We usually think of our pulse to be a regular beat. But, in fact, we can learn a lot from the subtle changes that occur continuously. Here are some of the key factors related to our health and wellness that we can determine by taking a closer look at our heart rate and how it varies.
Resting Heart Rate (RHR): Our pulse rate when we’re in a relaxed state is a good indicator of our overall health. A normal resting heart rate for adults ranges from 60 to 100 beats a minute. Generally, a lower heart rate at rest implies more efficient heart function and better cardio-vascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats a minute.
Our resting heart rate varies throughout the day, and usually becomes faster the more we are emotionally aroused or anxious. In these states the sympathetic branch of our central nervous system controls our metabolism. This is commonly referred to as the fight or flight mode. Our heart rate not only increases, but can become more erratic. Resting heart rate also increases when exercising to supply our muscles with more oxygen.
Heart Rate Variability (HRV): There is a very interesting link between our heart rate and breathing. When we inhale our heart rate tends to increase, and when we exhale it slows down. HRV is an excellent measure of overall fitness. Heart rate variability is higher when we are young, is usually greater in athletes and lower when we are anxious or stressed, especially over a long time. A high HRV also correlates with life expectancy.
This coupling of breathing and heart rate is emphasized more when we breathe slowly. When we breathe around 6 breaths a minute, HRV is at a maximum and said to be in the “coherent” breathing range. Slowing your breathing rate down to this low rate helps in relaxation and reducing anxiety and stress. Everyone has a unique breathing rate at which their HRV is highest, usually between 4 and 8 breaths a minute. At this rate, it is much more likely that the parasympathetic mode of our central nervous system will take over – the so-called rest and digest state, stress levels decline and we feel very relaxed.
Variations in pulse rate not directly linked to breathing can be an indication of heart problems such as atrial fibrillation and should be discussed with a physician.
Resting Breathing Rate (RBR): By monitoring HRV, it is possible to derive the underlying breathing rate that is modifying the pulse. The normal breathing rate for an adult at rest is 12 to 20 breaths per minute. Exhale times are about 1.5 inhale times. Just like RHR, the lower RBR, generally the fitter you are. Athletes may have an RBR around 8 per minute. RBR is higher in babies and pre-teens and tends to increase with age in adults. Training to promote periods of RBR around 6 minute can help stress reduction.
Vagal Balance: Our highly complex body is kept functioning efficiently under widely varying physical and emotional conditions by a central control system continuously running in the background. Heart and breathing rates vary, our digestive and cooling functions modify when needed etc. The control system has two distinct modes – the sympathetic “fight or flight” and the parasympathetic “rest and digest” as differing responses to changes. To maintain excellent health these two branches need to be in balance – at a so-called good “vagal tone”. It is possible to extract indicators of this balance by digging deeper into the finer structure of HRV. Specifically by examining the frequency components of HRV and looking at how much emphasis is being focused on different components it is possible to determine how far out of balance our central nervous system might be.
Recovery from Breathing Interruptions: When our breathing is interrupted, either voluntarily by holding our breath, or unwittingly, as in sleep apnea, the vital oxygen in our blood becomes depleted. Normally our blood is saturated with oxygen when leaving our lungs to a value of about 98% of full capacity. When breathing is interrupted, after a few seconds or so, the oxygen content begins to decline perhaps to a dangerous level of about 90%. Our pulse rate then begins to increase in an effort to get more oxygen to vital organs. But at the same time, the strength of our pulse may weaken as the heart is now being starved of oxygen. Fortunately our central control system triggers us to breathe before suffocating. Once we return to normal breathing, there is a recovery time for the pulse rate to slow down while regaining its full power. Changes in pulse rate and strength associated with breaks in breathing are different from normal HRV and can be used to determine how resilient our cardio-pulmonary system is to interruptions. A higher resilience has been shown to help with asthma control, reduction of snoring and sleep apnea symptoms and even in helping in nicotine withdrawal. Resilience can be increased with appropriate training.
The BreatheSimple patented system is able to measure all of the above factors using just the camera on a mobile phone – an easy way to monitor key factors underlying overall health and wellness, and to keep track of improvements.