Heart rate 31 on an adult - what does it mean?
A resting heart rate of 31 bpm is very low for an adult. Outside of elite endurance athletes and deep sleep, a pulse under 40 is unusual: see a doctor promptly, and call 911 (US) or your local emergency number if you feel faint, have chest pain or are short of breath.
Where 31 bpm sits on the adult scale
- Very low
- Low (bradycardia)
- Slightly low
- Normal
- Elevated (tachycardia)
- High
- Very high
What a resting pulse of 31 means
Very slow resting rates in people who are not highly trained can mean the heart's electrical system is not keeping pace — for example sinus node dysfunction or a heart block — or can be a medication effect (beta blockers, some calcium channel blockers, digoxin). An underactive thyroid, low body temperature and electrolyte problems are other causes.
Rule out a measuring error first: a weak or irregular pulse is easy to undercount by hand, and some wrist wearables miss beats. Count for a full 60 seconds at the wrist or use a chest-strap or blood-pressure monitor.
Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 31 bpm the heart beats about every 1.94 seconds — roughly 44,640 beats a day.
When the upper and lower chambers stop talking
A pulse of 31 in someone who is not asleep and not an elite athlete raises one particular question for doctors: is the electrical signal getting through? In a healthy heart, the sinus node at the top fires, the upper chambers (atria) contract, and the signal passes through a small relay station, the AV node, to the lower chambers (ventricles) that do the real pumping.
In complete heart block, also called third-degree block, that relay fails entirely. The atria keep beating at their own normal pace, perhaps 70 or 80 times a minute, but none of those signals reach the ventricles. To keep blood moving, a backup pacemaker lower down takes over. Backup sites are slow. A rhythm starting near the AV junction often runs around 40 to 60, and one starting in the ventricles themselves often runs 20 to 40. A steady pulse near 31 fits that second picture.
How it shows up and how it is found
Because the backup rhythm is slow and cannot speed up much, people often notice:
- tiredness and breathlessness on stairs or slopes
- dizziness, or sudden collapse with little warning
- a pulse that stays slow even when they walk briskly
- new confusion, particularly in older adults
A standard ECG usually settles the question in minutes. It shows small atrial waves marching at one rate and wider ventricular complexes at another, with no fixed link between them. Doctors call this AV dissociation.
Common causes include age-related scarring of the conduction system, a heart attack, heart surgery, and medicines that slow conduction. Some causes are reversible, such as Lyme disease, very high potassium or a drug that can be stopped under supervision.
Why treatment is usually a pacemaker
Complete heart block that is not due to a reversible cause is one of the clearest reasons for a permanent pacemaker. The device senses the atrial signal and delivers a matching beat to the ventricles, restoring a normal rate and the ability to speed up with effort. While waiting, hospitals can pace the heart temporarily.
If your reading of 31 comes with fainting, chest pain or severe breathlessness, call 911. If you feel well, still get an ECG today. More background on how the heartbeat is generated is on the human heart rate page.
31 bpm during exercise
31 bpm is below half of the estimated maximum heart rate at every adult age, so it is a resting-range value, not an exercise intensity. During light activity most adults are already above 90 bpm.
For a reliable resting value, sit quietly for five minutes first and average a few mornings: Resting Heart Rate: What It Says About Your Health. You can also measure by tapping along on the start page.
Check another reading
Nearby values
Measured on a child instead? See heart rate 31 in a child.
Sources: American Heart Association: All About Heart Rate · MedlinePlus: Pulse · ACSM position stand on exercise intensity (2011)
This page explains a single reading in general terms. It is not a diagnosis. Heart rate alone cannot tell whether the rhythm is regular or whether the heart is healthy — if you are worried, talk to a doctor.