Polar Verity Sense

Why an optical sensor beat expectations

The interesting thing about the Verity Sense is that it uses the same fundamental technology as the wrist sensor you are probably unhappy with — light through skin, looking for the pulse — and it produces dramatically better numbers. The variable is not the technology. It is where the sensor sits.

The 2025 study isolated this deliberately by running three identical Whoop 4.0 units simultaneously at the wrist, the forearm and the upper arm on the same 28 participants, against a Polar H10 reference. Same hardware, same firmware, same person, same session — only the position changed. The proximal placements won at every intensity tested.

The forearm is less mobile than the wrist, better perfused, and lets a band hold a sensor flat against skin without a joint moving underneath it. That is the entire mechanism, and it is why the Verity Sense is a legitimately different proposition from a watch rather than a marginally better one.

The measured results, exactly as published

• At rest: approximately 1.6 ± 0.8% MAPE — the lowest of any device in the study.
• Graded treadmill (modified Bruce protocol): bias under 0.1 bpm, concordance correlation 0.997.
• Burpees: below 0.50 concordance — along with every other optical device tested.

We publish the third bullet with the same weight as the first two. A page that quotes 0.997 and omits the burpee result is selling, and the burpee result is the one that tells you whether this device suits your training.

What it does beyond heart rate

Polar publishes dual Bluetooth connections plus ANT+, on-board recording so it can capture a session with no phone or watch present, and a swim mode with a goggle-strap mount. That recording capability is genuinely useful: it makes the Verity Sense the only device in our heart-rate roster that can produce a heart-rate file from a session where you carried nothing else.

It is rechargeable rather than coin-cell, which is the practical trade against the H10. Convenience against 400 stated hours you never think about.

Verity Sense or a chest strap?

Our ranking puts the H10 first and the Verity Sense second, and the gap is smaller than that ordering suggests. The H10 wins on evidence because researchers use it as the criterion — the strongest evidentiary position a sensor can occupy — and on the strength of electrical measurement as a physical principle.

But the honest guidance is behavioural. If a chest strap means you will not wear a sensor, the armband with the 0.997 concordance is the better instrument for you, because it will exist in your data and the strap will not. The only training where we would insist on the strap is explosive, stop-start work, where the published result is unambiguous that nothing optical copes.

What we could not verify

• Performance outside the tested protocols. The study covered rest, a cycling warm-up, burpees and a graded treadmill test. Cold-weather running, swimming and long steady rides were not tested.
• Long-term consistency. A single-session study says nothing about how the device behaves after a year of sweat and washing.
• The swim mode. Polar publishes it; nobody has measured underwater performance that we could find.
• Stated battery.Polar's figures under Polar's assumptions. We have not run one down.

Who should not buy it

Anyone whose training is mostly explosive and stop-start — CrossFit, circuits, hard intervals with full recoveries. In the burpee protocol every optical device tested fell below 0.50 concordance, this one included, and buying the best optical sensor does not escape a limitation that is optical rather than brand-specific. Buy the H10 for that.