Heart rate 51 on an adult - what does it mean?

Where 51 bpm sits on the adult scale

What a resting pulse of 51 means

A pulse in the 50s at rest is typical for people who exercise regularly, and for most adults first thing in the morning. Large population studies associate lower resting heart rates — within the normal range — with better cardiovascular fitness.

It matters only if it comes with symptoms such as unusual tiredness, dizziness, shortness of breath or fainting, or if it is a new change for you without a training explanation.

Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 51 bpm the heart beats about every 1.18 seconds — roughly 73,440 beats a day.

A runner’s or cyclist’s 51

Ask a group of regular runners, cyclists, rowers or triathletes for their morning pulse and plenty will answer with a number in the low 50s. Resting rates of 40 to 60 are common in people who train for endurance, and 51 sits comfortably in that spread.

Some elite endurance athletes go even lower and rest below 40, but that is rare. Recreational athletes who train a few hours a week more often land in the 50s, and many of them watched the number fall from the 60s or 70s over their first years of training.

The reason is a set of adaptations sometimes called “athlete’s heart”. Repeated long efforts make the heart’s main pumping chamber slightly larger and better at filling, so each beat moves more blood. At the same time, the parasympathetic side of the nervous system, which slows the heart, becomes more dominant at rest. The body needs the same amount of blood per minute as before, so it gets there with fewer beats.

Signs the low 50s reflect fitness

An endurance athlete’s slow resting rate usually comes with a few other traits:

• the pulse rises promptly and smoothly when a run or ride begins
• it reaches high values in hard intervals without a struggle
• it falls quickly after stopping, often by more than 12 beats in the first minute
• the resting value dropped gradually as training built up and rises a little during long breaks

Fast recovery after effort is worth noting, because a drop of less than 12 bpm in the first minute after hard exercise is a recognised marker of worse outlook. A trained heart typically does much better than that.

When even an athlete should check

Being fit does not rule out a heart problem. Talk to a doctor, ideally one familiar with sports cardiology, if any of these appear:

• fainting or near-fainting during or right after exercise
• chest pain or pressure while training
• performance falling away for weeks without a training or illness explanation
• a pulse that suddenly races, stutters or will not climb during efforts

A morning pulse that jumps several beats above your usual 51 for a few days is a different signal. It often means fatigue, a coming cold, alcohol or poor sleep, and it is a common reason athletes take an easy day. Chest straps give the most reliable training data; see heart rate monitors for how they compare with wrist sensors.

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.

Nearby values

• 46 bpm
• 47 bpm
• 48 bpm
• 49 bpm
• 50 bpm
• 52 bpm
• 53 bpm
• 54 bpm
• 55 bpm
• 56 bpm

Measured on a child instead? See heart rate 51 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.