The topic of heart rate variability is certainly not a new topic. The first observations on this phenomenon were made as early as 1700 years ago. HRV has also been used in popular sports or in training control in general for some time. So it is not surprising that many manufacturers like Garmin or Polar have already integrated HRV or stress measurements into their devices. And also here and there you hear from professional athletes* that they (again) use HRV for training control.
In summary, the topic HRV is an evergreen and has lost nothing of its importance in the last years. However, there are still athletes and trainers who have not been in contact with HRV and therefore do not know the potential added value of HRV for themselves or their athletes. For this reason, we are launching #HRV today, a new series about heart rate variability.
In this series we want to clarify what HRV actually is, which basic terms and parameters one should know and how HRV measurement and the resulting data can be used meaningfully in training planning and control.
What is heart rate variability?
A healthy heart beats unevenly and the duration between heartbeats varies. Even with a constant pulse, the heartbeats do not follow each other after a constant duration. It is precisely this variance that is called heart rate variability, or heart rate variability. The higher the variance of the intervals, the higher the heart rate variability and the more recovered, fitter and healthier the body is.
For example, for a pulse of 60 beats per minute (BPM), the interval between two heartbeats is one second on average. Now, if there were always a second between heartbeats, the heart rate variability would be zero. It would be better if the duration between the heartbeats varied. The mean would still be one second, but the variance would be much greater.
The autonomic nervous system
The autonomic nervous system (ANS) controls all biologically determined and automatically running processes in our body. All vital functions such as heartbeat, breathing, metabolism and digestion are adapted and regulated by the autonomous nervous system. HRV measurements provide a non-invasive marker to gain insight into the ANS, and thus into the inner workings of the body.
The autonomic nervous system is divided into the sympathetic, parasympathetic and enteric parts.
While the sympathetic and parasympathetic nervous systems work in mutual complement and control the most important organs, the enteric nervous system is a completely independent system. It regulates the important gastrointestinal functions completely autonomously, but is subject to the influences of the sympathetic and parasympathetic systems in order to harmonize with the whole organism.
The sympathetic nervous system
The sympathetic system ("fight or flight") ensures that we become maximally efficient in appropriate situations and is described as the most important activation system in the body.
The sympathetic nervous system makes the heart beat faster and provides increased blood supply to muscles, heart and brain. It increases the blood sugar level and at the same time inhibits other functions such as digestion, growth, kidney activity or insulin secretion. As a result, the supply is optimised, performance is increased and energy reserves are called up. On the other hand, everything that is not needed for the task at hand is inhibited in order to save valuable energy.
The sympathetic nervous system can boost the body to maximum performance.
The analysis of heart rate variability allows the measurement of parasympathetic and sympathetic activation and thus an early detection of pathogenic conditions.
The parasympathetic nervous system
As an antagonist to the sympathetic nervous system, the parasympathetic nervous system ("rest and digest") ensures that the cardiovascular system calms down again. It accelerates processes in the body that promote regeneration and replenish the energy stores.
The muscles relax, the heart rate is reduced, immune reactivity is improved, digestive activity, food intake and metabolism are stimulated and the blood supply in the skin and periphery increases.
The parasympathetic system thus ensures recovery, relaxation and restoration of strength after heavy exertion.
What exactly is fitness?
Fitness itself can not only be described by performance (sympathetic activity), but is also determined by the ability to recover (parasympathetic activity). Fitness is therefore a mixture of performance and recovery ability.
With the help of an analysis of the own HRV, the individual fitness can be determined and its development can be tracked.
As athletes* we run through cities, drive over mountains, swim through pools, lakes or seas. We want to be fit and want to know what positive or negative effects the training and the living conditions have on our own fitness. With the help of an analysis of the own heart rate variability and thus a measurement of the parasympathetic and sympathetic activation, the individual fitness can be determined and its development can be followed visually.
What factors influence HRV?
Of course, there are factors that can influence heart rate variability positively and negatively. For example, the following factors lead to a reduced HRV
- Alcohol,
- late and plentiful dinner the night before,
- Drugs,
- little or insufficient sleep,
- Diseases,
- Infections,
- intensive physical strain,
- psychological stress and
- Stress
In contrast to this
- a good regeneration,
- sufficient sleep and
- a balanced diet
increases the HRV.
What are the parameters for the analysis of heart rate variability?
There are many different parameters, some are considered indicators of parasympathetic, some indicators of sympathetic and some indicators of overall activation.
We will look at the most important parameters and their meaning in the next article in this #HRV series.
