Garmin HRM 600 review: why intervals need a chest strap
Here's the problem wrist watches don't advertise: during hard intervals, optical wrist heart-rate is often wrong exactly when it matters. The sensor reads blood flow through your skin, so it lags fast changes and can "cadence-lock" — latching onto your step rate instead of your pulse. For easy runs, fine. For HYROX-style intervals and station work, you can be pacing off a number that's 10–30 bpm off.
Why a chest strap fixes it
A chest strap reads your heart's electrical signal — the same principle as an ECG — instead of inferring it optically. That means it tracks rapid HR swings beat-to-beat with far less lag. For interval and threshold work — the backbone of a good HYROX build — that accuracy is the difference between training the right zone and guessing. It's the single highest-leverage accuracy upgrade most athletes can make.
What the HRM 600 adds
Garmin's HRM 600 (2025, ~$170) is the current flagship. Beyond accurate HR and HRV it captures full running dynamics (cadence, stride length, ground contact time, plus a new "step speed loss" metric for how much you brake each step), records activities standalone to Garmin Connect with no watch, broadcasts over ANT+ and Bluetooth, and runs ~2 months per charge. A genuine training-nerd favourite.
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Do you need it?
Easy-runs-only? Wrist HR is fine — save your money. Training intervals and threshold for a real HYROX result? A chest strap is worth it, and the HRM 600 is the do-everything option (any accurate chest strap helps if budget is tight).
Frequently asked questions
Is a chest strap more accurate than a watch for intervals?
Yes. Wrist optical sensors read blood flow through the skin and lag during fast efforts — they can even 'cadence-lock' onto your step rate instead of your pulse. A chest strap reads the heart's electrical signal (like an ECG) and tracks rapid changes far more accurately, which is exactly what interval and HYROX training demands.
Is the Garmin HRM 600 worth it?
If your training is interval- or threshold-heavy, yes — you get accurate real-time HR, HRV, and running dynamics. If you only do easy runs, wrist HR is usually good enough and cheaper.
Does the HRM 600 work without a watch?
Yes — it can record an activity standalone (HR, pace, distance, steps, calories) straight to Garmin Connect, and it broadcasts over ANT+ and Bluetooth to watches, bike computers and gym equipment.
Put the accurate data to work: Zone 2 guide · what actually predicts HYROX performance · all gear guides.
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