Fitness technology is evolving rapidly and heart rate variability (HRV) is at the forefront of a wave of new tech gadgets that are poised to change the way we monitor fitness.

WHAT IS HRV?

HRV is not a new concept, this is actually a technology that has been commonly used in research for 40+ years. But it's only in the last decade, really the last 2-3 years, that the technology has become cheap, portable and reliable enough to allow us to take this technology out of the lab and place it into the hands of the personal trainer and fitness consumer.

In the early days HRV testing required an electrocardiography machine (ECG/EKG) which could easily cost $10,000 or more. However, advancements in tech now allow us to accurately measure HRV using commercially available equipment such as a Bluetooth-enabled heart rate monitor and a smart phone app that can be as little as a few dollars (several apps are even free).

HRV testing is a very sensitive and non-invasive tool that is capable of providing us with important insight into the autonomic nervous system. While that sounds very technical (and in some ways it is), it is also quite simple. Let me explain with an analogy: when you look at your smart phone or computer you are presented with a very simple interface. For example, on your smart phone you likely have an icon that is shaped like a musical note; when you tap on this icon it opens up your whole musical library. What you don't see, however, is the very complex code that is actually running in the background that allows this simple interface to occur. In the human body the autonomic nervous system is that "complex code" running in the background and it automatically takes care of everything so you don't have to give it any conscious thought. Your ability to sweat, digest food and increase your heart rate to deliver more oxygen to working muscles are all examples of the autonomic nervous system at work.

The autonomic nervous system is like a barometer of your internal environment and provides a reflection of your overall health and fitness. When your internal environment is under stress (such as after an intense workout, a sleepless night or psychological stress) this will be reflected in your HRV scores. Therefore, one of the more common ways that HRV is used is as a daily tool to guide your workouts (or the workouts of your clients). When your HRV is high, that’s an indication that today is a good day to push your limits. Conversely, when your HRV is low that suggests it might be a good recovery day.

However, decreased HRV is also associated with a long list of diseases such as heart disease, COPD and PTSD, but none more so than type 2 diabetes. In fact, HRV scores have been shown to be depressed in people with pre-diabetes1, indicating that HRV may be an early indicator of poor glucose control. Importantly, though, the autonomic nervous system (and HRV) responds to exercise in much the same way as the cardiovascular system or muscles; it becomes more robust and "stronger." While diseases such as type 2 diabetes have been clearly shown to decrease HRV, consistent exercise has been shown to increase or restore HRV levels.2

HRV testing represents a technological leap in our ability to monitor the physiological status of ourselves and our clients. HRV testing is useful across a diverse range of client populations, from elite athletes to cardiac rehab patients, and most everyone in between. There is, however, one noteworthy exception and that will be anyone that is taking heart rate-altering medication, such as a beta blocker (commonly prescribed for hypertension). Since HRV is a measurement derived from the heart rate anything that alters or changes that will also change the HRV score.

Carmine R. Grieco, PhD, CSCS is a personal trainer with over 15 years training experience, Carmine successfully made the transition from personal trainer to university professor in 2012. Currently an Assistant Professor of Kinesiology at Colorado Mesa University, Carmine is a past West Virginia state director for the National Strength and Conditioning Association (NSCA) and also holds certifications as a yoga teacher, exercise physiologist and health coach.
References
Singh JP, Larson MG, O’Donnell CJ, Wilson PF, Tsuji H, Lloyd-Jones DM and Levy D. Association of hyperglycemia with reduced heart rate variability (The Framingham Heart Study).American Journal of Cardiology 86: 309-312, 2000.
Routledge FS, Campbell TS, McFetridge-Durdle JA and Bacon SL. Improvements in heart rate variability with exercise therapy.Canadian Journal of Cardiology 26(6): 303-312, 2010.

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