Heart rate (HR) is a simple, free window into how hard the body is working. For swimmers and coaches it is used for three things:
Intensity. Is this set easy aerobic work, threshold work or all-out? HR gives a body-based measure that sits alongside pace and stroke rate.
Fitness over time. As aerobic fitness improves, the same pace is usually done at a lower HR, and HR recovers faster after effort.
Readiness and fatigue. A morning resting HR that is well above a swimmer's normal is a common early sign of fatigue, illness or poor recovery.
HR is one tool, not the answer on its own. Use it with pace, stroke rate, how the swimmer feels (RPE), and where available lactate testing — see A Guide to Lactate Testing.
02
How to take your pulse
Wrist (radial): turn the palm up, place the first two fingers on the thumb side of the wrist, just below the base of the hand. Press lightly.
Neck (carotid): two fingers beside the windpipe, under the jaw. Light pressure, one side only, never both sides at once. Often easier right after hard effort.
Use fingertips, not the thumb (the thumb has its own pulse and causes miscounts).
Count each beat from the moment a stopwatch starts. Call the first beat "zero", then count 1, 2, 3 and so on.
How long to count
Count for
Multiply by
Use it for
60 seconds
×1
Resting HR (most accurate)
30 seconds
×2
Resting HR when short of time
15 seconds
×4
Pre-set or recovery checks
10 seconds
×6
Immediately after a set — HR falls fast, so count short
Shorter counts magnify any miscount: one missed beat in 10 seconds is a 6 bpm error. Practise with the pulse-count tool (section 7) until counts are consistent.
03
When to take it
Tap each moment to see what to do and what it tells you.
04
Working out your zones
Step 1 — find a maximum heart rate (HRmax)
Estimate:220 − age is the common rule; 208 − 0.7 × age (Tanaka) is usually a little better, especially for older swimmers. Either can be 10 bpm or more out for an individual.
Measure: the best source is the highest HR actually reached in a hard, well-warmed-up swim test, ideally supervised by a coach.
Step 2 — find resting HR (HRrest)
Average of 3–5 mornings, taken lying down before getting out of bed.
Step 3 — apply the heart-rate-reserve (Karvonen) method
Target HR = HRrest + % × (HRmax − HRrest)
Using the reserve rather than a flat percentage of HRmax makes zones fit the individual — a fitter swimmer with a lower resting HR gets a wider range.
Zone
% of reserve
What it is for
1 Recovery
50–60%
Warm-up, warm-down, active recovery
2 Aerobic base
60–70%
Easy continuous swimming, technique, volume
3 Aerobic endurance
70–80%
Steady aerobic sets, long open water pace
4 Threshold
80–90%
Hard sustained efforts near race-pace endurance
5 Maximal
90–100%
Short, fast repeats and sprints
These bands are a common guide, not a fixed rule. Coaches may adjust them for the individual, the season and the goal.
05
Swimming is different
Swimming HR is usually lower than the same effort on land. The body is horizontal, supported by the water, and cooled by it, so the heart does not have to work as hard to return blood. A commonly quoted difference is roughly 10–15 bpm lower at maximum, varying between swimmers and strokes.
That means a land-based estimate like 220 − age tends to overestimate swim HRmax, and zones built on it will feel too easy. Two fixes:
Subtract about 10 bpm from the estimated HRmax for swim zones (the calculator below has this option), or
Better, use a measured swim HRmax from a swim test.
Other swim-specific points: HR also varies by stroke (breaststroke and fly often differ from freestyle), water temperature, and whether the swimmer is tapering or training heavy.
06
Zone calculator
07
Pulse-count practice
Find your pulse (wrist or neck) and rest your fingers on it. Choose a count time and press Start. You will hear a beep when the count starts and a longer beep when it stops. Count the beats in your head, then type the number in and press Check.
Fingers on your pulse, then press Start.
10.0
Tip: do two counts a minute apart. If they differ by more than 4–6 bpm at rest, check your technique. If you filled in the zone calculator above, the result is placed in your zone.
08
Limits & good habits
HR lags behind effort — it takes 30–60 seconds to settle at a new pace, so it is poor for very short repeats.
It is affected by heat, hydration, caffeine, stress, poor sleep, illness and medication. Compare like with like.
Track trends (the same test every few weeks), not single readings.
A resting HR more than about 5–7 bpm above a swimmer's normal for several days is a prompt to check on sleep, load and health — not a diagnosis.
Dizziness, chest pain, or an unusually high or irregular pulse at rest are reasons to stop and seek medical advice.
This guide is general education for coaches and swimmers, not medical advice. Swimmers with a heart condition or on medication should follow advice from their doctor.