"Peakspan" should be the longevity marker everyone's talking about.
It refers to how long we can maintain 90% or more of our peak capacity in one of several health domains like muscle strength, cognitive function, or fertility.
And it recognizes that these systems peak at different ages and decline at different rates. So we need to strategically target each one as we age to maintain their function as high (and for as long) as possible.
I spoke with @StevenBartlett about "Peakspan" recently on his podcast.