In one way or another injury will always slow you down. This may be voluntary or may be forced upon you by your body or doctor, but sooner or later injury will slow you down. Now, I am not saying you will definitely get injured, as there are some very fortunate runners that have remained injury free (I think a total of 2 of them). I also am not saying that the ultimate outcome will be that you are slower as that would just be an ignorant thing for me to say.
Injury just seems to be a part of running for most people. I know of very few people that have been able to avoid a running injury. If you spend any time on Facebook, Twitter, Blogs, or Dailymile you will see someone talking (or in my case whining) about being injured, dealing with an injury, or recovering from an injury.
