The Aging Biomarkers That Actually Predict Outcomes

Chronological age is a strange metric to optimize for, because two people who are the same age can have wildly different biological function, and it's the biological function — not the birth year — that actually predicts health outcomes. What's changed recently is that a small number of easily measured markers turn out to predict long-term health and mortality risk about as well as vastly more complex and expensive testing.

Cardiorespiratory fitness, commonly measured as VO2 max, and grip strength are two of the most studied examples: both are simple to test, both correlate strongly with all-cause mortality risk across large population studies, and both are, unlike genetics, something an individual can meaningfully change through training.

This reframes healthy aging as a much more actionable problem than it's often presented as. Instead of an opaque, expensive diagnostic search for what might go wrong eventually, it becomes a short list of trainable metrics with a clear, well-evidenced path to improving them.