I think there are a few things that will affect it, mostly to do with the fact that the red blood cells carry the oxygen to the muscles to make them work.
If you have a good supply of red cells anyway, you will be less affected than someone who is, say, borderline anaemic, as you will still have plenty red cells left to do the job. If you run as slow as me, chances are the amount of oxygen the muscles need to propel you is a lot less than someone who can do 10 miles at eye-popping speed/effort. If your lungs and muscles are well trained to be as efficient as possible in transferring oxygen, you will feel less effect than someone who has trained less.
To sum up, suck it and see. The worst that will happen is that you will be slower than normal and be a bit more breathless.