Can confirm....
https://www.theguardian.com/science/article/2024/aug/14/scientists-find-humans-age-dramatically-in-two-bursts-at-44-then-60-aging-not-slow-and-steady
Can confirm burst 1
That would explain why at 59 when I would tell people my age they kept saying, "Wow, you don't look it!" and at 61 they just say, "Yup."
Bringing it back and adding some anecdotal:
A guy at work said to me "when you get to my age", I asked him how old he was and he said 48. I said I had five years on him. Looking at him I think I have more wrinkles, but I am definitely more robust. Hormones, exercise and diet probably push these set points up and down a bit.
I think it's also interesting how different people assign different physical attributes to age, like in that example above, wrinkles vs. physical characteristics.
Organ Proteins Reveal How Aging Accelerates at 50 Years Old | Scientific American
https://www.scientificamerican.com/article/organ-proteins-reveal-how-aging-accelerates-at-50-years-old/
>> "when you get to my age",
I get that a lot. Even more surprisingly, people occasionally tell me to "enjoy it while you can, because you won't be able to do that in your 50s." Last time it happened, I told my wife: "Poor you! Thank God I'm not in my 50s. Don't worry, in a couple years you'll be okay too."