You have 11 miles on your training schedule but due to life, your time has quickly dwindled down to 45 minutes. You have three choices: give up your run that day, run the fastest 11 miles of your life (ha!), or split your run into doubles.
Many mornings, just as this morning, I scrambled to get the kids prepped for school, get the mail together that had to be posted, charge the smart phone, throw the laundry in the wash and thought there is no way I have enough time to get my run in.
Later in the day, I ran my double, 6 miles at a faster pace. Does this count as 11 miles, then? Absolutely! There are even benefits to running doubles, as mentioned in RW:
In this article, Ed Eyestone recommends twice a days to get faster, sooner. It gives you the benefit of running on tired legs on the second run and lets you get more miles in, which is the only way to become a better runner.
Even if this is not your goal, just getting out and doing something will help you mentally and physically. As we all know, getting out the door sometimes is the hardest part.
The only downside, double the laundry, adding to those wonderful chores. The upside, you will quickly get in great shape, both in body and spirit.