We often joke about old age and the pains of same at the dojo, especially when teenagers start complaining that their hips hurt. (No, really. They do.) One of our instructors, now in his very late 20s, likes to shoot back that he's in fact able to relate to our middle-aged issues because his age in karate years is closer to ours (he's been training hard since he was a little kid).

It's a fascinating topic - at least, we think so - and this interesting video helps understand what happens to you when your cells regenerate. There is, however, much more to it than that.

I am constantly amazed at how non-resilient some of the kids are. They seem to get injured a lot - tendons snap, bones break, muscles tear, joints sprain - and to me that's more than just a little odd. Because when you're young (say, before you get to the dreaded two-oh), your body is still growing, your metabolism is going full-tilt, you're full of beans and energy.

Right? Well, apparently, not quite. There's a lot more breaking down than I remember from my youth wayyyyyy back in the 1980s. I spent a lot of time doing sports, and hanging out with competitive athletes (including at least one who made it to the Olympics and one who made it to the NHL), and I do not remember them getting hurt so often. And that's an unpleasant puzzle. Because if those athletes get so injured so easily at 16, how are they going to make it to their 40s and beyond?

I blame the food they eat (too much processed empty junk filled with hormones and antibiotics) and the sleep they're not getting, but maybe that doesn't explain all of it. I don't know. What I do know is that I eat an absolutely freakishly clean diet and try to get my beauty sleep as much as I can and that seems to work. I'm 45 (and a half), I train 15-20 hours a week (plus the biking and swimming I do for fun), and while I'm always sore or stiff somewhere, I do not, so far (knock wood) suffer from injuries. And I am intimately acquainted with repetitive stress, believe me.

It's a bit of a puzzle, and I'm not the only older person who worries about it. Something is making the kids' bodies older than they really are, and that's something we should not take lightly.