Runs/ Day: Single Vs. Double Approaches to Training

[Benn Griffin]

I am just curious what has been shown to work best in training for marathons. Single or double runs per day. I don't know about everyone else, but my schedule usually only permits one run per day, but it seems a lot of people operate on a 2 a day schedule. Do you get the same aerobic benefit from doing 2 x 6 mile runs in a day than doing one 12 miler? I am just curious. Can I still see improvements in my times if I am only running singles and logging 35 or 40 miles a week? I just want to stay away from the high end mileage because I am afraid of reinjuring myself. Can lower volume still effectively condition the body to the wear and tear of a marathon? i.e. my previous PR was a lowsy 4:26. and my second marathon was only 4:31 I really want to shatter those. I am going to try to hold a base of 30-35 miles a week, but right now my long runs are only 8-9 miles.

[Jeff Linger]

A couple things. First, plenty of runners have had very successful marathons 35-40 mpw training. Just make sure you're getting your long runs in. Second, to some extent, miles are miles. Getting them in is more important than not. So get the miles in however your schedule allows. Third, doubles instead of singles, when the mileage is the same (2x's6 v. 1x's12) will yield 2 different results. Doing the single run will undoubtedly increase your aroebic base and marathons are primarily aroebic events. However, studies have also demonstrated that runners who did 2-a-days at the exact same mileage of runners doing 1-a-day decreased their lactic-threshold. Meaning that the pace at which they began to accumulate lactic acid in their muscles at a greater rate than they could recycle it was faster for those doing the doubles. What does this mean? In your case, especially given your schedule, I would recommend that you stick to the singles. It will provide you probably a greater benefit towards a lower over-all-time. However, if you have the time to get in a double each week this would provide you an added benefit. I would recommend that if you're doing a double though, that at least 1 of the runs should be run at an increased pace. I did a number of doubles this past season (I went about 6-8 weeks getting in 1-2 doubles a week) and found solid results from them. I usually put them about 5-6 hours apart and the first one was generally longer than the 2nd with the first at a quicker pace. That was the plan, at any rate. Generally I found that my second run, given its shorter nature, ended up being at about the same pace as the first. I think it was just a natural inclination for my body to go faster knowing it didn't have to go as far. I would recommend fighting this urge and using the 2nd run as a recovery run at about 30 seconds/mile slower than marathon pace and the first at marathon pace or somewhat faster.

[Paul Petersen]

See previous thread on the topic:
http://fastrunningblog.com/forum/index.php/topic,228.0.html

Typically I do my easy days as doubles, and my workouts days as a long, hard single. A balance is beneficial. However, you also have to balance running with life, so doubles may or may not be worth it.

[Bonnie]

In my opinion, if you are planning on running 35-40 mpw then doubles would probably not be as beneficial as single longer runs.  I have found I am less injury prone when I build mileage more than 50 mpw in doubles, but I have read many articles/books suggesting this is the case when you hit 70 mpw.   I think the discrepancy is in counting miles and not "time" (for slower runners like me there is at least a 2 minute/mile difference in "easy pace" - which adds up over the course of a week) -- so, it can be interpreted as: doubles could make it easier (on your body) to increase mileage if you already run about 8-10 hours/week in singles.  I am sure there are other benefits (reference to Tinman's article about running efficiency), but my main concern is keeping injury free while trying to increase mileage.

Personally, I think a few months of slowly, gently increasing your mileage (at a slower speed) will allow you to run more miles without injury - meaning I don't think you will be limited to 35-40 mpw, which will be more conducive to a faster marathon.  But, you will have to be patient (and not look at the mileage board as often  ). 

Paul's schedule is interesting -- Brad Hudson suggests this (doubles on easy days and workout days as a single) - but Jack Daniels (and by extension my coach) and others prefer to have doubles scheduled on the same days as harder workouts.  And then there are many other elites, who run doubles (or even triples in the case of some of the Kenyans and Ethiopians) every day except for their long run days.

[Benn Griffin]

It's so hard though. I just want to go out there and run like 45-50 mpw and be back where I was last year My heart and mind say DO IT LETS GO! But at the same time I don't want my body to go "NO NO! I SAY STOP!" and crap out on me again