Screenless fitness bands have one awkward problem: the wrist is a terrible place to measure heart rate during a hard workout. Polar just admitted as much in the most practical way possible. It launched a Sport Armband for its Loop tracker that moves the optical sensor from your wrist to your upper arm, and it costs $29.90.
It is a small accessory, but it targets the single biggest complaint people had about the Loop. If you lift, do intervals or run hard, the new strap could be the difference between a heart rate graph you trust and one you ignore. Here is what Polar is selling, what the early evidence says, and where the limits are.
Quick take
The Polar Loop Sport Armband is an elastic textile strap that holds the Loop’s sensor module on your bicep instead of your wrist. It is priced at $29.90 (about £25.50 in the UK) and comes in two sizes. It is built for training sessions, not for wearing all day, so the wrist band stays your 24/7 option.
What Polar Actually Launched
The Loop is Polar’s answer to the Whoop style of tracker: no screen, no required subscription, and a lightweight band meant to be worn around the clock. That design is great for sleep and recovery tracking. It is less great when your wrist is flexing under a barbell or snapping through burpees, because optical sensors lose contact with the skin and start guessing.
The Sport Armband fixes the placement rather than the sensor. You pop the Loop’s module out of the wristband, slide it into the new elastic strap and wear it on your upper arm. The idea is the same one behind Polar’s older Verity Sense, which has long been a favorite of runners and lifters who want chest strap quality without the chest strap.
| Detail | Polar Loop Sport Armband |
|---|---|
| Price | $29.90 in the US, £25.50 in the UK, €29.90 in Europe |
| Material | Elastic textile strap |
| Sizes | S-M (listed for roughly 24 to 40 cm arms) and L-XL (roughly 31 to 56 cm) |
| Sensor position | Upper arm (bicep) |
| Intended use | Training sessions, not 24/7 wear |
| Works with | Polar Loop only |
Based on Polar’s product page and launch coverage from Wareable. Regional pricing and size ranges can change, so check Polar’s store before you order.
Why the Wrist Struggles During Hard Workouts
Optical heart rate sensors shine green light into your skin and read the tiny changes in reflection as blood pulses through it. That works well when your arm is still, which is why wrist trackers are so good at resting heart rate and sleep. It gets messy when your forearm muscles tense, your wrist bends and the strap slides a few millimeters on every rep.
The bicep is calmer. There is more soft tissue, less bone movement and a strap that can sit snugly without cutting off your range of motion. That is the same reason armband sensors have such a loyal following among serious trainers.
What the Testing Says So Far
Polar has not published a lab study for the new armband, and independent testing of this exact strap is still thin. What we do have is a pile of related evidence pointing the same way:
- A 2025 review of the original Loop found it was more accurate on the bicep than on the wrist, though still short of Polar’s older OH1 and Verity Sense sensors.
- In a running interval test of Garmin’s Cirqa band, the wrist reading ran about 9 to 10 bpm low at the start of four of five reps, while the bicep placement stayed within 0.3 bpm of a Whoop MG, a Polar armband and a Garmin HRM 600.
- A separate TechRadar HIIT test of the Cirqa put it at 153 bpm against 155 bpm for a Polar H10 chest strap, which is inside the normal margin of error.
Note that the last two tests used a different brand’s band, so they show what the placement change can do, not what Polar’s strap will deliver. Still, the pattern is consistent: the wrist is where screenless bands lose accuracy, and the upper arm is where they get it back.
Sport Armband vs Verity Sense: Do You Need Both?
This is the question most buyers will ask. Polar already sells the Verity Sense, a standalone optical sensor that straps to your arm and broadcasts live heart rate. It lists at $104.95 in the US, with its own armband sold separately at $24.99.
The two are not the same thing. The Verity Sense is built to talk to other devices, such as a bike computer, a gym machine or another watch, over Bluetooth and ANT+. The Loop, by contrast, is designed around syncing with the Polar Flow app, and retailer comparisons note that it does not broadcast live heart rate to outside gear. If you want to pair a sensor with a third-party screen, the Verity Sense is still the better tool. If you already own a Loop and simply want better numbers recorded in Flow, the $29.90 armband is the cheaper fix.
| Loop + Sport Armband | Verity Sense | |
|---|---|---|
| Extra cost | $29.90 on top of a Loop | $104.95 standalone |
| All-day sleep tracking | Yes, with the wrist band | No |
| Broadcast to other devices | Not designed for it | Yes |
| Best for | Loop owners who train hard | Athletes who pair with watches and gear |
The Limits You Should Know About
A $29.90 strap cannot rewrite what the Loop is, and Polar is upfront about that. A few things to keep in mind before you buy:
- It is for workouts only. Polar positions the armband for training sessions. For sleep, recovery and all-day tracking you go back to the wrist band.
- Swapping takes effort. Moving the module between strap types is fine for a gym session, but it is a step you have to remember every time.
- It still will not match a chest strap. The earlier Loop review found the bicep reading good but behind the Verity Sense, and a chest strap remains the gold standard for pure accuracy.
- There is still no screen. You will not see your heart rate on your arm mid-set, so you need a phone, watch or gym display to watch it live, and the Loop’s broadcast options are limited.
Worth buying if you
- ✓ Already own a Polar Loop
- ✓ Lift weights or do HIIT
- ✓ Care about accurate zones in Flow
Skip it if you
- ✕ Mostly walk or do easy cardio
- ✕ Need live heart rate on other gear
- ~ Already wear a chest strap
How It Fits the Screenless Tracker Race
Polar is not alone in noticing the wrist problem. Garmin’s new screenless band lets you move the sensor to the bicep too, and our Garmin Cirqa review roundup covers how it compares with Whoop and Fitbit’s Air. One difference stands out: Notebookcheck reports that the Cirqa locks its current heart rate view behind a $6.99 monthly subscription, while the Loop shows heart rate without one.
That is the Loop’s real selling point. If you are shopping for a tracker that will not charge you rent, our list of the best smartwatches with no subscription is a good place to compare options. And if you are a Polar fan with a traditional watch as well, the brand has also been busy on the software side, as we covered in the Polar 6.0.18 update.
Frequently Asked Questions
How much does the Polar Loop Sport Armband cost?
$29.90 in the US, £25.50 in the UK and €29.90 in Europe, according to Polar’s listings and launch coverage.
Does the Sport Armband work with other Polar devices?
No. Polar lists it as an accessory for the Polar Loop only. The Verity Sense has its own separate armband.
Can I wear it all day?
Polar designed it for training sessions. For continuous 24/7 tracking, including sleep, you should use the standard Loop wristband.
Is the bicep really more accurate than the wrist?
In the evidence we have, yes. An earlier Loop review and a separate Garmin Cirqa test both found upper arm readings tracked reference sensors more closely during hard efforts. Polar’s own armband still needs more independent testing.
What sizes are available?
Two: S-M and L-XL. Polar’s listing gives ranges of roughly 24 to 40 cm and 31 to 56 cm for arm circumference, so measure before you order.
Final Verdict
The Bottom Line
For Loop owners who train hard, the $29.90 Sport Armband is the cheapest upgrade Polar could have shipped and it goes straight at the tracker’s biggest weakness. It will not turn the Loop into a chest strap or a smartwatch, and you should wait for independent numbers before treating it as proven. But as a low risk fix for shaky workout heart rate, it looks like an easy yes.
Featured image: Pexels.
About this article: GeekBlog covers U.S. technology news, AI, phones, smartwatches and gaming. Every story is written and checked under our Editorial Policy. Spotted a mistake or have a story tip? Contact our editors.
