FirstBeat Bodyguard 2


Our health is dependent on the day-to-day lifestyle choices we make ourselves. It is generally accepted that exercise and enough sleep contribute to recovery, enabling us to combat stress. Together with healthy food, limited use of alcohol, these contribute to our general well-being. Stress, poor sleep quality, absence of sport engagement, overweight and obesity all increase morbidity as mortality rates. The combination of environmental factors (responsibilities at work, family and social obligations, personal financial situation and life events) and our lifestyle compose the stress factors we need to cope with on a daily basis. Short-term stress is good, it is a natural reaction (fight or flight). However, long-term stress increases the risk for disease and lowers our life expectation. Unfortunately, it is hard and difficult to quantify stress.

The autonomic nervous system

This is the counterpart of our central nervous system, which is determined by our will. The autonomic nervous system controls our organs and consists of the sympathetic and the parasympathetic nervous systems.

The sympathetic nervous system prepares our body for reaction. It’s run by adrenaline, which increases our heart-rate and blood pressure. The parasympathetic nervous system is involved in recovery, getting our body to resting levels.

Positive stress provides energy "to get the job done". Negative stress results in negative emotions and reactions. In both cases the autonomic nervous system is activated and stress hormones are produced, raising our heart rate. Sympathetic activity occurs during the day, while parasympathetic activity rules the night during sleep.
Although there is still an ongoing debate on the exact definition of stress in the international literature, we can say that stress is characterized by less recovery and dominace of sympathetic activity.

Heart rate variability (HRV)

There is a natural variation in our heart rate. This fluctuation between two successive heart beats is called the heart rate or HRV.
During stress the sympathetic nervous system increases both our heart rate and contractability. Cardiac output increases by 2-3 fold. On the other hand, during recovery the heart rate is lowered as well as the HRV.
The HRV method is useful to investigate the relationship between both nervous systems and is internationally accepted to evaluate the activity of the autonomeous nervous system.
Studies show that higher HRV levels are associated with lower mortality and morbidity rates and with higher levels of well-being and quality-of-life.

Factors influencing HRV negatively:

  1. Acute stress lowers HRV, both during sleep as well as during the day
  2. Overtraining in athletes, heart rate remains too high and HRV drops
  3. Heavy exercise
  4. Obesity
  5. Posttraumatic stress & burn-out
  6. Alcohol
  7. Shortage of sleep & jetlag


During three successive days (72 hrs) the patients wears the Firstbeat bodyguard 2 (see photo) on the chest, during day and night. Thee bodyguard detects stress when the sympathetic nervous system dominates en measures recovery when the parasympathetic nervous system is in dominance. Physical activity and inspanning are measured when breathing frequence and oxygen consumption increase.

During 72 hours, all heart rates are counted and stored. Thee data are uploaded to the Firstbeat server in Helsinki, Finland. The data passes a filter to remove false-detected or premature heart beats. Subsequently, data is segmented in time.
Physical activity is detected by accelerometer and the increased oxygen consumption. When the calculated oxygen consumption > 30% of the VO2 max it is noted as physical activity. Recovery takes place when the parasympathetic nervous system dominates. The heart rate is low and the HRV is high and uniform. This phase occurs during our sleep.

If no physical activity is detectable and neither recovery, we speak of stress. In this phase heart rate is high and HRV is low.


This mathematical analysis of the HRV data looks at the time between two successive heart beats and takes the square root of that amount. RRMSD stands for Root Mean Square of the Successive Differences. De RRMSD is an indicator for the activity of the 10th brain nerve, the nervus vagus, part of the parasympathetic nervous system. A low RRMSD value is indicative for stress.

Recovery Index (RI)

This second mathematical analysis of the HRV data described the relationship between the duration of both stress and recovery during sleep and in relation heart rhythm and breathing rate.


How does this benefit you?

The lifestyle rapport, which is derived from the data set, provides you with insight in your daily stress level and your daily recovery. It helps to find the right balance between work, social engagements, family life and the way your body recovers. The graph below shows how the subject
experiences daily stress reactions and recovers during sleep at night (green). In three successive days, this subject is able to build his resources through good sleep.

The HRV method is very suitable to measure both the quantity as well as quality of sleep.

Do the test and gain insight in your stress and recovery levels.  A healthy balance between stress and recovery is important for your health, keeps you more fit and younger!


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