Amazfit has launched the Helio Strap Pro at the HYROX World Championship in Stockholm. It is a new two-piece system built to measure not just cardio effort, but muscular load too, which is the part most wrist-based wearables usually miss.

That matters because HYROX is not just a running event with a few unpleasant breaks in the middle. It is a race where sled pushes, SkiErg work, wall balls and other stations put serious strain on the body in ways a normal wrist sensor often cannot properly measure.

What the Helio Strap Pro is

The Helio Strap Pro combines two devices. The first is the Helio Core Motion HR, an updated arm or wrist-worn optical heart rate sensor. The second is the new Helio Core Motion, a waist-mounted 9-axis motion sensor worn at the centre of the body.

The arm sensor handles the usual health and workout tracking jobs. It supports more than 50 workout modes, tracks heart rate, SpO2, sleep, stress and HRV, and feeds a refined version of Amazfit’s HybridCharge readiness score.

The waist sensor is the more specialised part. It has no display, no heart rate sensor and, at launch, no standalone use outside HYROX Race and HYROX Simulation modes.

Why Amazfit built it

Cardio load is relatively easy for modern wearables to estimate. Time spent in heart rate zones can be turned into a decent enough training stress score for running, cycling or rowing.

Muscular load is trickier. To estimate that properly, a system needs to understand movement patterns, speed, acceleration and the physical work being done. A single wrist sensor is not especially useful when the key movement is happening through the legs, torso or whole body.

That is where Amazfit thinks this setup has an edge. In HYROX, station weights are fixed by the event format, which removes one of the hardest variables to estimate. That makes it easier for the system to turn movement data into a more useful muscular load score.

How it works

The waist sensor sits at the centre of mass and works with the arm or wrist sensor to create a two-point movement signature. Amazfit then compares those signatures against a trained library of 30 HYROX and strength exercises.

The idea is simple enough on paper: identify the movement, judge whether it is a whole-body or more isolated effort, then use speed and acceleration data to estimate mechanical work. Compared with the original Helio Strap, the second sensor is there to improve classification and measurement accuracy.

There is one catch. The waist sensor has to be calibrated before every HYROX session, because position and orientation affect how accurate the readings are.

What the app shows

After a HYROX Race or HYROX Simulation, the Zepp app delivers three main outputs: a cardio and muscle exertion split, per-station movement evaluation, and natural-language feedback across the race.

In Amazfit’s launch example, a sample session showed 32 cardio, 27 muscle and 54 total, presented as a 60/40 split. The app also breaks down all 16 stages of a HYROX event, covering both the eight runs and the eight workout stations.

That extra waist data is especially useful for things like sled push analysis. A wrist sensor might show effort, but it cannot properly detect centre-of-gravity shifts or lateral sway under load. The waist sensor can, which is the whole point of the added hardware.

Battery life and compatibility

The Helio Core Motion HR is rated for up to 11 days of battery life on a single charge. The waist sensor is rated for up to 40 days, which makes sense given that it is only active during HYROX-specific sessions.

At launch, the full Helio Strap Pro system works only with the Amazfit Balance 3 and Balance Ultra. Support for other watches has not been announced.

The current limits

This is very clearly a HYROX-first product at launch. The waist sensor only works in HYROX Race and HYROX Simulation modes, and broader workout support is only promised for a future update with no timeline attached.

Amazfit is also still working on a few parts of the wider platform. Venue geometry data is in development, which matters because HYROX run segments and transitions are not always laid out exactly the same at every race. Race prediction is another unfinished area, with personalisation based on an athlete’s own race history acknowledged as a gap.

Pricing has not been announced yet either, so the final value argument will have to wait.

FAQs

Does the Helio Core Motion waist sensor work outside HYROX modes?

No, not at launch. It only works in HYROX Race and HYROX Simulation modes for now.

Which watches support the full Helio Strap Pro system?

At launch, the full setup is limited to the Amazfit Balance 3 and Balance Ultra.

Do you need to calibrate the waist sensor every time?

Yes. Amazfit says calibration is required before every HYROX session.

Is it useful for normal gym training?

The arm sensor is. It supports more than 50 workout modes and full health tracking on its own. The waist sensor and its muscular load analysis are currently HYROX-only.

Has Amazfit announced the price yet?

No. Pricing had not been announced at the time of writing.