If you’ve ever looked at your training plan for an upcoming race and thought “I don’t have time to fit these miles in,” it’s not just you. Building volume for any training plan takes time, planning, and a flexible schedule—luxuries we don’t always have. This is where running twice a day can actually make getting all those miles in a little bit easier.

“When I've been training for something specific and needed to get the miles in, but had to fit the running around a busy schedule, I add twice-a-day runs to my schedule,” says Peloton instructor Susie Chan.

While running twice a day might sound like a feat for an elite athlete or ultramarathoner, it can also support the success of your goals for some recreational runners (when done safely). Below, score tips for how to successfully run twice a day and learn all the benefits doubling up on your training can have.

Is It OK to Run Twice a Day?

Like working out twice a day, it can definitely be OK to run twice a day. But whether or not it’s a good idea for you depends on factors like fitness level, goals, and amount of time you have to allow your body to rest between runs. 

“You definitely want to work up to it and ultimately ‘doubling’ is a method to incorporate more mileage into your plan,” says Abigail Warner, a doctor of physical therapy. “For example, when I ran in college, I would utilize doubles during my week just to increase my overall total weekly mileage.”

The Benefits of Running Doubles

If you have a busy schedule and don’t have time to fit in one long run, running twice a day can be a great solution. For runners working on endurance running (like training for a marathon, triathlon, or ultramarathon), or even training for a hybrid competition like HYROX, doubling up on runs can help you build your weekly mileage without the time commitment of one really long run and help you learn to run on fatigued legs. 

By splitting up your longer efforts into two parts and adding in a second run, when your body is a little more tired, it helps build resilience, Susie explains. She says she has incorporated doubles into her schedule when she needed flexibility but also had to build up her mileage during heavy training cycles. “I now often run twice a day, once for my own running, then I come in to work and run again,” she says.

Doubles can also help make you a more efficient runner. Running twice a day helps optimize your body's use of glycogen (i.e., glucose, a main source of energy stored in your muscles and liver) on your runs. By running a second time in the same day, you’re training your body to more efficiently use the limited glycogen stores you have left after your first run, and to effectively switch to other fuel sources, like fat. Further, a small study published in the Journal of Applied Physiology found that training twice a day increased endurance athletes’ mitochondrial efficiency (essentially, their ability to convert fuel to energy) and reduced their rate of perceived exertion (RPE) during training.

As Warner points out, running doubles is ultimately a way to increase your overall mileage, which is generally linked to increased running fitness and better race performance. Research published in the Journal of Strength and Conditioning Research, for example, found that among elite male distance runners, a higher total running distance and more easy runs were the strongest predictors of race performance.

Adding doubles to your training schedule may also be helpful for experienced runners who are injury prone or encounter issues when they run several miles consecutively. For example, if you usually end up with aches or pains after running five or more miles, you could try breaking up longer distances into two efforts, like a three-mile run in the morning and three-mile evening run, Warner explains. This approach allows you to increase your overall mileage and accumulate time on your feet while reducing the strain or pain that happens when you run for a longer distance in one go.

There are mental benefits too. Adding two-a-days to your schedule can give you a confidence boost. “You're training your brain to run when you're already tired and essentially training your willpower,” Warner says.

The Drawbacks of Running Twice a Day

If you don’t have a solid base or experience with running a lot of miles, or add in multiple daily runs too quickly, you’ll put yourself at risk of getting hurt and bringing your training to a halt. “Like with any uptick in more running, you’re opening yourself to injury if you don’t scale up the distance slowly and safely,” Susie says. And even if you don’t get injured, too much running may cause you to feel more fatigued or not allow for proper recovery.

Running too much may actually hinder your performance, especially the closer you get to race day, according to a study published in Sports Medicine. Researchers found that experienced marathoners who reduced the frequency of their runs during the final four months of training actually completed the Boston Marathon with faster times than those who increased or maintained training frequency.

Other drawbacks could include finding time to fit two runs into your schedule. Splitting up a long run into two may be helpful to some, but for others, it may be difficult to find time to head out the door for a second round of mileage. While running twice a day can help boost your willpower if done in small amounts, running too frequently has the potential to cause mental burnout, Warner says. “It can be very hard motivating yourself for the second run,” Susie says.

Who Should Be Running Twice a Day? 

Running twice a day can be very useful for experienced athletes whose training plans call for high-volume weeks. For example, an experienced marathoner training to improve their finish time might employ this technique during part of their training.

However, it’s important to note that running twice a day is likely not necessary for most recreational runners. Moreover, beginner runners shouldn’t try it, and intermediate runners should approach running doubles with caution. 

If you aren’t training for a specific endurance race, or if it doesn’t make sense based on your training plan, it’s not necessary to run doubles, and you can stick with your normal run routine, Susie says. 

How to Run Doubles Safely and Efficiently

Start with a Solid Base

Before you ever think about running doubles, you need to make sure you have a solid base. This means you should be running regularly for several months, at least two to three days per week. As you progress your training, you should increase your distance by small increments to help reduce injury risk. (One common rule of thumb is to increase your weekly mileage by no more than 10 percent at a time.) Once your long runs are up to 5 or 6 miles, you might consider incorporating doubles, but it really comes down to personal preference and scheduling, Warner says. 

Then, if your training plan calls for a lot of mileage, or splitting your runs into two sessions fits your schedule, you can start with a distance that feels very manageable to you for your second run. For example, if you have seven miles on your calendar for the day, go out for a five-mile run in the morning, then head out for the remainder of the distance (two miles) at night and build from there.

If you’re a beginner runner, it’s especially important to build a base before you add doubles to your routine. It can also be helpful to work with a coach to get a training plan tailored to your goals.

Watch Your Intensity

If you’re running twice in one day, both runs shouldn't be high-intensity efforts. For example, you could do a tempo run in the morning and a recovery run in the evening, or two easy runs spaced several hours apart. “You shouldn't be crushing your pace during a double,” Warner says. Limiting mileage and/or speed during at least one of your runs will help you recover properly and cut down on some of the strain on your body.

Susie suggests making the second run an easier one, whether that be a shorter distance or a slower pace, or both. “Getting the bulk of any work done on the first one will help you stay motivated to get it done,” she says.

It may help to think of your second run as a shakeout run or active recovery run, which can help flush out your legs and support recovery, Warner says. “I’m a morning runner, so I always tend to do my longer run or workout in the morning and then add in just a little shorter shakeout in the evening to flush any fatigue from the legs, get the blood flowing, and enhance my recovery,” she says. 

Give Yourself Time to Recover

It’s important to space out your runs as much as possible to give your body time to rest so you’re ready to log more miles without feeling fatigued. While it will vary by personal needs, you should give yourself six to eight hours in between each run so your body can maximize recovery time and you can perform your best during each effort, Warner says. You should also use this break between runs to refuel and rehydrate so you’re ready to head out for your second set of miles.

And you shouldn’t be running doubles every day. Generally, incorporating twice-a-day running two to three times per week is plenty for most training plans. “The second run is really meant to be more of an accessory run to increase overall weekly mileage,” Warner says.

Fuel Properly

Timing your fueling (both during runs and in between them) will need some extra thought, Susie says. You’ll need to be sure to properly fuel before and after each run, taking into consideration the distances you’ll be running and what you need to give your body to recover. 

“Make sure you are adequately fueling for the additional training, taking in enough carbohydrates pre-run and a good carb/protein balance post both of your runs,” Susie says. Additionally, hydrate and take in electrolytes as needed throughout the day to help your body replenish what was lost through sweat. 

How to Minimize Risks While Running Doubles

Incorporating doubles into your training schedule will definitely take a toll on your body, which means you need to be extra tuned into what it’s telling you, which might mean rest. If you start to feel any kind of niggle or pain, it’s better to skip the double that day than to push through just for the mileage, Warner says.

And sleep will be key to your success. Susie suggests prioritizing good sleep, especially up to two nights before you plan a double-run day.

You should also prioritize a thorough warm-up and recovery practices to help minimize your risk of injury, Warner says. Incorporating habits like a dynamic warm-up pre-run and foam rolling and stretching following both runs will help you continue to run smoothly and strongly, even on those double days.