#hrv
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Apple Watch Ultra 4 In-Depth Review: As Good As the Hype?
The payoff to last week's two hands-on videos: DC Rainmaker's full in-depth Ultra 4 review after swim/bike/run/row/track testing against a Polar H10 chest strap, published the day before the watch ships. Bottom line on the sensor: "this new heart rate sensor is very accurate thus far in my testing" — genuinely excellent plots even in the hard cases (outdoor road cycling vibration, rowing hand motion) — with the caveat that cold weather, where optical HR actually struggles, hasn't been tested yet (he lives somewhere hot; Apple's own study sites were California and Malaysia).
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Apple Watch Ultra 4 & Series 12: BETTER HR, Steps & ECG! (All You Need To Know)
Series 12 ($399, frame_0013) and Ultra 4 ($799) share a redesigned optical + electrical heart-rate sensor on the new S11 chip: repositioned photodiodes, larger power-efficient green LEDs, improved ECG electrodes (frame_0005, frame_0009, frame_0011).
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Apple Watch Ultra 4 Hands-On: 24 New Things Tech Deep-Dive
The Ultra 4 sibling to the same-day Series 12 hands-on, shot at Apple Park in the same session — and it carries the mechanism the Series 12 video left out: the LED array has been rearranged so the color diodes are now clustered by type (four green, four red, four infrared), which lets Apple drive 24/7 background readings off the green LEDs instead of the infrared ones. That's why background HR could go from every 5 minutes to every 5 seconds; it's an LED-grouping change, not just a faster sample loop.
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Apple Watch Series 12 Hands-on: What's Actually New?
DC Rainmaker's same-day hands-on from Apple Park: the Series 12 ($399, ships Sept 18) gets the S11 chip, a rebuilt optical HR package (24% larger rearranged ECG electrode area, eight windows with double photodiodes replacing four dots, a new LED array), a 60% stronger display, and new colors (dark bronze, gold, ceramic white/blue, Hermès) — "it's actually impressive how many more features there are than they showed in the keynote."
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Garmin CIRQA Ultimate Scientific Review!
Rob (The Quantified Scientist) systematically tested the Garmin CIRQA smart band against a Polar H10 ECG chest strap (exercise HR) and a ZMax EEG headband (sleep stages), worn both on the wrist and on the biceps — placement turns out to be the single biggest factor in this review.