Yea, when I was a kid, like 10-15 years old, I did quite a few big drops, not as parkour, just as fun. I'm sure a lot of you older Traceurs on here did big drops when you were kids. I think it's a pretty common activity of adolescent boys to jump off things. I was just a thrill seeker, doing jackass kinda things, I BMXd and skated and whatnot ya know. I even fell off a 12 foot roof onto my back when I was 15. I had numerous lower back spasms while riding my bike and once snowboarding.
I'm 20 now and in the past year I've had two severe back spasms, which leave you in agony for a week (these were prob brought on by weightlifting at the time, but I certainly have a predisposal which im getting to) and then in minor pain for the following month, limiting your physical abilities. My MRI results showed numerous disk herniations, spinal stenosis, and degenerative disks and facet disease. They also showed a birth abnormality in my back, which apparently 30% of the male population has, called a "transitional vertebrae".. which basically changes the biomechanics of your back and just leaves you a little more likely to getting a back injury. All that aside, the docs said my back is basically fine with the exception of one moderate disk herniation(which pinches a nerve and causes my right leg to be numb) and that physical therapy should make everything better. I've been in it for two weeks now, and it's been 3 months since the last spasm, and my back pretty much never hurts, even while doing parkour.
MY POINT is... that my back probably got like this from all the stuff I did when I was young, and perhaps from all those drops. Also, if 30% of males have a transitional vertebrae, that means you could have it too, leaving you predisposed. Dealing with my back the past year was really shitty, it slowed down all my gym training, it's slowed down my parkour training, it f#cking hurt, it's made me depressed, and it just sucks, and it's not even THAT BAD of an injury. and it will come back to haunt me if I don't condition the f#ck out of my core
So, a few big drops when you're a kid are not the end of the world, as I'm sure tons of the older Traceurs played outside as children and jumped off things, it's just what boys do. I say this just so that older guys who knew they jumped off things, don't suddenly get mortally terrified of loosing their knees tomorrow. BUT if you're still really young, do yourself a solid and avoid the big drops.
Us older Traceurs can't undo the damage we may have done as kids, but if you're a kid now, you can. And that means the future of parkour could be a bunch of Traceurs who never damaged their bodies as kids jumping off stuff, and then they can excel further than we ever thought.
Thank You.