Earlier this year, my teammate Dave wrote a post regarding doubles, and why he thinks they are the worst idea ever. I personally disagree with him in theory. Splitting a run into two smaller pieces makes a lot of sense to me, provided that your long runs stay long. The day after a hard workout or race, the idea of running two 30-minute recovery runs sounds much gentler and easier than running a single 60-minute run. Also, splitting a run up can even result in more mileage than you would otherwise run. For instance, I probably would not run more than an hour the day after a hard workout. But, if I run for 30 minutes in the morning, and 45 minutes in the evening, that yields an extra fifteen minutes of aerobic work that I otherwise would not realize, and each run is still less than I would ordinarily do in a single session.
For this reason, I start out almost every training cycle incorporating doubles once I start running 60 miles per week or more. I keep a long run every week, and typically only run once on workout and race days, but most other days I will run twice. I enjoy the added mileage and being able to run less in a single outing than if I were only running once per day. This wonderful relationship with doubles usually lasts for a month or two.
Once I start hitting really hard workouts, however, I quickly realize that running twice a day just doesn’t work for me. Every cycle for the past five years or so, I switch back to only running once per day halfway through. Even though the idea of doubles sounds really great to me, it is obvious that my body responds better to having a full 24 hours between runs, even if those individual runs are longer. I recover better and feel fresher running one easy eight-miler than I do running two easy four-milers. This is true whether I am training to run a fast 5K on 50 miles per week, or running 90mpw in preparation for a marathon.
This anecdote just serves to prove that while science can suggest one training philosophy over another, and some runners swear by their individual approach, everybody is an experiment of one. Almost all elite runners incorporate doubles into their training, and it obviously works for them. As I have said before, I am not elite. Because of that, it is foolish to think that I can train the same way as an elite. One of the reasons I am not elite is because my body doesn’t allow me to accept and tolerate the training workload that a world-class athlete requires. I don’t run 2:05 for the marathon, so why should I run 140 miles per week on doubles like a 2:05 marathoner does? I have found what works for me, and that is what the goal of every runner should be. Experiment with different training regimens, and decide what you like. It may take some time, but in the end, only you can determine what is best for you.