Every morning, millions of people wake to a number that claims to know whether they should train hard. Heart rate variability has become the default readiness signal in consumer wearables, and it has real evidence behind it. Almost all of that evidence, though, comes from runners and cyclists, and the picture changes once a barbell is involved. For a lifter, the question is specific. Does a morning HRV reading say anything about whether the quads are ready for heavy squats,