I sometimes confuse people when they ask me how many times I run per week and I tell them that it’s usually somewhere between 8 and 10 times.

It’s hard to grasp for some folks that there are occasions when you might want to run 2 or even 3 times in the same day (not that I do that very often.)

Two weeks ago I answered Tom’s question about whether it is better to take an easy day or a rest day for improved recovery.

His original email actually included 2 questions, however, so here is the other half:

I do have one question regarding a marathon training plan. I’m targeting the Chicago Marathon this October with a goal to break 3:00. In looking at the various sources of training plans, I see quite a bit of variety in terms of the amount of speed work.

When building up mileage, is there as much benefit in two 4 miles runs (one in the AM and one in the PM) compared to one 8 mile run?

The choice between running singles (1 workout per day) or doubles (2 workouts per day) isn’t an either/or type of decision; it all depends upon what your goals are. In general, I’d opt for a single workout most of the time if I have a choice when I’m training for a marathon, because you will get more of an endurance benefit out of it.

However, that is not always practical given a busy life when you have to work 8 or 9 hours per day and when you want to spend time with your family, so the only way to get 8 miles in might be to go out for 2 runs of 4 miles.

Another reason I might split runs up is if I want some high quality work (especially an afternoon speed workout) and need the run in the morning to get my legs stretched out ahead of time.

If I’m going to try to work all day and then go straight into a speed workout, then it can sometimes be a little easier if I do a short and easy run in the morning, especially if I did some sort of tempo or long workout the day before. (This is especially relevant when I doing high intensity workouts and training for shorter distances where endurance isn’t the key muscle adaptation that I’m trying to create.)

In other words, it’s better to do the full workouts when you can, but it’s better to do double workouts than to skip a workout entirely (unless of course you need more rest than was called for in order to avoid getting injured, but that’s a separate topic.)

(Photo Credit: Mike Baird)