New Delhi, June 7 -- When most fitness watches calculate how ready you are to train, they read your heart rate variability overnight and call it done. Amazfit's new Balance 3 takes a different approach. Arrived at the gym after a red-eye flight and two drinks at the airport? Log it. The watch adjusts. That is the premise behind HybridCharge, the readiness system sitting at the center of Zepp Health's most significant product launch in years.

The Amazfit Balance 3 and Balance Ultra went on sale June 2, starting at $369.99 and $599.99 respectively. They are the first devices to run Zepp OS 6, a platform update that Zepp Health has confirmed will eventually reach ten more of its existing smartwatches. The Balance 3 Titanium, a $449.99 versi...