Didn't think so.
I'm no athlete, but I did the Iron Girl Try-A-Duathlon last summer, which had me run for 1km, then hop on my clunky mountain bike for 10km (about 6 miles), and then run again for 2.5km. I didn't set out to win, but just wanted to know I could finish. Was quite confident of the biking part as I had commuted almost daily for three years plus, but running was something I had to learn given that a few years ago I couldn't even jog half a block. No kidding.
Gradually though I built up enough endurance so that I could participate in a race just like this. Not a race of super long distances, or even that difficult for folk who run regularly, but enough to test the mettle of someone who exercises but doesn't consider themselves athletic.
So it begs the question of why the stereotype of the weak vegan persists despite the number of high-profile vegan athletes in just about every sport. And unless you're on an extremely low-calorie diet, or raw-fruit-only regimen (foolish IMO), or somehow not taking in enough calcium or protein from non-animal sources, you won't have weaker bones than your average sedentary meat-eating couch potato.
I mean, does it really look like the bones in my legs are gonna snap like twigs any time soon? Nope, my legs are damn strong, and even without a road bike my time on the bike portion of the race wasn't that much slower as my quad muscles have gotten a good workout over the years. If it sounds like I'm proud of this accomplishment, I am. I'll be turning 60 soon (which surprises most people as I don't look it), and don't know of too many other women my age, vegan or otherwise, who are still this active.
More importantly, having witnessed both my mom and other residents in her long-term care facility decline over the last year and a half, I can tell you that keeping mobile and keeping those legs moving however you can, is the best antidote for remaining independent. I really can't stress it enough: walk, walk, WALK. Or bike.
So go ahead, call us weak if you will, but the science and reality doesn't bear this out.