While it is not entirely new, Heart Rate Variability (HRV) is certainly gaining popularity in the sports communities. But what is it exactly?
While for many years I have believed that each heartbeat is pounding regularly inside my chest, that is not the case. When you use a heartrate monitor, your heartbeat is shown as a number. This number is an average of all your heartbeats during a given time. The HRV is simply the time difference between each successive heartbeat, otherwise known as the R–R interval. The time between each heartbeat is not consistent, it varies with every beat – therefore the term heart rate ‘variability’.
For years, HRV has only been seen on medical equipment like a ECG. But with recent developments in sports technology, you now can use apps on mobile phones together with certain sports watch. As for now, Polar and Suunto has technology that is well configured for measuring HRV. Several others exists and more will come.
In sports, some new arenas is emerging out of measuring HRV. Your HRV gives critical information of the function of your Autonomic Nerve System (ANR). The physiology behind this is rather complex, and in my PhD projects I am now in the process of learning much more about this. Generally speaking, an increasing HRV value represents a better recovery and stress status, while a decreasing HRV value represents stress and a worse recovery status. As you can see, this can be crucial information for athletes. While this is not always the case, the golden rule is that a high HRV value represents a fitter and better recovered athlete.
The Autonomic Nerve System is in control of your involuntary responses, like your heartbeat, bladder functions, airways and more. ANS is divided into two divisions, the Sympathetic and the Parasympathetic division. They work in opposite directions. As an example, the Parasympathetic system slows the heartbeat, while the Sympathetic system is increasing the heartbeat. And here lies one of the keys to understand HRV.
HRV is affected by numerous other physiological phenomena, including hormones, your respiration, physical activities, mental load and cognitive processes, stress and more. So there are much more to learn about HRV yet. But for now, HRV is used by scientist, coaches and athletes to monitor stress and recovery. Several new research projects are within my extended research family – see this exciting project about Yoga and stress by Tiril Elstad – http://yoscience.com/2016/11/07/theyogasciencestudy/
I promise to come back when I learn more about this exciting topic!