Back-to-back runs

This weekend I completed my first back-to-back run for my Highland Fling training. When you enter the world of ultra-running you will regularly hear about people doing back-to-back runs as part of their build-up to a race.  Some runners swear by them, especially as you increase the distance that you are racing, others don't really view them as having much benefit and stick to one (extra) long session.

 I've never really done them wholeheartedly before but it is one of the new training techniques I'm trying to apply this year.  Everyone has different views on what constitutes a back-to-back session. Huge mileage runners will possibly say you need to do a minimum of 2 x 20 miles on subsequent days. Others will say you need to just be in double figures on each day.

Here are my own rules for back-to-backs:

Both runs must take place within a 2 day time window.
Both runs must be double figures.
One run must be a minimum of 15 miles.
Total mileage for the two days must be 30+ mile.

This weekend I did 22 hilly trail miles on Saturday.  I ran this a lot stronger than I expected and blasted the final 2 mile descent to ensure my average pace was sub 10m/m.  Today I did a road run which I expected to be of a similar pace to yesterday due to the tiredness in my legs, but after an easy first mile my legs were feeling remarkably strong and I was able to sustain sub 9m/m for my run despite the shocking weather.  Overall it has been a really positive weekend of running, and helped me go over 50 miles for the week.  This is the first time I have managed this all year so I am really pleased.