LEARNING FROM THE ATHLETES
You will have seen athletes wearing heart rate monitor watches and chest straps before, and anyone can use this technology to optimize, analyze and monitor performance with the help of what is called heart rate variability (HRV). The same process can also be used to measure stress and the ability to recover in terms of burnout. But don’t worry: this does not mean you have to go around wearing a chest strap all the time. All you need to do is measure your HRV using the HRV app we recommend. You then enter the values when filling out our stress questionnaire as part of the BURNOUT Risk Test.
JUST WHAT IS HRV?
ECG showing RR intervals. The R wave is the most distinctive wave in an ECG. The heart rate, or pulse, is inversely proportional to the RR interval; therefore, a lower heart rate means a longer RR interval, and vice versa. HRV is calculated by measuring the difference in the distance between two R waves, i.e. the heart rate.
Not many people know this, but our heartbeats are never absolutely regular. A pulse, or heart rate, of 60 beats per minute does not necessarily mean that the gaps between successive heart beats are exactly one second long. Sometimes the gap will be 0.845 seconds long, then 0.745 seconds, 0.812 seconds and so on. You can see this more clearly in the electrocardiogram (ECG) below:
The large R waves in the ECG are never exactly the same distance apart (RR distance) – this time interval represents the heart rate variability, measured as the root mean square of successive differences (rMSSD).
Put simply, HRV is the spontaneous rhythm of the heart, or heart rate – it shows the heart’s ability to adapt to, and perform in, different situations.
The greater the fluctuation in these distances from an individual base value (the resting pulse), the better an individual is able to cope with physical and psychological strain, such as that caused by stress. This means the less regular your heartbeat is, the higher your HRV and the easier it is for your body to shift up or down a few gears. An irregular heartbeat in a healthy heart is therefore a clear sign that you are fit and healthy, while a rhythm that is too fixed, or low HRV, is a sign that something is amiss. Your heart beats more regularly during the hours and even days following intense and frequent physical and psychological strain – low HRV can thus be a clear symptom of stress and excessive physical activity.
THE HRV CURVE SHOWS YOUR STRESS LEVELS
Unlike blood pressure, there is no standard or threshold value for HRV, meaning there is no way to determine exactly how high it should be – it all depends on the individual. Yet despite this, when it comes to stress, the following still applies:
“High heart rate variability indicates a great capacity for dealing with stress, and a high level of individual resistance. Low heart rate variability, however, is a sign of exhaustion, resulting from prolonged periods of strain, and shows a low level of resistance.”
MEASURING HRV IN COMBINATION WITH THE BURNOUT RISK INDEX STRESS QUESTIONNAIRE AND BRIX™ STRESS LAB TEST
How do you find out your HRV? Either from your doctor, or by using an HRV stress tracker. However, it is important to be sure that HRV is measured accurately and is not influenced by an unreliable measuring device. HRV measuring devices work by using a “sensor”, meaning you require either an ear or finger clip or a chest strap. We recommend the KUBIOS HRV App with the Bluetooth Smart Heart Rate Monitor H7/10 from Polar.
Please note: apps that claim to measure your HRV simply by using your smartphone’s camera (photoplethysmography) are only able to deliver limited values in terms of accuracy for measuring heart rate variability (rMSSD).
It is important that you always measure your heart rate variability (HRV) at the same time of day and in the same position. You should measure the HR and the heart rate variability (rMSSD) exactly for 1 minute (Settings) after you have remained still for a period of at least five minutes. Please also note that illness, nicotine, alcohol or lack of sleep may influence the HRV values.
Every time you fill out the BURNOUT Risk Index Stress Questionnaire we recommend that you also measure your heart rate variability (rMSSD) at the same time and enter the values into the BURNOUT Risk Index Stress Questionnaire.