Is It OK to Split Up My Long Runs?

One of the hardest things about training for a marathon is finding the time to run all the miles it requires. This is especially true as the days get shorter but our schedules only get busier. Therefore, splitting up the long run, the bread and butter of marathon training, can be a good option (and safe option) for time-poor runners.

whitney running at dawn
Splitting up your long run can be a smart move for both your safety and training.

For many, especially busy moms with super busy schedules, finding 3 or more hours to run uninterrupted is like trying to squeeze your toddler’s jumbo puzzle piece into one of those tiny thousand-piece adult puzzle sets.

For many moms, including myself, getting in your longer distance runs requires waking up at like 3 a.m. to run before the kids’ sports or church. Getting up in the middle of the night, to run hard, and then be a busy, patient parent isn’t ideal. Then layer on top that skimping on sleep and over-exerting yourself, and you could be setting you up for injury and/or illness.

Why would you split up a long run?

Splitting your long run into two runs can be a good idea for runners who find themselves in this situation. For example, instead of doing a 20-mile run at o’dark-thirty on a Saturday morning, you could run 12 in the morning at a reasonable time and then 8 in the afternoon or evening. This allows you time to do things like sleep more and recover better, while still getting the necessary training volume in.

Related: The Scientific Benefits of the Long Run

I have had many athletes who were either short on time to do their longest run of the training cycle, or injury-prone, split up their longest runs to go on and perform well in their goal marathons or half marathons. By cutting their long runs into two, we ensured they got the necessary training and recovery time in to meet their goals.

Of course, doing your long run in a single long run is preferred. But there are pros and cons of splitting up your long run in order to fit it into your life schedule.

I got with exercise physiologist Todd Buckingham to go over:

  • Is it okay to split up your long run?
  • What are the pros and cons of splitting up a long run into two shorter runs
  • Who should consider splitting up their long runs, and
  • Best practices for splitting up your long run

Let’s get going!

Is it OK to split up your long run?

is it ok to split up your long run
Pin these tips for splitting up your long run for later!

Yes, it is okay to split up for your long run, especially if that means you will get the weekly mileage in instead of accepting defeat and not doing it at all. Training for a half marathon or marathon is a long way to run and takes a lot of time. If breaking the training into shorter work bouts allows you to do it, then do it!

Related: Can You Train for a Marathon on a Treadmill?

What does it mean to split up a long run?

Splitting up the long run for marathon runners or half marathon runners means breaking a long run mileage in two parts where you run the bulk of it in the morning (like 60 or 70 percent of the distance) and the rest of it (30 or 40 percent) later in the day or in the evening.

What are the pros and cons of splitting up my long run?

Splitting up a long run can be a great option for runners who aren’t able to run their long training runs due to time, injury, or fitness level constraints.

As Buckingham notes, “there is nothing ‘easy’ about doing a continuous long run. They take a lot of time, planning, and a good amount of fitness to be able to complete. The cardiovascular benefits of the long run really start to diminish after about 2.5-3 hours. After that, the benefits start to come more gradually along with increased risks.”

Still, completing a long run in one run does have pros including the confidence that you physically handle the distance in a single workout.

That said, here are the pros and cons of splitting up a long run into two separate runs according to Buckingham and myself.

Related: How Walking Can Make You a Better Runner

Pros of splitting up a long run

  • Splitting a long run session into two separate, shorter sessions can make it feel less daunting, especially for those training for their first marathon.
  • If you’re a time-starved athlete who can only run for a certain amount of time in the morning or at night, splitting the run can make the long run doable.
  • Splitting up the distance can reduce your injury risk and enhance recovery as your body is able to replenish glycogen stores.
  • Running a longer run in the morning, and a short run in the afternoon/evening may spur hormonal changes that can help with recovery.
  • Running a short run in the morning may help warm the body up for a longer run later in the day.
  • Can be a safer option for runners rather than running in the dark

Related: 5 Ways to Find Time to Run

Cons of splitting the long run

  • It takes more time than running all the miles at once because you must get changed, warm up, cool down, get something to eat, etc. before and after both runs.
  • You may not gain the mental strength or confidence to know you can complete the entire marathon distance without a break in between.
  • Runners may not get to train their gut adequately or practice proper fueling if both runs are shorter than an hour or hour and a half.
  • You don’t get all the same cardiovascular and muscular endurance benefits as you would if you ran the entire thing at once.

Let’s talk more about the physiological benefits you may miss out on if you split your weekly long run into two.

Related: Strength Training Guide for Marathoners

Do you gain less fitness if you split up your long run?

is it ok to split up your long run? Pros and Cons
There are pros and cons of splitting your long run into two runs.

Yes, you may gain less physical fitness if you split up your long runs in your training program. Let’s unpack that. Let’s say you split your two-hour run into two one-hour runs. 

Buckingham explains that you’re missing out on some of those physiological benefits that can be key for your races. This includes things like:

  • the body’s ability to oxidize fat as a fuel (which is extremely important in races lasting longer than 90 minutes)
  • improving mitochondria and capillary density
  • and probably most importantly the ability of the muscle fibers in your legs to withstand fatigue (i.e., muscular endurance or fatigue resistance).

I wrote an in-depth article on fatigue resistance as I learned personally how important it is for marathon success. After three years off from running due to injuries, I trained for about 5 months to run a marathon. My times showed I was fit for a sub 2:50 but my legs stopped working with 10 miles left in the race. This was because I lacked fatigue resistance which is built by doing lots of long runs.

“By cutting the run at 1 hour instead of 2 hours, the muscle fibers are able to recover between runs instead of having to withstand the pounding and other mechanical forces imparted on them for 2 hours at a time,” explains Buckingham.

“During the final miles of a race, it’s often not cardiovascular fitness that is the limiting factor; it’s the muscular endurance of the legs able to keep turning over at the same rate and with the same stride length. The long run is designed to help get you ready for those late miles of the race.”

That was certainly my experience.

Related: Running on Tired Legs: Cumulative Fatigue Explained

How does splitting up a long run reduce your risk for injury?

If splitting a long run has a huge CON of not bolstering the fatigue resistance as much a single run, then a huge PRO is that splitting up a long run can reduce your injury risk.

According to Buckingham, “the cardiovascular benefits of the long run really start to diminish after about 2.5-3 hours. After that, the benefits start to come more gradually, and the risks start to increase. The problem is that you can’t just keep running for hours on end and expect these benefits to continue to increase at a linear rate. Instead, it’s more asymptotical.”

This means long runs abide by the rule of diminishing returns. The rate of benefits starts to decrease as the rate of risks starts to increase.

pros and cons of splitting up your long run
Pin these tips for splitting up the long run for later!

Beyond the 2.5-to-3-hour mark, the risk of injury and over-fatigue also increase substantially, and your ability to recover may become impaired so that you can’t get another training run in within 24-48 hours, explain Buckingham.

This is especially important for time-strapped runners or injury-prone runners. If you only have 5 hours to train, it’s better to spread those 5 hours of training out throughout the week as consistency is what spurs your running fitness. Running for 5 hours one day and then rest for another 6 days isn’t going to get your fit. Running for five times for 1-hour will, however.

“It’s the accumulation of consistent training over the course of months to years. Not the one long run you do each week,” notes Buckingham.

Related: How Long Should Your Longest Marathon Training Run Be

Who should consider splitting up their long runs?

Splitting up a long run into two shorter runs can make marathon training more manageable.

According to Buckingham, who also coaches runners and triathletes, splitting up long runs is a great training option for:

  • New runners. Building up mileage safely to a long run takes time. For those just starting out, splitting the run can help get the mileage without the same injury risk.
  • Time-starved runners.Some runners might not have 3 consecutive hours that they can run during the day. Whether it’s getting enough sleep, family obligations, etc., splitting the run into two 1.5-hour runs can allow them to get the miles.
  • Slower runners. For runners who would take more than 4 hours to complete a 20-mile long run, splitting up a long run saves them from injury. As noted, the cardiovascular benefits of running longer than 2.5-3 hours are negligible. Splitting the run into two 2-hour runs can allow them to get maximum benefits.

Tips for Splitting Up Your Long Runs

  • Aim to run 60-80 percent of your total mileage in the first run. Focus on running with good form on tired legs in your second run.
  • If you can’t do that, aim to run more than half in your second run. Quicken your pace if you are able.
  • Avoid running longer than 3 hours in any segment of your split long run.
  • Aim to have at least one of the runs between 90-120 minutes long.
  • If you are going for a goal marathon time, your marathon plan should include pace work. That means one of your long run workouts should hav goal marathon race pace.
  • Don’t run both runs at a hard effort or medium effort. At least one or both runs should be run at an easy pace.
  • Try not to be on your feet or perform strenuous activity in between your two longer runs.
  • Aim to space the two runs anywhere from 4 to 12 hours apart.
  • If the second run is going to be done at a harder effort, ensure you have more recovery between the two runs.
  • Hydrate and eat well in between your runs.
  • Continue to focus on fueling and hydration for your long runs.
  • Don’t forget all your prehab and rehab habits to stay healthy!

I hope these long run tips help you get in your training and set you up for success on race day!

If you want a custom plan to fit your marathon goals with your busy schedule, check out my run coaching services. Also, be sure to check out my free training plans:


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