Heart Rate: What It Is, What Affects It, and How to Audit Your Own Numbers

Heart rate is the frequency of the heartbeat measured as the number of contractions of the heart per minute (beats per minute or bpm). Heart rate varies according to the body's physical needs, including oxygen uptake and carbon dioxide excretion. When you look at your own records, you are mainly checking how quickly your heart is beating, how that changes with your daily conditions, and whether the numbers match what your devices report.

What heart rate actually measures

Heart rate is the frequency of the heartbeat measured as the number of contractions of the heart per minute (beats per minute or bpm). Heart rate is usually equal or close to the pulse rate measured at a peripheral point. When the heart is not beating in a regular pattern it is referred to as an arrhythmia.

Abnormalities of heart rate sometimes indicate heart disease. This makes careful observation of your own numbers useful, even when you are only using them to plan and adjust workouts for yourself.

What changes your heart rate from day to day

Heart rate varies according to the body's physical needs, including oxygen uptake and carbon dioxide excretion. Heart rate is modulated by factors including genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease.

Central nervous system stimulants such as substituted amphetamines increase heart rate. Central nervous system depressants or sedatives generally decrease heart rate. When you review your own records, it can therefore be useful simply to note days that include strong stimulation or sedation alongside the numbers.

Resting, sleeping, fast, and slow heart rates

The American Heart Association states the normal resting adult human heart rate is 60–100 bpm.

Tachycardia is defined as a resting heart rate above 100 bpm.

Abnormalities of heart rate sometimes indicate heart disease. When you see numbers far outside your usual pattern, recording them carefully can help you describe what you are seeing without trying to diagnose yourself.

How your nervous system controls heart rate

Heart rhythm is regulated entirely by the sinoatrial node under normal conditions.

Heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node. The accelerans nerve provides sympathetic input by releasing norepinephrine onto sinoatrial node cells, increasing heart rate. The vagus nerve provides parasympathetic input by releasing acetylcholine onto sinoatrial node cells, decreasing heart rate.

Norepinephrine binds to the beta–1 receptor. High blood pressure medications are used to block beta–1 receptors and so reduce heart rate. Cardiovascular centers in the medulla oblongata provide sympathetic and parasympathetic output that influence heart rate.

Baroreceptors detect pressure and stretch and contribute to the baroreceptor reflex that adjusts sympathetic and parasympathetic stimulation to maintain cardiac homeostasis. The atrial (Bainbridge) reflex increases heart rate when venous return stretches atrial baroreceptors. When you see your numbers rise or fall with posture, breathing, or movement, you are watching these control systems at work.

Using heart rate when you plan today’s workout

Heart rate varies according to the body's physical needs, including oxygen uptake and carbon dioxide excretion. Heart rate is modulated by factors including genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease. When you decide how hard to train on a given day, it can be useful to look at your recent resting heart rate, how you slept, and any major stresses or medications alongside these known influences.

If you have access to sleep heart rate data, you can simply note whether your numbers sometimes fall into this range, and how that lines up with days you feel more or less recovered.

The American Heart Association states the normal resting adult human heart rate is 60–100 bpm. Rather than chasing any single "ideal" number, you can focus on understanding where your own resting heart rate usually sits and how it reacts to changes in your routine.

Tachycardia is defined as a resting heart rate above 100 bpm. Recording any episodes of unusually high or low resting heart rate, together with what you were doing and how you felt, helps you keep a clear, non-interpretive log.

A simple checklist to audit your heart rate records

1. Capture a few resting measurements

Measure and record your resting heart rate for three mornings in a row under similar conditions. Try to take each reading before caffeine, work, or exercise so the numbers are easier to compare.

2. Compare device readings to a manual pulse check

Locate and count your pulse at a peripheral site and compare it to a heart rate reading from a device to see if they match. This helps you understand the relationship between heart rate and pulse rate in your own body while you check for obvious mismatches in your records.

3. Look at your sleep heart rate, if available

During sleep, heart rates around 40–50 bpm are common and considered normal, so you are mainly checking whether your data ever shows that pattern for you.

4. Log everyday factors next to your numbers

Log factors such as sleep, stress, caffeine, and exercise for a week and look for correlations with daily resting heart rate. Heart rate is modulated by factors including genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease, so a brief note beside each day’s number can make trends easier to see later.

5. Practice manual pulse skills

Practice finding and timing your pulse for 30 seconds and multiplying to get bpm to build pulse-checking skill. This makes it easier to check your heart rate in situations where you are not wearing a device.

6. Observe stimulated and relaxed states

Observe one occasion when you feel stimulated and one when you feel relaxed, then record heart rate before and after each. Central nervous system stimulants such as substituted amphetamines increase heart rate, while central nervous system depressants or sedatives generally decrease heart rate, so this exercise helps you connect subjective feelings to the direction of change you see in your own numbers.

7. If you use an app or wearable

If you use an app or wearable, compare its daily condition or score output against your recorded resting heart rate and sleep notes. Instead of treating any single score as a command, you can see how closely it follows the heart rate patterns you have measured for yourself.

8. Log unusual highs and lows without interpreting them

Tachycardia is defined as a resting heart rate above 100 bpm, and bradycardia is defined as a resting heart rate below 60 bpm, so these thresholds give you a clear way to flag outlier entries in your log without trying to diagnose them.

As a next step, pick one of the checklist items above and try it for the next three days. Treat it as an experiment: collect the numbers, note any patterns you see, and keep them alongside your workout notes so you can gradually learn how your own heart rate behaves.

This article is general health information and is not a substitute for medical diagnosis or treatment. Consult a healthcare professional if you have concerns.