Ran three different biological age calculators last winter. Epigenetic clock estimate, one based on blood panels, one that used grip strength and a VO2 proxy. Got three different answers spread across about 9 years. That’s not a measurement. That’s a shrug. What actually tracks for me: CRP trending down over 6 weeks correlates to sleeping better and knee pain dropping. Resting HR sustained below 58 bpm correlates to not needing three days to recover from a leg session. Those aren’t longevity metrics. They’re function metrics. Same thing. The Fedichev framing - aging as accumulated stochastic damage rather than a program running out - implies the real target is inflammatory load and repair capacity, not the clock readout. If the model is right, chasing the number on a bio-age test is the wrong lever. What you want to move is the underlying damage rate. Track what moves. Not what calculates. ymmv