Anyone who has worn a wrist tracker through a set of heavy deadlifts has probably seen their heart rate do something strange. It jumps, freezes, or reports a near-sprint effort while you are standing still between reps. Most of the time that is not your heart at all; it is your grip. Tendons shift, blood flow in the wrist changes, and the optical sensor loses the plot. Polar's answer, launched on 7 October 2026, is a $29.90 textile armband that moves the screenless Polar Loop up to your upper arm for workouts, where optical heart rate is far more reliable. Here is what it is, when it helps, how to wear it, and whether it is worth adding to a Loop you already own.
Disclosure: Fitcoin is our product. We are not affiliated with Whoop, Oura, Google, Fitbit, Garmin, Polar, Amazfit, Xiaomi, Samsung, Suunto, Apple, Huawei, Hume Health or any other brand named on this page. We do not sell trackers and we take no affiliate commission. Where Fitcoin appears, it is as the rewards and insights app that reads the data these devices and workouts write to Apple Health or Health Connect. Everything below is a wellness estimate for general fitness, not medical advice.
What Polar has launched
The announcement came from Polar's headquarters in Kempele, Finland, on 7 October. The Polar Loop Sport Armband is a soft, elastic sleeve designed for the upper arm, sold as an accessory for the screenless Polar Loop. Polar's US store lists it at $29.90 and is unusually clear that it is intended for training sessions rather than all-day or overnight wear. Sleep and everyday tracking are meant to stay on the wrist strap. The same day, Polar also released a reversible magnetic silicone wrist band and a vegetable-tanned leather band, both sold separately. Those two are about style; the armband is the only one that actually changes how the Loop measures.
There is no new sensor involved. The Loop's optical module simply pops out of the wrist strap and into the armband cradle. What changes is the location, and that matters more than you might expect. Polar has been making the case for upper-arm optical heart rate for years with its Verity Sense sensor: there are fewer tendons in the way, far less interference from gripping, and a surface that does not bounce around during a kettlebell swing or a padel smash. A 2025 validation study comparing the Verity Sense to ECG found the upper-arm sensor tracking the reference closely across a mix of resting and harder efforts, while a Polar wrist watch in the same study was good but noticeably more variable depending on the activity. That study was of a different Polar sensor, not the Loop, but it illustrates exactly why this accessory exists.
The Loop itself is unchanged at $199.99, or £149.90, with no subscription required. The armband does not alter that, and it does not do anything about Polar Flow, the app, which remains the weakest part of the Loop package in our review. What you are buying is a better place to wear a device you already like.
When the wrist struggles, and when it does not
Wrist-based optical heart rate is perfectly fine for a lot of exercise. Steady indoor cycling is kind to it, because your hands rest on the bars and the band stays still. Easy running is usually fine too. The trouble begins when your wrists are doing work: holding a barbell, swinging a racket, gripping a rowing handle, climbing a rope, or dropping into burpees. Gripping changes the blood volume under the sensor, and the algorithm either freezes, spikes, or smooths the spike into a calorie figure you did not actually earn.
Polar specifically names weightlifting, tennis, padel and HIIT as the use cases for the armband, and that matches the physics well. It is less useful for sports where you need something on your wrist anyway, where a sleeve under a jacket would be annoying, or where you are in the water. It is also not a replacement for a chest strap if you need precise, beat-by-beat intervals for structured training. An upper-arm optical sensor is a significant step up from the wrist, but a chest strap is still the gold standard, and for a session you are pacing strictly off heart rate, that is the tool to use.
Whoop owners have been sliding their sensor up to the bicep for years, and Amazfit's Helio Strap was designed as an arm band from the start, so Polar is arriving a little late to this idea. The upside of lateness is that the Loop gets the cleanest version of it: two straps and one pod, so the device you sleep in does not have to be the one you lift in, and charging stays simple. The one thing to watch is forgetting to swap it back afterwards. Polar says the armband is not designed for overnight wear, and your sleep data will be the first thing to suffer if you leave the pod in the sleeve.
How to wear it properly
Position the sleeve high on your upper arm, snug enough that one fingertip slides underneath but a second does not, ideally on the arm that is not carrying a bag strap. The sensor window should sit over muscle rather than on the bony outside edge of the arm. Start your session in Polar Flow before you pick up the bar, and give it twenty seconds or so of easy movement so the sensor locks on while your blood flow is steady, then get into the workout. If the heart-rate trace still looks jumpy, tighten the sleeve a notch before blaming the sensor; a loose fit is the most common cause of poor optical readings.
Take it off and move the pod back to the wrist when you finish. The wrist strap is the one Polar has tested for all-day wear, and it is where the Loop's roughly eight-day battery life and sleep tracking have been validated. The armband's job is an hour at a time. It is comfortable enough that you may be tempted to leave it on, but doing so means losing the sleep and recovery data that is the main reason to own a Loop, and the textile sleeve is not what Polar had in mind when it rated the device for the shower.
If you do not already own a Loop, the armband is not a reason to buy one by itself. It is, however, a good reason to buy one if you had been considering a screenless, no-subscription recovery band and the poor gym heart-rate accuracy of wrist sensors was the objection pushing you towards a Whoop. The armband removes that objection for $29.90. It does not fix Polar Flow's dated interface, and it does not add blood oxygen or skin temperature sensing that the Loop never had. For the full buy-or-skip decision, our Loop review, the Loop vs Fitbit Air comparison and the Whoop vs Polar Loop head-to-head are the places to go. The armband is a small, specific improvement on top of a band that was already good value, and if you lift, it is an easy yes.
Sources: Polar's 7 October 2026 press release, the US Polar Loop Sport Armband product page and Polar's current Loop pricing, all checked 2 November 2026. The 2025 Verity Sense validation study is cited for the upper-arm placement principle and was not a test of the Loop. We have not yet lab-tested the armband ourselves.
The band underneath the sleeve: Polar Loop review, Whoop vs Polar Loop, best Whoop alternatives.
Frequently asked questions
What is the Polar Loop armband?
The Polar Loop Sport Armband is a $29.90 elastic textile sleeve, launched on 7 October 2026, that holds the Polar Loop's sensor pod on your upper arm during workouts. Upper-arm placement gives more accurate optical heart rate during lifting, racket sports and HIIT than the wrist does.
Can you wear the Polar Loop on your bicep all day?
Polar does not recommend it. The armband is designed for training sessions only, and sleep and all-day tracking should be done with the pod back in the wrist strap, which is what Polar has tested for 24/7 wear.
Does the armband make the Loop as accurate as a chest strap?
Not quite, but it gets much closer than a wrist strap does. A 2025 study of Polar's Verity Sense upper-arm sensor found it tracking ECG closely across varied efforts. For precise interval training, a chest strap is still the most accurate option.
Do I need a new Polar Loop to use it?
No. The armband is an accessory that works with the existing Polar Loop. You simply move the sensor pod from the wrist strap into the armband for your workout and back again afterwards.
About the author: Harris Khan is the co-founder and CTO of Fitcoin, a UK fitness-rewards and health-insights app that reads Apple Health and Health Connect.