysis of heart rate variability in ice hockey players. Acta Universitatis Palackianae Olomucensis. Gymnica, 37(4): 17-21.
4) Buchheit, M. et al (2009) Monitoring endurance running performance using cardiac parasympathetic function. European Journal of Applied Physiology, DOI 10.1007/s00421-009-1317-x
5) Bosquet, L. A. U. R. E. N. T., et al. "Is heart rate a convenient tool to monitor over-reaching? A systematic review of the literature." British journal of sports medicine 42.9 (2008): 709-714.
6) Gidron, Yori, et al. "Vagus–brain communication in atherosclerosis-related inflammation: A neuroimmunomodulation perspective of CAD." Atherosclerosis 195.2 (2007): e1-e9.
7) De Couck, Marijke, and Yori Gidron. "Norms of vagal nerve activity, indexed by Heart Rate Variability, in cancer patients." Cancer Epidemiology 37.5 (2013): 737-741.
8) Welch, Arlene, and Ralph Boone. "Sympathetic and parasympathetic responses to specific diversified adjustments to chiropractic vertebral subluxations of the cervical and thoracic spine." Journal of chiropractic medicine 7.3 (2008): 86-93
9) Budgell, Brian, and Barbara Polus. "The effects of thoracic manipulation on heart rate variability: a controlled crossover trial." Journal of manipulative and physiological therapeutics 29.8 (2006): 603-610.
10) Zhang, John, et al. "Effect of chiropractic care on heart rate variability and pain in a multisite clinical study." Journal of manipulative and physiological therapeutics 29.4 (2006): 267-274.