Free Flow · Wearables Meet Their Reference · Saturday The Week in One Number 0.98. That's the concordance correlation coefficient (CCC) for Oura Gen 4's nocturnal resting heart rate against an ECG reference — mean absolute percentage error just 1.94%. Dial and colleagues (Physiological Reports, August 2025)
The Flow · Trusting Your Overnight HRV Number · 2026-07-26 This week's Deep Read: what a five-device validation study says about whether your wearable's HRV number is worth acting on. Opening Flow A validation study puts a hard number on a soft assumption. Dial and colleagues compared five
Metrics are signals, not verdicts Consumer wearables now report recovery scores, HRV, sleep stages, and strain numbers daily. Used well, these are useful trend signals. Used badly, they are a daily source of anxiety and bad training decisions. The difference is knowing what each metric actually measures, and what it
Two words, two qualities Mobility and flexibility are used interchangeably in fitness marketing. They are not the same quality, they are trained differently, and confusing them leads people to train the wrong one. Flexibility: passive range Flexibility is the range a joint can be moved through by an external force
The short version A daily mobility flow is a short, sequenced set of movements that takes joints through controlled ranges of motion. Ten to fifteen minutes, most days, beats an occasional long session for most desk-bound adults — not because of any single magic movement, but because range of motion is
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