Doubles…the dreaded “two-a-day”. Those phrases invoke not-so-fuzzy memories of high school cross country practice. Get up at 6AM, pound some stair laps, and then duke it out again on the roads at 3PM. Since most people on my prep team didn’t run at all during the summer, these double sessions (combined with racing three times per week) would “crash” most of us in shape by the conference and sectional meets.

Upon entering college and starting a new phase of my running career, doubles were completely eliminated from my training. Instead, our program focused on medium-length single runs (10-12 miles). My weekly mileage never topped over 80, which was not a hard volume to accomodate with singles, and I decided at that point that two-a-days were only for high school kids and obsessive-compulsive freakazoid runners.

This sentiment has changed, partially because I have become an obsessive-compulsive freakazoid runner. In other words, I become a marathoner in my post-collegiate running. Once my mileage reaches over 80 miles/week, I typically start incorporating doubles between 1-3 days/week. Here’s why:

1. This is a safe way to increase mileage without increasing pounding. It’s a lot easier to get 90-100 miles/week on 9 or 10 runs than on 6 or 7 runs.
2. Since runs can be shorter, you tend to get beat up less and reduce chance of injury (for the given training volume).
3. More running = more efficiency. Every time you go out and run, it increases blood volume and burns calories. There’s no such thing as “junk miles”. Doubles make you fast.
4. It’s a great way to recover from a race and do high mileage at the same time. For example, following up a half marathon or 10K with some doubles over the next week will allow the body to recover quickly and keep building aerobic fitness.
5. A short morning run is a good way to increase performance for an afternoon workout or race. Even an easy mile will help with this. I’ve found that running in the morning will help get the blood flowing and put some spring in my step for my evening run. It’s surprising how often I will wake up feeling slow and tired, jog with the dog around the block, and then feel like a new person when my evening run rolls around.
6. Doubles are a good way to keep mileage high on short race days. An easy 5-miler several hours after a 5K or 10K will keep your mileage stable and also “work out” some of the race soreness. Remember, easy is key, and running on a different surface is recommended as well (ie grass, trail, etc.).

At 70 miles/week or less, I don’t see much point in doubles, except on race days and recovery weeks. At 80+ miles/week, I think they are a good thing and should be considered by most people. If you’re struggling to get your mileage up, struggling to maintain mileage on recovery weeks, trying to lose those last few pounds of winter fat, or want a performance boost for workouts, give doubles a shot.