I recently was diagnosed with slight wear on two of my cervical vertebrae.
My only way to account for this damage has been 17 years of aikido, as I have not suffered any other traumatic insults to my neck.
Most of the time I have practiced aikido I have been technically obese (~33% body fat), putting me at about 246#. Coupled with my height, 6'1", I have to wonder if I was at particular risk for injury. None of my fellow aikidoka who have practiced as much have reported any issues. (Nota bene: none of them are obese.)
We have practiced on standard 2" blue mats, with no other shock absorbing elements.
And so I am bringing this issue to the table: Ought obese students be allowed to practice given the elevated risk of serious injury? I think this ought to be considered, especially in regards to break falls.
There is an African American sensei (forgot his name) who devised a falling technique to replace break falls. I have seen it being done and even try to learn it. My daughter learned it too but somehow no one remembers the Sensei's name. (shame). If someone knows to whom I am referring to, please assist. In the meantime, I will do some research. I think the Sensei had a similar problem with his back and hence devised the method. He has video out on that too. Perhaps that would help you now and also when you get more "mature" (old).