Yes, no, maybe... It all depends on what you mean by "appropriate".
First, the themes and matters discussed in the book are suitable for an adult. If you were a teenager or child, things might be different but at 19 you should have the matturity to read whatever you chose.
Second, should you follow the advice given (if any) in the books is up to you. I would take it with a large grain of salt. Some of it might be good, some might be misguided, and some might be just plain stupid. If you do not possess critical thinking as a skill, it is high time you did!
Thirdly, if there are any training regimes within the book, I would urge caution in following them. They might be very suitable for him but not for you. Again, refer to critical thinking and your best judgement. The latter should include talking to medical and sport professionals.
Finally, more often than not, reading expands your knowledge which is always a good thing.