TELLMENOW wrote:
My coach would tell me it's a horrible idea and that I would get injured...which I why I have doubts. So if someone could tell me what it will do for me then that would be great!
Running twice a day enables your body to recovery faster. You get used to running with half as much recovery in between runs, and over time your body adapts. I don't think I really need to elaborate on why faster recovery would be beneficial to running.
Additionally, it allows you to run more mileage. This has been brought up 100000 times on LRC, but the point of doubling is not to do 5 and 3 instead of 8, but to do 8 and 3 instead of 8. In the end, the more time you spend practicing something (in this case, running) the better you will get at it. 6 days of 8 miles and a long run of 12 gets you 60 miles. Toss in 5 days of 4 mile second runs and you hit 80. I don't think there is a person on this board that would disagree that 80 > 60 (assuming you build up reasonably and can handle it, aka don't jump from 60 to 80 in one week).