I love the heart. It's so unique in that it has its own contractile tissue that is a different kind from skeletal muscle tissue in your body and it has its own vascular system (seen above). It's funny to think that the heart needs its own blood supply because it's the one pumping that blood! But the heart is a kind of muscle so of course it needs blood in order to work!
One of the most fascinating things about the heart is that it is the window to our nervous system.
For those that are a little fuzzy in the art of interoception, it is a great way to objectively measure, well, how are you doing??
The resting heart rate tells us how often our heart contracts while our body is in chill mode. It is best taken in the morning before you get out of bed. You can touch your carotid pulse in your neck, touch your radial pulse in your wrist, or stare at your fancy smart watch to count each beat. Count how many beats go by in 30 seconds and multiply that by 2. That gives you your beats per minute (bpm). The higher the resting heart rate, the more your heart is working. When you have good fitness, your resting heart rate is lower because it becomes more efficient as a result of training. One of the adaptations to fitness is more blood is pumped out of the heart per contraction so the heart gets to beat a little less often. But here is where it gets super cool: if you are stressed, haven't slept well, drank a few too many somethings the previous night, or are overtrained, your resting heart rate actually increases. Some even argue it's a great way to catch an overuse injury before it actually happens. If your resting heart rate is starting to increase, it's time to back off and slow down. Now of course, there are exceptions, such as various disease states, that also influence resting heart rate.
Using a heart rate monitor while doing physical activity is also very telling. As you improve your fitness, your heart rate will eventually decrease for the same work load (intensity) that used to kick your butt. For example, if you have been training your body to walk at a 15 minutes/mile pace for 30 minutes for long enough to allow for your body to adapt, your heart rate will eventually become lower during this activity than when you first began training. The same rule about stress holds true during physical activity. When we are over stressed (more than our body can adapt to) either physically, mentally, emotionally, or chemically, our heart rates will increase during a familiar work load. We all adapt to stress differently because there are many factors at play, including social support, diet, sleep, self-talk, etc.
Monitoring heart rate is the secret sauce to training and it decreases the risk for overuse injuries. The general recommendation is to keep 80% of your total work load for the week at an easy heart rate. You may have heard of Zone 2 training. If not, Google it. The other 20% of the week is used for higher intensity, such as lifting more weight or moving at a faster speed. If you're having an off day or week and your heart rate is higher than usual during what is usually an easy pace, RESPECT THE HEART RATE! Your body is telling you what you are capable of that day via your heart rate. Don't let your ego stomp all over it and push yourself to an oblivion anyway. If you are cycling at 16 mph and your heart rate is 180 bpm when it has been 170 bpm in the past, it's time to slow down. Once you are used to understanding the feeling inside your body, your interoception, during different heart rates, you can start to trust your intuition.
Heart rate monitors are relatively inexpensive these days and many watches do it on their own, although they may be slightly less accurate. Using heart rate as your guide follows the well-known wisdom of meeting your body where it is in that moment. Remember, only you can advocate for the health of your body. Listen to it.