How to Determine Your Target Heart Rate

Heart rate is the speed of your heart beat measured by the number of beats of the heart per minute (bpm). The heart rate can vary according to the body’s metabolic needs, including the need to absorb oxygen and excrete carbon dioxide (link to: https://en.wikipedia.org/wiki/Carbon_dioxide). It is usually equal or close to the pulse that can be measured at your wrist or can be felt by feeling the artery in your neck. Things that can influence your heart rate include activities such as exercise, sleep, emotions or medications. A normal resting adult human heart rate range from 60–100 bpm. A fast resting heart rate, defined as tachycardia, is when your heart beats above 100 bpm. Bradycardia is a slow heart rate, defined as below 60 bpm at rest. For most of us, the normal resting adult heart rate is probably closer to a range between 50-90 bpm. During sleep, a slow heartbeat with rates around 40–50 bpm is common and is considered normal.

Resting heart rate

The basal or resting heart rate is defined as the heart rate when a person is awake, in a medium temperature environment, and has not been subject to any recent exertion or stimulation, such as stress or surprise. Most experts agree that the typical resting heart rate in adults is 60–100 beats per minute (bpm). A large body of evidence indicates that the normal range is actually 50-90 beats per minute. In fact, the mortality rate of patients who are having a heart attack increased from 15% to 41% if their admission heart rate was greater than 90 beats per minute. So, your normal resting heart rate is based on the at-rest firing rate of the heart’s automatic generator which is located in the upper chamber of your heart causing your heart to beat all the time, without you even thinking about it. For endurance athletes at the elite level, it is not unusual to have a resting heart rate between 33 and 50 bpm.

Target Heart Rate or Training Heart Rate

Your target heart rate is a desired range of heart rate that is reached during exercise. This target range allows your heart and lungs to receive the most benefit from your workout by maximizing the amount of oxygen that your lungs breathe in and your heart pumps to circulate the oxygen rich blood. This theoretical range varies based mostly on age; however, a person’s physical condition, sex, and previous training also are used in the calculation. Below are two ways to calculate one’s THR. In each of these methods, there is an element called “intensity” which is expressed as a percentage. The THR can be calculated as a range of 65–85% intensity.

The formula for determining your ideal training heart rate is based first on age, then on your desired level of training intensity. It is taken into account in order to produce the most cardiovascular benefits. If your maximum is too low you can’t benefit from the training effect as efficiently.

Example for someone age 40:
(220 − (age = 40)) =180 x 65% = 117 bpm if you wish to train at 65 % of your maximum heart rate
(220 − (age = 40)) =180 x 85% = 128 bpm in you wish to train at 85% of your maximum heart rate

So the idea is that you should strive for an activity where you can train with your heart rate staying in the 65-85% range for 20-30 minutes most days of the week in order to achieve the most cardiovascular and fat burning benefits. If your goal is to burn calories, longer times of activity will help as well as working out daily. When you train in this zone of your heart rate, your body uses oxygen rich blood to break down your fat stores for fuel.

One thing to keep in mind is that if your heart rate exceeds this 85% zone, your body will switch into what is called the “anaerobic threshold” which is where you can’t breathe in enough oxygen and your heart is pumping too fast to adequately oxygenate your blood. This causes your body to convert over to“anaerobic”(or without oxygen) metabolism. The effect on your body is that alternate sources of fuel such as your muscles must be used to power your body. This anaerobic effect, if continued for more than a few minutes at a time, will result in your body breaking down muscle and creating lactic acid. When lactic acid levels in your blood rise, your body creates a more acidic environment and causes you to feel more fatigued with more muscle soreness after you exercise. The amazing thing about our bodies is that if we do“interval training”, where we cause our bodies to revert to anaerobic metabolism for short periods, we can actually enhance the training effect by teaching our body resiliency.

We create what is called EPOC or excess post exercise oxygen consumption. This idea of resiliency can come in handy when we ask our body to perform in short bursts of activity. The benefits of this activity include burning more calories at rest, developing strength, loss of belly fat and increase in beneficial hormones. So we will be prepared to sprint if we need to and be more efficient in the process. In essence, EPOC is an after-burn effect of calories burning at rest for up to 38 minutes post exercise. Eventually, we begin to experience the“training effect”which occurs when we have to work harder to reach our target heart rate because our body has become so efficient at mobilizing fat for fuel. This becomes a good thing for our body as our metabolism improves and the rate at which we burn calories even at rest increases. All of these cardiovascular and metabolic benefits are the reward for regular, frequent exercise. Our bodies are more efficient, cardiovascularly conditioned and prepared to meet that challenges of daily life, all the while burning up lots of fat stores and calories which help us to keep our weight under control.

The end result is that with steady, consistent aerobic training in your target heart rate zone, as well as interval or burst training, you will be richly rewarded with a healthy, happy efficient body. Knowing your target heart rate and the ideal training zone for your body, you will get the most of your workouts and create the best YOU possible.

So, keep up the great work and stay well until next time!!

Elizabeth Salada MD
Internal medicine and Wellness