The RSA Response and How We Can Use it to Measure and Improve Health
RSA is the abbreviation for respiratory sinus arrhythmia. This is where the sinus rate increases with inspiration and decreases with expiration. RSA is not an abnormal rhythm and is most common in young healthy people. When phasic changes in sinus rate are not related to the respiratory, non-respiratory sinus arrhythmia is accentuated. Non-respiratory sinus arrhythmia is more common in older people and those with an underlying cardiac diseases.
In simpler terms, RSA occurs when a person’s heart rate relates with their breathing cycle. This means that when a person breathes in, their heart rate increases. Consequently, when the person breathes out, the rate decreases. As mentioned, RSA is more prevalent in children than in adults.
The P-P interval is the time between each heartbeat. In most people, the P-P slightly varies between 0.16 seconds and less. However, in respiratory sinus arrhythmia, the interval is a little bit longer than 0.16 seconds when the person breathes out. Take for instance exercising. During exercise, the heart rate rhythm becomes more regular as the heart speeds up.
RSA and health
Researchers may not know the exact cause of RSA but they believe that it occurs to increase efficiency or to allow the heart the heart to do less work while simultaneously maintaining the correct levels of blood gases. It is thus widely accepted that the loss of RSA can be an indicator for cardiovascular disease. On the other hand, the prominent presence of RSA indicates a healthy cardiac system.
RSA has the physiological function of matching ventilation and perfusion in the lungs and thus optimizing oxygen uptake and removal of carbon dioxide. RSA may also play a role in minimizing the energy expenditure of the heart while keeping arterial carbon dioxide levels at physiological tensions.
RSA as a measure of health
Respiratory sinus arrhythmic is used as an index of cardiac vagal tone. It also contributes to heart rate variability. HRV is a useful indicator of several health-related issues. It is a measure which indicates the variation in your heartbeats within a specific timeframe. A high HRV means that your heart is keeping the blood flowing and maintaining an ideal blood pressure at a lower heart rate. It is therefore the reason why high HRV is an indication of not only cardiovascular but also overall health and general fitness. HRV reacts to changes in the body even before the heart rate, making it a very sensitive tool that gives insights into your wellbeing.
Since RSA contributes to HRV, it helps to improve the variability of the heart rate and your overall health.
Why does RSA response decrease with age?
RSA decreases with age because aging is associated with changes in sympatho-vagal balance, with a significant increase in sympathetic nervous system outflow to the cardiovascular system in old age.
The research into the workings of the RSA response is continuously carried out in order to provide a better understanding into why it happens and why it is important. But one thing that is for certain, RSA can be used to measure and improve health.