The HRV (heart rate variability) - Everything you need to know!
As an active athlete or someone interested in health, you hear more and more often about the so-called heart rate variability (HRV). But not only laymen are increasingly interested in HRV, the number of scientific articles is also constantly increasing:
What is heart rate variability?
HRV describes the change in the intervals between every 2 heartbeats. It is measured in milliseconds (i.e. one thousandth of a second). The greater the variability (that means, the more different the individual distances are from each other), the better. Here you can see how HRV is calculated from an ECG:
Why is greater variability better?
Without deeper knowledge, one would assume that it is good for the heart to beat as evenly as possible. In truth, however, just the opposite is true - but why? Every person has a multitude of sensors in their body that provide important feedback for the control of the heart to optimally supply the entire body with blood. The vegetative nervous system is then used to influence the heartbeat in its sequence. If this influence works well, a strong variation of the heartbeat intervals occurs and indicates relief. If this fine control functions poorly or barely, then the organism is under strain.
You want even more detailed information? Check out our webinar on the basics of heart rate variability here:
History of HRV
The first documented use of heart rate variability dates back to the Chinese physician Wang Shu-ho in the 3rd century AD who recognized even then that a very regular heartbeat indicates poor health. He recognized, "If the heartbeat is as regular as the knock of the woodpecker or the drip of the rain on the roof, the patient will die within 4 days." At that time, the delicate intuition of an experienced physician was necessary to recognize this condition. Today, 1700 years later, there are extremely accurate HRV measurement devices for this purpose.
Application areas of heart rate variability
HRV is primarily used in two areas: sports and health:
Training according to HRV
To align your training according to your heart rate variability it is necessary to measure it dailyat least 2x. For this, it is almost mandatory to use an HRV meter that calibrates to your body. HRV values are highly age and person dependent. Only with a device that is calibrated can you be sure that training recommendations are also accurately matched to your body. On days when your heart rate variability is high, you can train anything from light regenerative sessions to intense intervals to strenuous strength training. If your HRV is low, then you should do light to no training, depending on how low it is. Good apps will show you this in an understandable way.
Detect overtraining by HRV - is that possible?
Yes, it is - if you perform at least one measurement daily. You can recognize overtraining by regeneration values that don't recover. Good HRV apps show you this - here's an example from the Vitalmonitor portal:
Overtraining from mid-October. The solution: more recovery time or less load.
HRV as a stress indicator
In health management, heart rate variability is used to measure the stress level. Most often, this is also done using a calibration phase, as the stress resistance of different individuals varies greatly. Good HRV apps use a mixture of the heart rate variability itself and a breathing exercise for this. This determines how long it takes the organism to adapt the heartbeat to the breathing cue (the faster and stronger the coupling of the heartbeat to deep breathing works, the more recovered the organism is).
BioAge as a measure of lifestyle
Another common value is the BioAge. It tells how well one's HRV values compare with others. The lower the heart rate variability, the higher the biological age. The essential thing to remember is that you can lower BioAge through exercise/sport, diet, rest & time management (check out a blog article on Lowering BioAge here).
The Biofeedback is about measuring biological processes and thus also "training" them at the same time. Essentially, it is the targeted learning of the activation of the parasympathetic nervous system(sympathetic and parasympathetic nervous systems are two counterparts in the body. The sympathetic nervous system can be compared to an accelerator pedal - the parasympathetic nervous system is the brake). Measurements are again taken with an HRV measuring device. The biofeedback exercises show:
By measuring and getting feedback on your body's functions through heart rate variability, you can learn to influence them. Through regular biofeedback exercises, you can increase your HRV and strengthen your stress resistance.
Factors influencing HRV
The following factors lead to greater or lesser heart rate variability:
Improvement of heart rate variability
After describing what factors influence HRV it is relatively easy to improve heart rate variability. The possibilities are divided into 4 main groups:
- Exercise/Sports: Whether exercise or sports right away depends on the initial situation. Overweight people, for example, should start with exercise or light swimming training first to avoid damaging their joints. For all (hobby) athletes: Attention an intensive endurance or strength unit increases a possible stress load (with intensive load the same hormones are released as with stress). This can also disturb sleep.
Nutrition: Improving HRV is also possible with a healthy, balanced diet. Rapid improvement is promised by the following measures:
- eat clearly before going to bed
- Fruit and vegetables 5 times a day
- Replace juices with water (juices often contain large amounts of sugar)
- abstain from alcohol
- Pay attention to the ingredients of the food
- Recreation: The majority of human rest is accounted for by sleep. Important factors here are the time of falling asleep, the duration and depth of sleep, and screen time (smartphone, tablet, TV, laptop) before going to bed. However, recovery stimuli can also be provided during the day through relaxation exercises. Examples of this would be yoga, autogenic training or biofeedback exercises, etc.
- Time management: Learning to make the best use of time can also improve heart rate variability. To do this, it is important to clearly delineate free time and working time, to clearly fix the workload, to avoid multitasking if possible, and to structure and prioritize work. This reduces stress and allows for better use of recovery time.
Which HRV value is good?
This depends on several factors. Basically, heart rate variability decreases with age. How this looks approximately is shown in the following graphic:
However, one's HRV can be strongly influenced by life style as described earlier. How this can look like is shown in the following graphic:
The BioAge always indicates how good one's own HRV values are for the average age. If the biological age is higher than the actual age, then one has worse heart rate variability values than usual for the age. It is the same the other way around.
What devices are available for measuring HRV?
In principle, there are several different ways to measure heart rate variability, which have different advantages and disadvantages:
Floor standing units
This class of device usually has a built-in ECG and thus a high accuracy. With floor standing devices, mostly short term measurements are performed. Another advantage is that they are supervised by a professional partner who explains complicated HRV values. Disadvantages are very high costsfor such a device and thus high costs per measurement, since each measurement must be performed and interpreted by a partner. Moreover, a single measurement has little significance, since it depends very much on the condition of the day.
These devices have the advantage that they are usually cheaper than other HRV stand meters. Meanwhile, they even reach almost the accuracy of ECG stand devices. In this class of devices there are 2 subcategories:
- a partner is necessary for the evaluation & declaration
- the statements depend on the condition of the day.
- The daily routines are similar and therefore rarely surprising (HRV is usually good in the morning, stress decreases it, eating decreases it, during exercise it is decreased, relaxation exercises increase it, sleep increases it).
What is the cost of HRV measurement?
The cost is strongly related to the measuring device used. A one-time measurement (24h HRV) with a supervisor costs approx. 150-300€/measurement. If you buy your HRV measurement device with app, the cost drops to less than 1€/measurement after one year of use. In addition, you have the constant monitoring of HRV values and not just the picture from one day.