Oh geez, two of the people who went with me to the Yosemite backcountry last month are into their 60's and took lead most of the way. Neither is slow. They're considering either a return to the Dolomites or a couple of weeks in the eastern Sierras (depending on mood and budget) late in the Summer and another trip into the mountains of Montana or Wyoming just before winter. Both allow that it was lightweight gear that allowed them to really do this stuff, but there's no question that they've got a lot of miles ahead of them. It's getting hard to think of 60 as "old," at least in backpacker terms, any more.