Best heart-rate monitors for HIIT and strength

Wrist sensors lose the plot in the gym. In a hard session your heart rate jumps fast while your wrist flexes around a bar, and that's the worst case for a sensor reading blood flow with light.

A chest strap reads your heart's electrical signal directly. So that's the case for one, and it's a simple one. I haven't worn any of these monitors, and the product facts below come from maker and retailer pages, checked on 3 November 2026.

A heart-rate monitor isn't a medical device. Readings are estimates for general fitness and wellness. If you have a heart condition, follow your care team's guidance on training zones and not a watch reading. Etiwy 2019, peer-reviewed, found optical monitors less accurate than an electrode chest strap in 80 cardiac rehab patients.

What the wrist gets wrong

Zhang 2020 is the wide view: a peer-reviewed meta-analysis of 44 articles and 15 brands. Wrist readings averaged 0.51 bpm low on a treadmill (95% CI -1.60 to 0.58) and 7.26 bpm low in resistance training (-10.46 to -4.07), and averages hide larger individual errors. That gap grew by 3 bpm for every 10 bpm rise in heart rate. So the higher your heart rate climbs, the further off the wrist gets.

Lee 2026, peer-reviewed and funded by SOLUM Health Care, which employs one author, is more recent. It tested the Apple Watch Series 7, Galaxy Watch 4, Fitbit Charge 5 and Garmin Vivosmart 5 on 62 healthy men against ECG. Only the Apple Watch showed no significant difference in resistance exercise, and limits of agreement ran to about 10 bpm either way. On a 150 bpm effort, that can put you across a training-zone boundary.

Intervals look similar. Reddy 2018, peer-reviewed, tested 20 healthy adults, and the worst errors came in high-intensity bike intervals: -11.4% (SD 35.7) on the Fitbit Charge 2 and -14.3% (SD 20.5) on the Garmin vivosmart HR+. Both models are obsolete. I found no large independent study of current flagship watches in structured hard intervals, and I won't guess. Why wrist heart rate fails goes through the reasons.

What's proven about the straps

Less than you'd think.

Gilgen-Ammann 2019, peer-reviewed and read as an abstract only, had 10 healthy adults do five activities from low to high intensity. A Polar H10 detected 99.6% of RR intervals correctly overall and 99.4% at high intensity, while a Holter ECG monitor fell to 89.8% at high intensity. The authors suggested a simple chest strap might be the gold standard for RR intervals when intense activity with strong body movement is studied.

Ten people is a small sample. I haven't confirmed its funding, and it wasn't a barbell session. Still, it's why researchers keep using the H10 as a reference, as Schweizer 2025 did. The H10 review covers where it falls short.

That result is the H10's alone. The H9 is also an electrical chest strap, but I read no separate test of it. The Wahoo TRACKR has only a reviewer's check: Tom's Guide (independent, non-peer-reviewed) wore it beside an H10 on runs, rides and a strength session, and calls its accuracy spot on, with no figures. Buying either is a fair bet on how chest straps work, and it's still a bet.

Armbands: a middle option

In Schweizer 2025, peer-reviewed, a Polar Verity Sense on the upper arm came within 1.43 bpm of an H10, on 16 adults across nine activities from lying down to HIIT. A Polar Vantage V2 on the wrist was 6.41 bpm out.

Every device was Polar's, and data were processed to remove outliers. The authors declare no conflicts, and I saw no funding statement. Keep that in mind.

Tattoos may matter too. Navalta 2025, peer-reviewed, found the Verity Sense less accurate on tattooed skin, at 22.9% error at rest against under 5% on clear skin. The sensor dropped out for 9 of 25 people at rest, though, and removing those readings closed the gap. It's one small study.

The Wahoo TICKR FIT wasn't in any of these studies.

How they compare on the practical stuff

All five speak both ANT+ and Bluetooth, so pairing rarely decides this. How to connect a chest strap has the steps.

Garmin users will notice the gap. The HRM 600 and HRM 200 publish battery in months at an hour a day, so they won't sit on this bar in hours. Polar H10 vs HRM 600 vs Wahoo TRACKR gives them a proper hearing.

What I'd buy

For HIIT, I'd get the H10. It has the only peer-reviewed strap result in hard efforts here, and I'd pay for evidence over a nicer charging port.

For strength, ask whether you need beat-by-beat data at all. Between sets you mostly want to see recovery, and the H9 will show that. If a strap is what stops you wearing a monitor, take the Verity Sense and accept the thinner evidence. See the gym and bike goal page for more.