I am primarily a middle distance runner and I presume that I am more of the FT-type and that my aerobic capacity is lacking in development, since my times drop off rather dramatically in distances longer than 1500/mile. I’ve run as much as 75 mpw in the past and that helped quite a bit, especially at 5K and up.
Now I am thinking that in order to take my running to the next level I really need to take it up a notch in volume; however, I am also concerned that this could negatively affect my 200m/400m running abilities (I’ve heard that it’s possible for muscle fiber types to change over time… is that true?) Basically at this point I feel that it’s necessary for me to both lower my 400m time as well as my 5000m time, as I’ve never broken 50 for 400 or 15:00 for 5K, though I’ve never focused on either event or raced them very much.
So the question is will high mileage make me slower at very short distances?
And
What can I do to maintain short distance ability while increasing volume?