Should You Run Twice A Day?

How two-a-days can help—or hurt—your performance
Staff Writer

By Jeff Gaudette—If you’ve spent enough time at your running club’s favorite watering hole, or happened to eavesdrop on a conversation between veteran runners, you’ve probably heard the concept of running twice per day being tossed around. Runners often refer to this practice as “running doubles”.

Doubles are a training staple for most elite athletes. I can’t think of an Olympic-level distance runner who doesn’t run twice a day at least a few times per week. Since two runs per day work so well for the elites, it’s no wonder that many competitive, non-professional runners will occasionally ask themselves: “Could I benefit from running twice a day too?”

Related–Running 101: How Often Should You Run?

It’s a fair question and the answer, of course, is very individual. Let’s take a look at the advantages and disadvantages of running twice per day and then analyze where you might fit in given your current training and racing goals.

Despite the latest fad a catchy magazine headline might try to sell you suggests, to run faster you have to run more. Running well at distances over 5K relies primarily on your aerobic endurance and development. Therefore, anything that a runner can do to boost his or her mileage will contribute to their overall aerobic development and progression.

1. Increased training benefits.
The primary benefit of adding double runs to your weekly training routine is that running twice per day puts your body in a glycogen-depleted state, which enhances training adaptations, especially if you’re training for a marathon. Scientifically speaking, studies have shown that glycogen content, fat oxidation, and enzyme activity increase when training twice per day. In moderation, this means you’ll get fitter faster.

2. More efficient recovery.
Running one 8 miler is definitely harder on the body than running two 4 milers. You don’t have to be a rocket scientist to know that training will be easier when you have the chance to rest and refuel in between runs.  Furthermore, since the purpose of an easy run is to facilitate recovery, running twice per day increases the frequency at which you speed blood, oxygen and nutrients to the muscles.

3. Easier to manage long training days.
For runners who are already waking up before dawn to get in their miles, adding more mileage to their morning routine might not be feasible. However, by incorporating double runs and turning your 8 or 10 miler into two runs–one in the morning and one in the evening–you can safely boost your overall mileage without being late for the morning commute.

Related—How Much Should You Run?

Interestingly, the same advantages described above can actually be disadvantages if you’re not an experienced runner with a significant aerobic base. Simply speaking, once you’ve been training at a high level for 3-5 years, the aerobic advantages of an easy run start to follow the path of diminishing returns. You still derive benefit from an easy 8-10 mile run, but not as much as a beginner runner whose aerobic endurance isn’t anywhere near its limit.

1. 60-90 minutes is an optimal for building aerobic endurance.
If you haven’t been running higher mileage (50 mpw) consistently for at least 3-5 years, the bulk of your improvements are still going to come from improving your aerobic endurance. Therefore, maximizing the number of runs you spend in the 60-90 minute range (widely considered to be the critical time threshold for enhancing aerobic fitness at the cellular level) is the most effective training method. Doubling will lend itself to more runs in the 30-45 minute range, which are still beneficial, but don’t increase endurance as much as a 60-70 minute run will.

2. Recovery can be hampered.
While easy runs do promote recovery by enhancing blood flow, they can also make you tired, as you’ve undoubtedly experienced at one time or another. If your fitness isn’t yet at a level where a 30-40 minute run barely leaves you breaking a sweat, the increased stress of a second run can actually hamper recovery instead of promoting it.

3. You feel like you’re training all day.
Running doubles requires significant dedication. It’s not easy to lace up the shoes twice per day, even if it’s only a few times per week. While I don’t think this would actually stop any runner from trying them, it can be a burden on your sleep needs, eating habits, and general attitude toward training.

Now that you’ve seen the advantages and disadvantages of running twice per day, it’s easier to appreciate what type of runner would benefit from incorporating double runs into their training routine.

Generally, doubles will benefit more experienced runners who have maximized aerobic development but still need to boost mileage without having their easy days be over 80-90 minutes. Or, they’re most beneficial for runners who are looking to recover more efficiently in preparation for harder workouts.

The chart below shows a brief breakdown of what type of mileage numbers you should be at before adding doubles to your training regimen:

When first adding doubles to your training, the primary goal should be to promote recovery. Therefore, you should add double runs before or after your hardest workouts. After you’re comfortable adding doubles to your workout days, you can then add them to your easy days, starting with your steady or medium long runs. For simplicity’s sake, here’s the order in which you should add doubles to your routine.

1. On days of speed workouts.
2. On days of tempo runs or cruise intervals.
3. On days of medium long runs or steady state efforts.
4. Easy days.

It doesn’t matter much if your second run comes before or after the main run for the day. Running in the morning before your evening track workout will help you loosen up and prime the body for a better effort–provided you don’t get tired. Running your double run after a hard workout will help flush blood, nutrients and oxygen to and from your tired muscles.

Some notes:
Running twice per day means you’re stimulating your metabolism more often and increasing the amount of calories you burn. Make sure you eat enough to properly recover and replenish the essential nutrients you need to keep making gains.

Give yourself enough time in between runs. Double runs are not as effective if you run them 2 hours apart.  Try to keep the time between runs to a minimum of 5 hours. I’ve found 7-8 hours to be optimal.


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