Heart Rate Variability - How it can measure your response to stress.

What is Heart Rate Variability (HRV)?

Simply put, it’s the measure of the variation in time between heartbeats, controlled by our old friend, the Autonomic Nervous System (ANS). The more healthy your ANS is, the higher your HRV. A normal, healthy heart does not tick evenly. There is constant variation in the milliseconds between heart beats. It’s not the same as the number of heart beats measured in a minute which increase and decrease according to our level of activity. A standard measure of HRV for adults could range anywhere from less than 20 to greater than 200 milliseconds between heartbeats.

If you feel your pulse on your wrist while taking a few deep breaths, you will notice that the interval between beats gets longer as you exhale and shorter as you inhale; a phenomenon known as respiratory sinus arrhythmia. In addition to breathing, HRV is influenced acutely by exercise, hormonal reactions, metabolic processes, cognitive processes, stress and recovery.

Given that HRV is controlled by the ANS, is makes sense to ensure that this branch of your nervous system is healthy which is where Yoga comes in. By varying your respiratory rate, you improve the response of your ANS. For example, Kapalbhati is sympathetic in nature; it arouses the sympathetic nervous system because of it’s rapid rate. Conversely Ujjayi stimulates the parasympathetic nervous system when the exhalation is elongated. While Alternate Nostril Breathing is considered a balancing breath for the ANS.

People who have a high HRV (greater variability between heart beats) are more responsive to changes in the ANS. High HRV means your body is capable of responding to changes in its internal and external environment and is more likely to return quickly to a state of equilibrium.

Poor sleep quality, high levels of stress, an unhealthy diet, lack of exercise, loneliness or dysfunctional relationships cause us to be in a persistent state of sympathetic arousal (fight and flight) and are likely to lead to low level HRV.

How can you improve your HRV? The best way is to vary your activities. Here are a few examples:

• Yoga (specifically breathing practices)

• Aerobic exercise

• Meditation

• Saunas

• Cold showers or sea swimming

Practice a little Yoga at regular intervals rather than a long practice just once a week. As American Yoga Teacher Mary Richards says,

“A little Yoga goes a long way,”