Wearables · Explainer · 5 min ·
Your watch says 148, but is that really your heart rate? A wrist watch reads blood flow with green light; a chest strap reads the heart's own electrical signal. For steady jogging they agree well, but when effort changes fast or your wrist is gripping a bar, the wrist can lag and drift.
Slide the watch loose, switch workouts and see the gap, then learn when a strap is worth buying and what to look for.
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The simplest way into chest-strap accuracy: the same kind of ECG sensing as the pricier Polar, with a washable soft strap. It connects to one Bluetooth device at a time and has no built-in memory, which is fine if you train with a single watch or phone app.
Chest strap (ECG) · Bluetooth + ANT+ · Coin cell, ~400 h
Adds a grippier strap, two simultaneous Bluetooth connections and memory for phone-free sessions. A good fit if you mix a watch, a bike computer and a training app.
Chest strap (ECG) · Bluetooth + ANT+ · Stores one workout
Rechargeable instead of a coin cell, with running metrics such as cadence if your Garmin watch can show them. Worth it mainly for runners already in the Garmin ecosystem.
Rechargeable · Bluetooth + ANT+ · Running metrics