Why Is My Resting Heart Rate So High? 9 Notable Causes Explained

Most runners are well aware that your heart rate during exercise can provide an indication of your aerobic fitness as well as the intensity level of your workout.

For these reasons, wearing a heart rate monitor while you run or using a GPS watch with wrist-based heart rate monitoring has become increasingly popular amongst recreational competitive runners alike. 

While capturing your exercise heart rate data can certainly be a useful metric to track to gauge your fitness progress and the effectiveness of your workouts, it can also be beneficial to monitor your resting heart rate. Looking at that data, some may be wondering, why is my resting heart rate so high?

With the advent of fitness trackers that can easily quantify biometrics like heart rate 24 hours a day and sync the data to your phone, many runners are already recording their daily resting heart rate even if they’re not regularly reviewing the data.

In this guide, we will talk about the significance of your resting heart rate, factors that affect your resting heart rate, the normal resting heart rate for adults, and answer the very important question: “Why is my resting heart rate so high?”

We will look at: 

  • What Is Resting Heart Rate?
  • How Do You Measure Your Resting Heart Rate?
  • Factors That Affect Resting Heart Rate
  • Why Is My Resting Heart Rate So High?

Let’s get started!

A person looking at their heart rate monitor wondering, why is my resting heart rate so high?

What Is Resting Heart Rate?

Your resting heart rate refers to the number of times your heart beats in a minute when you are at rest. 

When you are lying down and in a calm and relaxed state, your muscles and other tissues require significantly less blood and oxygen than when you are exercising. Therefore, your heart does not need to pump as much blood so your heart rate is lower than when you are up and about.

According to the American Heart Association, the normal resting heart rate for adults is typically between 60 and 100 beats per minute, though it tends to be lower in runners and other endurance athletes, due to physiological adaptations from consistent training. 

Research suggests that a higher resting heart rate is associated with an increased risk of adverse cardiovascular events and all-cause mortality. 

How Do You Measure Your Resting Heart Rate?

There are a couple of methods you can use to measure your resting heart rate. 

A person on a beach adjusting their heart rate monitor.

Heart Rate Monitors

On the technology side of things, you can use a chest strap heart rate monitor or a wrist-based heart rate monitor to measure your resting heart rate. Chest strap heart rate monitors use electrodes to detect the electrical conductivity signals of your heart as it contracts (beats) to pump blood. 

Much like the electrodes used on an electrocardiogram (ECG), the electrodes of chest HR monitors are sensing the spike on the ECG (called the QRS complex) when the left ventricle contracts and pumps blood out of the heart through the aorta into circulation. 

In contrast, wrist-based heart rate monitors use optical heart rate sensing in a process known as photoplethysmography (PPG) to detect your heart rate. 

PPG uses flickering light (usually in the form of green LED lights) and special light-sensitive diodes to measure your heart rate. 

The LED light penetrates your skin and reflects off your blood. The degree to which your blood absorbs or reflects light varies according to whether your heart is contracting (beating) or relaxing in between beats.

The light-sending diode registers these two variations in light absorption, integrates the data in the device with an accelerometer (which measures movement), and feeds the data through an algorithm to yield a heart rate value based on the number of times these fluctuations occur per minute. 

Two people measuring their heart rate.

Manual Pulse Detection

You can also manually measure your resting heart rate by palpating your pulse and counting the number of times you feel your pulse.

The most common sites to measure your pulse are on the inner surface of your wrist and your carotid artery on the side of your neck. You can also put your hand over your heart, though this can be a difficult area if you have significant breast tissue or muscle mass overlying your chest.

Although you can count the number of beats in an interval of 15 seconds and then multiply your answer by four to get the number of beats per minute, it is more accurate to continue counting for the entire minute. 

This differs somewhat from the recommendations for measuring your heart rate during and after exercise. Your heart rate during vigorous physical activity is more sensitive to changes in intensity level. 

Therefore, if you stop exercising or end a hard interval and want to capture your pulse at that high rate, it makes more sense to count the number of beats you feel at your pulse site over a short interval (like 15 seconds) and then extrapolate that number to a full minute rather than actually count for a full minute while you rest. 

A person with two fingers on their wrist, measuring their heart rate.

This is due to the fact that your heart rate will continue to slow that entire minute, skewing your estimation for how high your heart rate was while you were still pushing your body.

In contrast, your resting heart rate should be relatively stable. It’s just more accurate to measure it for the entire minute because a 15-second data capture can overestimate or underestimate depending on where in your heart cycle you start and end the time. The degree of inaccuracy will be higher if your resting heart rate if your heart is beating slowly.

Regardless as to the measurement method, you can improve the accuracy of your resting heart rate by measuring first thing in the morning at the same time every day, before getting out of bed.

Taking your readings at this time will help ensure you are capturing the truly relaxed state before elevating your heart rate as you move around, and will allow your measurements to be conducted more consistently.

It’s particularly important to measure your resting heart rate before doing any kind of exercise, smoking a cigarette, or drinking coffee or tea. Nicotine and caffeine are both stimulants, so they can increase your heart rate. 

A person on a beach measuring their heart rate.

Factors That Affect Resting Heart Rate

So, if you are wondering, why is my resting heart rate so high, there are several factors can affect it. Some of these factors may affect your resting heart rate relative to someone else’s, while others can affect your resting heart rate from day to day. 

The primary factors that affect resting heart rate include the following:

#1: Genetics

Your personal genetic makeup can influence your resting heart rate, such that two people who are the same age and health status can have a difference of up to 20 beats per minute in their resting heart rate attributable to genetic differences.

#2: Age

In general, resting heart rate decreases after infancy through childhood such that toddlers and younger children have a higher resting heart rate than older children, teens, and adolescents.

Resting heart rate tends to stabilize after maturity and remain relatively constant until age 40 or so, after which point, it trends upward with aging. 

A person with their head in one of their hands, stressed out.

#3: Smoking Habits

If you are wondering to yourself, why is my resting heart rate so high, and you smoke, you may have your culprit.

Evidence suggests that people who smoke regularly usually have a higher resting heart rate than non-smokers. Nicotine is a stimulant, so it increases heart rate. 

Moreover, smoking can cause adverse changes to the heart, lungs, and blood vessels. For example, smoking causes the veins and arteries to constrict and lose some of their elasticity, which reduces the efficiency of the cardiovascular system.

To compensate, the heart has to work harder and beat faster to effectively pump enough blood and oxygen to the tissues of the body.

#4: Stress

Physical, mental, and emotional stress can all trigger the sympathetic division of the autonomic nervous system, or the “fight-or-flight” response. This can increase heart rate and respiration rate. As a result, both chronic stress and acute stress can cause an elevation in your heart rate, including your resting heart rate.

A person running in a parking garage.

#5: State of Mind

In addition to your stress levels, your current state of mind or emotional presentation can influence your resting heart rate. For example, anxiety, excitement, surprise, and fear can all increase your heart rate.

#6: Exercise Habits

Physical activity strengthens the heart and lungs. The heart is a muscle, and as the heart gets stronger, like other muscles in the body, it is able to contract more forcefully. 

When the heart contracts more forcefully, stroke volume increases, which means that the heart is able to pump more blood—and thus oxygen—out to the rest of the body every time it beats. This can effectively reduce resting heart rate because the heart becomes more efficient.

#7: Temperature and Environmental Conditions

In hot and humid conditions, your heart has to work harder to cool your body down. The heart beats faster to bring more blood to the surface of the skin and produce sweat to help drop your core temperature. Therefore, your resting heart rate can be higher on hot days.

In much the same way, if you have a fever or are sick, your resting heart rate will be higher because your heart has to work harder to cool you down.

two people hydrating after exercising.

#8: Hydration Status

Dehydration can increase your resting heart rate because as your body water drops, your blood plasma level decreases. When you have less blood moving through your circulatory system, your heart has to pump faster to maintain your core temperature and deliver enough oxygen and nutrients to the body.

#9: Medications

Certain prescription and over-the-counter medications can affect your resting heart rate. For example, beta blockers have a tendency to lower your heart rate while certain stimulants and psychoactive medications can increase resting heart rate.

Why Is My Resting Heart Rate So High?

Now that we’ve covered the primary factors that affect resting heart rate, it’s easy to see that there can be several potential causes to answer your question, why is my resting heart rate so high?

A person looking at their phone after running.

If you smoke, are dehydrated, under chronic or acute stress, or in a warm climate, chances are your resting heart rate is going to be higher than normal.

However, for runners, there’s an additional factor that can influence your heart rate—your training status. 

During recovery from exercise, your sympathetic nervous system has to work harder to restore homeostasis. Your heart beats faster to circulate enough reparative oxygen and nutrients to your skeletal muscles to repair damage and promote recovery. 

The hormonal profile after a workout lends itself to a higher heart rate, as hormones like epinephrine (adrenaline), which are produced during physical activity stimulate an increase in your heart rate.

When you are fully recovered from a run or workout, resting heart rate returns to baseline because your tissues have received adequate perfusion and your hormones should have returned to resting levels. 

The recovery from a workout typically takes a couple of hours, depending on the intensity and duration of your workout, your nutritional status, sleep, hydration, and overall training level. 

A person on a treadmill.

However, when you are overtrained and under-recovered, this recovery process gets drawn out. Chronic overtraining can leave the body in a state of incomplete recovery, which can be reflected in a higher resting heart rate.

Therefore, if you are training hard but all other aspects of your health and life are relatively stable, a high resting heart rate can be indicative of overtraining.

A sudden increase in your normal resting heart rate can also be a sign that you’re getting sick and your heart is working harder to stave off illness.

With this in mind, monitoring resting heart rate can be a valuable practice for runners and can provide a window into your training status and potential need for more rest.

If you are in need of a heart rate monitor, you can take a look at our information regarding the top heart rate monitors on the market.

A person looking at their watch while exercising.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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