Now measure it right.
Knowing your Zone 2 range is step one. Staying in it while you train is step two. And that depends entirely on how you measure heart rate.
Wrist-based optical sensors (Apple Watch, Garmin Fenix, Whoop) can lag 30 seconds or more in steady-state aerobic work. That's enough to drift into Zone 3 without realizing it.
A chest strap reads every beat in real time, with ECG-level accuracy. It's what Zone 2 training was designed around.
Do you train with a chest strap?
A few things to check.
- Wet the electrodes before each session. Dry skin causes signal dropouts.
- Wear it snug, just below the pectoral muscles. It should not bounce.
- In Garmin and Apple Watch: set HR source to the external strap before starting your activity.
- Give it 2 minutes to stabilize before trusting the reading.
Garmin HRM-Pro Plus
Stores data on the strap itself. Great for the gym or when you leave your watch behind.
Polar H10
Beat-by-beat ECG accuracy. Bluetooth and ANT+. Battery lasts a year.
Wahoo TICKR
Accurate, simple, pairs with virtually any app or device. The easiest entry point.
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