Personal tests in Toulouse (Garonne jogging, gym, HYROX type session), crossed with measurements from DC Rainmaker and the specialist press.

In brief

If you just want the answer:

• For whom? Regular athlete, crossfitter, runner, HYROX or bodybuilder who wants to seriously follow his recovery without a 24-hour watch or subscription.
• What Helio Strap does: Heart rate per second, HRV, detailed sleep, stress, energy score BioCharge™training load, VO₂ max, all connected to Zepp App and your Amazfit ecosystem.
• The hardware: 20 g, 22 mm nylon strap, BioTracker 6.0 optical sensor, 5 ATM, 232 mAh battery, up to 10 days of battery life.
• Price : around €99.90 at the official price, without any subscription behind.
• The big pluses: very solid cardio precision, serious sleep/recovery tracking, Amazfit Balance 2 / Helio Ring integration, Strava / TrainingPeaks / adidas Running / komoot compatibility, etc.
• The big ones –: no screen, auto detection of sessions still shaky, everything goes through the Zepp app, no integrated GPS, no medical functions.
• Quick verdict: if you're eyeing Whoop but the subscription is boring you, Helio Strap is today the most credible alternative at €100... provided you accept its pure screen-free side and its sometimes a little messy algorithms.

Brief. You want to know if you spend €100 here, or if you keep your cardio belt, your Whoop. Your watch. We decide, right?

See the Amazfit Helio Strap price and reviews on Amazon

1. Amazfit Helio Strap in two words: what you really buy

You are not buying an “extra bracelet”. You buy a cardio and recovery sensor that you can keep on 24/7 without blowing your wrist or your attention span.

A screen-free tracker designed for recovery

Officially, Helio Strap is:

• Only 20 g, reinforced polymer case, 5 ATM resistance, 22 mm nylon strap with hook-and-loop fastener, wrist 145–205 mm.
• Biometric sensor BioTracker™ 6.0 PPG (5 photodiodes and 2 LEDs), temperature sensor, accelerometer, gyroscope, Bluetooth 5.2.
• 232 mAh battery, autonomy announced up to 10 days in typical use, magnetic recharge in less than 2 hours.

No screen, no notifications, no widgets. Just a vibration for alarms. We are in the pure “I collect data, I return it to you in the app”.

If you are still hesitating between a real connected watch and a simple dedicated sensor, I have detailed the differences in a connected watch vs connected bracelet.

A link in the Amazfit ecosystem, not an isolated gadget

This point is key. Amazfit sells Helio Strap as a brick of a complete system: Balance 2 on the wrist, Helio Strap on the arm, Helio Ring on the finger, all centralized in Zepp App.

Concretely, Helio Strap can:

• Broadcast your heart rate in real time to your Amazfit watch, bike computer, treadmill or compatible fitness apps.
• Record your heart rate locally for up to 21 days, then push the data into Zepp App, even if your phone wasn't there.
• Power BioCharge, training load, PeakBeats status, VO₂ max, like a classic sports watch.

Basically: if you're already in the Amazfit ecosystem, it makes sense. If you're full Garmin, Polar or Suunto, there's no question.

See the Amazfit Helio Strap price and reviews on Amazon

2. Cardio accuracy, sleep, BioCharge: are the data reliable?

There, it's simple: either the data is good, or Helio Strap is useless.

2.1. Heart rate during exercise

This is the big strong point.

In its tests, DC Rainmaker shows that the Helio's cardio curve fits almost perfectly with a Garmin HRM belt on trails, bike rides and home trainers, including in sections that cause the optical sensors to suffer (rapid descents, variations in pace).

Same thing in the general press: several tests highlight a consistent, stable heart rate, even better than certain entry-level bracelets or watches.

What plays:

• Arm position with the Helio cuff: sensor closer to the heart, less disturbance due to wrist flexion, which clearly improves the stability of measurements on explosive WODs, burpees or rowing.
• The fact that Helio sends heart rate in real time to your watch or computer, like a classic belt, with no visible latency.

The use of 5 photodiodes in the BioTracker 6.0 (compared to 2 or 3 on the old generation), associated with the positioning on the arm, clearly reduces the motion artifact in the explosive phases of our tests, where the watches on the wrist still stalled.

On my personal sessions (tempo jogging around Toulouse, HYROX type session in the gym, split 30/30), the average and max frequency stick to more or less 2 to 3 bpm on my cardio belt. This is very correct for an optical sensor.

Frankly, there’s nothing to say about that: it’s solid.

This level of precision is not achieved with entry-level consumer bracelets. If you prefer to stick with a more mainstream and less expensive bracelet (with screen), I also dissected models like the Xiaomi Smart Band 10 in a complete field test of the Xiaomi Smart Band 10.

2.2. Sleep, HRV, Amazfit Helio Strap recovery: serious… with an optimistic bias

Helio Strap follows:

• sleep stages (light, deep, REM),
• sleep score,
• naps lasting more than 20 minutes,
• heart rate variability (HRV),
• the quality of breathing during sleep,
• a BioCharge score that tells you what energy state you wake up in.

In independent comparisons, the falling asleep and waking up times are very close to those of an Apple Watch Ultra, an Oura Ring or a Whoop, sometimes with a slight lag but generally within the nails.

Where Helio is a little “nice”:

• Sleep scores tend to be more generous than some competitors (Garmin or Oura), even when the night is objectively average.
• BioCharge can sometimes underestimate the impact of a tough session or overestimate a day where you suffered from nervous fatigue. It's progressing, but it's not yet at the level of the finesse of a Whoop on the charge and recovery part.

For a normal athlete, this is more than enough. For the athlete who wants to optimize peak form every week, it remains a brick among others, not an absolute oracle (and frankly, who believes 100% in a recovery algorithm?).

2.3. BioCharge and training load: useful, but not perfect

BioCharge is the Amazfit version of the Garmin Body Battery:

• you recharge at night based on actual sleep,
• you unload with your sessions, your day, your stress,
• you can go back a little with a nap or a really relaxing moment.

It works well to give you a tendency: “ok, I’m exhausted, it’s better to take your foot off the gas”.

But the algorithms still have two major flaws:

1. The day's load (Exertion) is capped at 100%, even if you exceed your quota, which means that two very different days can end with the same score.
2. The automatic detection of activities sometimes generates an avalanche of false sessions which pollutes the overall reading (Sunday with 7 to 10 sessions when you have done 2).

The good news: you can turn off auto-detection and only launch manual sessions from Zepp App. There, everything becomes much more coherent.

3. Helio Strap for everyday use: comfort, autonomy, ergonomics

If the thing irritates your wrist, you put it in a drawer. Simple.

3.1. 24/7 comfort: wrist or arm

The nylon strap is light, breathable, but like all fabrics it retains a little moisture after a shower or a very sweaty session. Nothing new.

Two clear uses:

• Wrist : ideal during the day, for the office, walking, short sessions. You almost forget the strap because it is so light.
• Arm (with dedicated cuff): clearly the best option for weight training, rowing, ski-erg, burpees, anything that strains the wrist. Helio stays in place, and the sensor better captures blood flow.

Point to know: the one size can be limited for very large wrists, you sometimes have to open the strap widely to put on the bracelet.

3.2. Real autonomy: promise kept in our field test

On paper: up to 10 days in typical use.

In practice, over a week of testing with:

• 4 cardio or strength training sessions of 45 to 60 minutes,
• 24/7 monitoring of heart rate, SpO₂ and stress,
• sleep tracked every night,

we are between 7 and 9 days before recharging, which is very close to the announcement. You can clearly go for a week on the road, in a van or on vacation without carrying the charger everywhere. (So, it depends if you carry around a lot of chargers, eh.)

Please note: no USB-C cable provided, only the small magnetic puck. Amazfit assumes that everyone already has cables at home. If you don't have one, you complain.

3.3. Zepp App, Strava and company: the integration that changes everything

Zepp App is the real dashboard:

• daily view with sleep, BioCharge, Exertion, HRV, stress, etc.,
• details of sessions with estimated VO₂ max, training load, aerobic and anaerobic effect, recovery time,
• Health profiles with PAI, multi-day heart rate and HRV trends and graphs.

On the external sync side, Zepp speaks natively with Strava, adidas Running, TrainingPeaks via Terra, komoot, Relive, Google Fit and Apple Health, and clearly specifies that Samsung Health and MyFitnessPal are not supported.

If you are looking for a product compatible with Strava without having to worry, you can take a look at my Strava compatible connected bracelet.

A recent update added a tennis mode and optimized the BioCharge and heart rate algorithms. The product is clearly alive on the software side.

4. Amazfit Helio Strap vs Whoop vs cardio belt: who should choose what?

The real question is there.

4.1. Face Whoop: subscription or one-shot payment

Whoop, it's the archetypal recovery sensor with monthly subscription. Helio Strap plays exactly on this terrain, but with around €99 once and for all.

The big differences:

• Subscription: Whoop makes you pay every month, Helio doesn't ask you anything after the purchase.
• Data and coaching: Whoop puts a huge focus on load, recovery score and coaching, Helio focuses on BioCharge, Exertion and classic stats (VO₂ max, training load, etc.) with an overall less coaching-oriented logic.
• Auto-detection reliability: Whoop auto-detects pretty cleanly, Helio still generates a lot of ghost activity if you leave the option enabled.
• Cardio precision and sleep: Cross-tests show that Helio holds its own against Whoop on heart rate and HRV, and that it is very good at sleep tracking for the price.

If you want a coach focused 100% on the load and recovery couple, with a closed ecosystem, Whoop stays one step ahead. But the price...

If you want 80-90% of the value without subscriptions and connected to a real GPS watch, Helio Strap makes more sense.

4.2. Faced with a cardio belt and a GPS watch

This is the most misunderstood comparison.

A cardio belt:

• is often more precise in pure cardio,
• does not track your sleep, your stress, your HRV, your overall recovery,
• only lives in sessions, not 24/7.

Helio Strap:

• serves as an optical cardio belt for your sessions,
• stays there night and day to nourish the recovery,
• powers your Amazfit ecosystem (Balance 2, Helio Ring, Zepp).

It doesn't completely replace a good polarized belt if you do very demanding workouts, but for 90% of people, it covers the cardio and recovery needs with a single product.

4.3. Faced with a simple Amazfit Balance 2 watch

You can live very well with a Balance 2 alone. That's enough to have heart rate, GNSS, VO₂ max, training load, sleep, stress and recovery.

Helio Strap becomes interesting in three cases:

1. You don't want to sleep with a big watch: you sleep with Helio, you only wear the Balance 2 during the day, the data remains consistent.
2. You do sports where the watch gets in the way: combat sports, tennis, crossfit, HYROX, team sports, manual labor. You put Helio on the arm with the cuff and you leave the watch in the bag.
3. You want to make cardio more reliable: Balance 2 on the wrist, Helio on the arm, the watch recovers the cardio signal from the Helio for all sessions.

5. Sensitive information to keep in mind

Two important reminders, because many people get it wrong:

• Helio Strap is not a medical device. Amazfit says it in black and white: neither the strap nor Zepp App is used to diagnose anything. It gives you signals, not prescriptions.
• It does not measure blood pressure, does not send an ECG, and does not replace a cardiologist or sleep test.

That's a bad idea, frankly.

If you have any doubts about your health, you go see a doctor. Point.

6. Shopping experience: where to find it, at what price, what to check

Today, Helio Strap is sold on the official Amazfit France store for around €99.90, and on major e-commerce platforms at a similar price, often with the mention “no subscription required”.

Some practical advice before clicking:

• Make sure you are taking the Helio Strap version (the bracelet), not just the armband and not the Helio Ring.
• Add the arm cuff if you do a lot of crossfit, HYROX or heavy weight training, it's clearly more comfortable.
• Make sure your phone is at least running Android 7.0 or iOS 15, otherwise Zepp will not install.

In terms of reliability, user reviews are around 4.2 out of 5 with several hundred evaluations, which is consistent with what I have seen in the field: a very good product, but not perfect.

7. Verdict: for whom the Amazfit Helio Strap is a real good choice

We cut it short.

Helio Strap is for you if:

• you want real recovery monitoring (sleep, HRV, BioCharge) without a 24-hour watch,
• you do HYROX, crossfit, weight training, sports where the watch gets in the way and you want a reliable arm sensor,
• you are already in the Amazfit ecosystem (Balance 2, Helio Ring) and you want to densify data without changing brands,
• you refuse on principle to pay a monthly subscription like Whoop but you still want serious follow-up.

Helio Strap is not for you if:

• you absolutely want a screen on your wrist with notifications, widgets, music,
• you want ultra-sophisticated recovery algorithms with daily coaching like Whoop plus human coach,
• you are already locked into a competing ecosystem (Garmin plus HRM belt, Polar, etc.) and you have no intention of switching to Zepp.

Clear summary

• Price : around €100, one-time payment, no subscription.
• Comfort : excellent, especially in the arm version, 20 g, we quickly forget it.
• Cardio precision: very good for an optic, at the level of more expensive solutions according to independent tests.
• Sleep and recovery: complete, sometimes a little optimistic, but more than sufficient to control its load.
• Algorithms: Useful Bioload, Exercise could be improved, auto-detection of sessions still messy.
• Ecosystem: huge interest if you already have a Balance 2 or plan to upgrade to one.
• Boundaries : no screen, no GPS, no ECG or medical functions, compatibility limited to certain third-party apps.

Frankly ? You want a “Whoop without subscription” that speaks to your Amazfit watch and Strava. The budget is contained. It ticks the boxes, even with its still rough algorithms. That's the alternative, period.

Author : David Deteve – Independent writer & field tester

Cross-tests in October–November 2025 – Toulouse and surrounding areas (jogging, weight training, simulated HYROX session).