Topic
Blood Flow Restriction Training: What the Evidence Actually Supports
Occlusion cuffs promise big gains from light loads. The research is real but narrower than the marketing suggests.
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How Wearables Measure Heart Rate Variability
Watches and rings derive heart rate variability from the pulse wave using photoplethysmography, while chest straps read the heart's electrical signal. Studies show the methods agree at rest, with error bars that widen under strain and noise.