Heart rate variability (HRV)

Biostrap can, among other things, measure heart rate variability (HRV) - and measure it over a longer time, to create a more accurate and reliable pattern.

Simply put, HRV is the time difference between two successive heartbeats. The variations between consecutive heartbeats in the moment length of peaks assist us to calculate HRV. 


HRV, which is also known as  ‘cycle length variability’, ‘RR variability’ and ‘heart period variability is a reliable marker for physiological factors that directly affect heart rhythms. It reflects the heart's ability to adapt to changing circumstances - stress, exercise and disease - by balancing the regulation of the autonomic nervous system which controls body functions such as breathing, heartbeat and digestion. An elevated heart rate variability is related to good health and elevated levels of fitness. A lower heart rate variability can be an indication of many health related issues such as hypertension, diabetes, obesity, and other cardiovascular issues.


Chronic stress can seriously affect general health and productivity and can be easily seen in HRV data. Restoring equilibrium in such circumstances is essential for a healthy lifestyle.


Athletes use HRV to assess their efficiency due to the immediate effect of physical activity on variation in heart rate. Chronic overtraining often leads to physiological and psychological symptoms that weaken performance and may delay full recovery for weeks or more.

Monitoring heart rate variability gives us thorough insights into strength and fatigue.


How does it work?

HRV describes fluctuations in continuous heart rate intervals for an average pulse over a period of time. HRV is particularly affected by the autonomic nervous system which includes the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).

  • SNS mobilizes the body's hormones and nerves to quickly respond to exercise, stress and "combat situations", allowing a person to respond quickly in, for example, dangerous situations. Here, the heart rhythm becomes very regular, with a lower HRV as a result.

  • Conversely, PNS has a slowing effect on heart rate, which helps the body save energy. This system plays a major role in the body's attempts to establish equilibrium, including digestion and glandular activity. Here, the heart rhythm becomes more aware for the ongoing body processes and a bit irregular, leading to a higher HRV.


Clinical applications of HRV analysis

HRV measurements are non-invasive and most reliable when performed under standardized conditions. Research suggests that low HRV is a negative result of cardiovascular disease, diabetic neuropathy, high blood pressure and heart attack. HRV is also useful for observing people with diabetes which can cause severe dysfunction in the autonomic nervous system. Low HRV may point to the onset of diabetic neuropathy, a complication of diabetes mellitus characterized by widespread degradation of small nerves in the sympathetic and parasympathetic nervous systems.Smoking and alcohol consumption also affect HRV. Smokers have a lower HRV, possibly a direct effect of how smoking degrades the circulation regulated by the autonomic nervous system. It has also been shown that people who drink alcohol have a significantly lower HRV value than the ones that are non-alcohol dependent.


Clinical centers, academics, researchers, and physicians around the globe use HRV's heart rate variability: 

  • For predictive analysis: HRV can support the probability of future illnesses such as diabetes or heart-related issues and illnesses.

  • For assessment of medical conditions: HRV can assist to determine distinct medical circumstances such as anxiety, stress, anger and other heart associated issues 

  • By athletes: Athletes can measure their fitness levels and track their over-training as well. A substantial decrease in their HRV implies a body that is stressed or over-strained.

  • To determine fitness objectives: HRV can be used  to train the body efficiently and to attain fitness objectives.

How Biostrap shows HRV

Biostrap utilizes the overnight heartbeat for HRV assessment, as this provides most data on recovery for choices in stress, mental and physical condition and lifestyle. It provides an overview of the current HR variability but also last week, month and year. Biostrap determines a baseline in the first few days afterwards, it demonstrates what the baseline is and how HRV fluctuates compared to this.

Your daily HRV

The daily HRV is shown in rMSSD that stands for' Successive Differences Root Mean Square.' Research strongly promotes rMSSD and is considered to be the Autonomic Nervous System's most suitable and accurate measure of short-term activity. The greater the number, the more reserves someone has for the remainder of the day. Otherwise there is the baseline below and the percentage of how it differs from the baseline. Then there is a plot showing all the measurements, the ones in blue are taken during the night, the white during the day. The red line indicates the rate of recovery, the steeper down, the better the recovery was. Below the plot is the average HRV and the highest and lowest historical value.

Your HRV trend

The weekly, monthly and yearly shows the nocturnal HRV in milliseconds. The plot gives insight into the rate of variability of the heart rhythm, the desirable range, a rolling 7 days average and significant changes. Below, there is a number called ‘CV’ which stands for ‘Coefficient of Variation‘ which is calculated merely as the standard deviation (of the HRV information) divided by the mean HRV value and expressed as a percentage. In short, CV is a measure of how well one adapts to training, typically with  a lower percentage meaning better adaptation. The highest and lowest value of variability in heart rate is also displayed.

Your wellbeing

Reduced HRV has been shown to be a mortality predictor after myocardial infarction. A variety of other health conditions and circumstances, including congestive heart failure and diabetic neuropathy, may also be correlated with altered (generally reduced) HRV. Please always consult your doctor or any other qualified health professional should you have any concerns. 

Please note: Biostrap is not intended to diagnose, treat, mitigate, cure, or prevent any disease or condition.