Heart Rate

Heart rate is the number of times the heart beats in one minute, usually expressed in beats per minute (bpm). In healthy adults at rest, a typical heart rate is about 60–100 bpm.​

Normal ranges

• Most adults: resting heart rate 60–100 bpm when awake, calm, and not moving.​

• Well‑trained endurance athletes can have resting heart rates around 40–50 bpm because their hearts pump more efficiently.​

• During moderate to vigorous exercise, it is common for heart rate to rise into the 120–160+ bpm range depending on age, fitness, and intensity.​

What affects heart rate

Heart rate goes up or down in response to the body’s demand for oxygen and blood flow. Important factors include:​

• Physical activity and fitness level

• Emotions and stress or anxiety

• Illness, fever, dehydration, and body temperature

• Medications, caffeine, alcohol, nicotine, and some drugs

• Hormones, weight, sleep, and underlying heart or thyroid disease​

When to be concerned

• Resting heart rate consistently above 100 bpm (tachycardia) or below 60 bpm (bradycardia) in a non‑athlete may indicate a problem, especially with symptoms.​

• Seek urgent or emergency care if an abnormal heart rate is accompanied by chest pain, shortness of breath, fainting, severe dizziness, or sudden weakness.​

• Over the long term, higher resting heart rates (especially above about 80–90 bpm) have been linked to increased risk of cardiovascular events and earlier mortality.​

How to check your heart rate

• Place two fingers (not your thumb) on the radial pulse at the wrist or on the side of the neck where an artery is close to the skin.​

• Count beats for 30 seconds and double the number to get bpm, or count for a full 60 seconds for more accuracy.​

• Many wearables and phone-based sensors can also estimate heart rate, but manual checking is useful for confirmation.​

If you share your age, resting heart rate, and whether you measured it at rest or during activity, a more tailored interpretation can be given.

LOW HEART RATE:

A low heart rate is usually defined as fewer than 60 beats per minute at rest and is called bradycardia. It can be normal and healthy in some people, but in others it can signal a problem with the heart’s electrical system or other medical issues.​

When low is normal

• Many fit or athletic people naturally have resting heart rates in the 40s or 50s without any symptoms; in that case it is often considered a normal variant.​

• Low rates during sleep can also be normal as the body’s demand for oxygen falls.​

Possible causes

• Heart electrical issues: sinus node dysfunction, heart block, sick sinus (tachy‑brady) syndrome.​

• Heart damage: aging, prior heart attack, cardiomyopathy, myocarditis, congenital heart defects, or prior heart surgery.​

• Non‑cardiac: hypothyroidism, electrolyte imbalances (potassium, calcium, magnesium), obstructive sleep apnea, some infections, certain medications (for blood pressure, arrhythmia, etc.).​

Symptoms to watch for

Low heart rate is more concerning when the heart cannot pump enough blood to meet the body’s needs. Common warning signs include:​

• Fatigue, weakness, or getting tired very easily with activity.​

• Dizziness, lightheadedness, confusion, or difficulty concentrating.​

• Shortness of breath, chest discomfort, or feeling that the heart is “pounding” or irregular.​

• Fainting or near‑fainting episodes; these are urgent warning signs

HIGH HEART RATE:

A high heart rate means the heart is beating faster than normal, usually defined as more than 100 beats per minute at rest in adults; this is called tachycardia. It can be normal during exercise, stress, or illness, but when it is high at rest or associated with symptoms, it may indicate a problem.​

Normal vs high

• Resting heart rate for most adults is about 60–100 beats per minute; above 100 at rest is generally considered high.​

• During moderate to vigorous exercise, heart rate commonly rises into a target zone of roughly 50–85% of your age‑predicted maximum (about 220 minus age), which can be 120–160+ bpm depending on age and fitness.​

Common causes

• Physiologic: exercise, fever, pain, anxiety, dehydration, caffeine, nicotine, alcohol, some medications, and anemia can all raise heart rate.​

• Heart‑related: supraventricular tachycardia, atrial fibrillation, atrial flutter, inappropriate sinus tachycardia, ventricular tachycardia, heart failure, or prior heart damage.​

• Hormonal/metabolic: overactive thyroid (hyperthyroidism), low blood pressure, low oxygen, and some endocrine disorders.​

Symptoms to watch for

• Palpitations (racing, pounding, or fluttering), feeling “out of breath” more than expected, chest discomfort, or reduced exercise tolerance.​

• Dizziness, lightheadedness, fainting or near‑fainting, sudden weakness, or new confusion are more serious warning signs

Seek help for heart rate issues based on both the number (high or low) and how you feel. Any fast, slow, or irregular heartbeat that is new, persistent, or causing symptoms deserves medical attention.​

Call 911 / go to ER now

Get emergency care immediately if you notice an abnormal heart rate (fast, slow, or irregular) and ANY of these:​

• Chest pain, pressure, or discomfort

• Trouble breathing or shortness of breath at rest

• Fainting, near-fainting, or sudden severe dizziness

• New confusion, trouble speaking, or sudden weakness

• Heart rate extremely high (for example, 150–160+ at rest) or feels “out of control”

• Heart rate very low (around or below 35–40 bpm) with feeling unwell

Author

Paddy Kalish OD, JD and B.Arch Author and Blogger