In reply to flopsicle:
I've had both office jobs (HR Mngr/trainer/) + outdoor jobs. (Scaffolder, tour/walking guide) and other stuff.
At 59 I decided to return to the UK and become the village Drystone Waller and Hedgelayer. I'm now 65 and when walling I shift around 5 - 10 ton of stone a day. I feel fitter than I've done for years. I feel I could crush stone and climbing tools with my grip now .
I am 100% that I cannot lift the heaviest stones first thing on a morning. So I do warm up but by lifting the smaller stuff first until I feel 'up to it'. Then I'm OK.
Luckily I don't feel tired at all, even on an evening. (just bragging there)
There was a study several years ago in the british army, which if my memory serves me correctly demonstrated that traditional warming up exercises did not prevent young recruits from injurying themselves during physical training.
That also ties in with comments made on this thread and from my own experience of being a scaffolder in my twenties. Certainly didn't stretch or warm up then!
I've met an 83 year old who is capable of extreme physical effort, and can still canoe white water and portage an 80lb canoe AND all the contents over the roughest portages in Northern Ontario in one carry. He doesn't look old or tough, and comes across as a gentle quiet unassuming man - which he is.
He's Fred Neegan a Cree hunter and guide on the Missinaibi River in Ontario. He's done it for his entire life and told me he has no intention of stopping. Needless to say he's a brilliant canoeist and can, and does canoe all day for several days when he needs to - and on white water.
http://i971.photobucket.com/albums/ae195/DavePerry/Missinaibi%202014/P10207...
The link should show a picture of him.