Last August, I wrote a post about the various theories of how to use long runs in training. The post was mostly about marathon training and the long run distances in several training programs.
While the August post mainly focused on the how, this post is about the why.
Before we look at the benefits of a long run, what exactly constitutes a long run? Most coaches describe it as a run lasting an hour or more. The distance you're training for and what constitutes your daily training will help you determine how far your long run should be.
If you're daily running is already close to an hour, a run lasting an hour isn't going to give you the same benefit as someone who runs 20-30 minutes several times a week. The article, "The Long View" gives good advice on long run distances. Two main takeaways from the article are that a long run should be between 1.5 and 2 times the length of your daily run, and that when deciding the length of your long run, use whatever is shorter--distance or time.
Long runs are not just for marathoners and half marathoners. If you're looking to run faster at almost any distance, a long run can help. In "The Many Benefits of Long Runs," Pete Pfitzinger describes seven benefits. Some of those benefits include an increasing your ability to burn fat, creating more capillaries for more efficient oxygen delivery and waste removal, and greater glycogen storage in your muscles. If you're interested in more details and benefits, I'd recommend checking out the full article.
Pfitzinger also mentions the spiritual benefit of running long. I agree. Even if you're not a religious person, running long is an excellent time to think and reflect.
I strongly encourage adding a long run to your weekly routine if you haven't already done so. Build up your distance slowly, and be patient as you begin to experience the benefits of the long run.