Splitting Your Long Run – Is Your Long Run Too Long?

By Rick Morris

The weekly or bi-weekly long endurance run has become the keystone training run for nearly all long distance training from the 5K to ultra distance running. Your long run plays an important role in improving your muscular endurance, mental endurance and central nervous system conditioning. Your long efforts probably also play a Zen like role in reducing your stress and improving your psychological health. Should you split your long run?

There’s no doubt that your long run is a valuable training weapon but is your long run too long? For years it has been assumed that longer is better. It has been thought that running longer distances will only make you fitter and stronger. Recently, however, there have been some coaches and distance running experts suggesting that you don’t need a singular long effort to prepare you for long distance racing or improving your fitness.  They believe you are better off if you split your long runs into two or more shorter runs.  It has even been suggested that very long training runs can be detrimental to your performance. They say that you will gain all of the benefits of a singular long run without the physical and mental stress. Do very long runs adversely affect your fitness and performance levels? Should you ditch your long runs?

In my many years of training, competing and coaching distance runners I have learned that there is no one answer to any training question that fits all. The question of splitting your long run is no different. In my opinion a singular long run is the best and most efficient way to train, but there are some occasions where splitting your long run is not only a safer and more effective long run technique, but is the only technique possible.

Benefits of Splitting Your Long Run

There are three primary benefits of splitting your long run; physical stress, mental stress and time requirements.

  • Physical Stress – Your long runs places a lot of repetitive stresses on your muscles and joints. The relentless pounding of mile after mile of running places a lot of demands on your body. Those demands are a two sided sword. On one hand, that stress is necessary if you are going to improve your endurance and strength. On the other hand, very long training runs place you more at risk of overuse injuries, over reaching and over training. Splitting your long run will help alleviate some of those stresses.
  • Mental Stress – Running very long distances can have two opposing affects on your mind. Some runners react very positively to very long distance runs. They take advantage of the time and physical effort involved to practice meditative skills and to become a more holistic runner. Other runners may react more negatively to the mental challenge of a very long run. Breaking the long efforts into separate runs can make long distance training psychologically easier.
  • Time Requirements – Typical marathon training long runs can range from 2 hours to well over 5 hours. Ultra distance long runs are usually even longer. If you have time challenges it can be difficult to find 3 or more consecutive hours to complete a long run. Splitting your long run into two shorter runs may be easier to schedule.

Benefits of a Singular Long Run

You’re probably already aware of the benefits of a singular long run but here is a quick recap.

  • More Goal Specific – One of the most important rules of training is the rule of specificity. This rule or guideline means that your training should closely match your goal. In the case of the marathon, you are training to run non-stop for 26.2 miles. Building up to a singular long run of between 21 and 23 miles, with part of that run at goal pace, is the best way to meet that training rule. Running two long runs of 10 to 15 miles each does a less efficient job of preparing you for 26.2 miles of nonstop running.
  • Superior Fitness Gains – Your body is able to store somewhere around 1900 to 2100 calories worth of carbohydrates in your muscles and liver. You burn just over 100 calories per mile of running. That is one of the reasons that you begin to suffer from high levels of fatigue at near the 19 to 21 mile point in your marathons. Long singular training runs of 20 plus miles will decrease your carbohydrate level to a point that a training stimulus takes place. Your body, mind and central nervous system all become more efficient at maintaining a strong pace when you consistently challenge your body with long training runs. Shorter split long runs don’t usually encourage a similar training response.
  • Makes You Mentally Stronger – You need to be a mentally tough runner to push through those final miles of the marathon. To train your brain to stay strong when highly fatigued you need to practice running when your body is carbohydrate depleted. Singular long training runs will do that, shorter split training runs will not.

Should You Split Your Long Run?

So, what is the bottom line. Should you split your long run? There are times when your must; times when you should and times when you shouldn’t. For example, ultra distance running requires a split long run. If you are training for a 100 mile run you can’t just go out and do a 100 mile training run. The recovery time after a run like that is too long for an efficient training program. In that case you must split your long run. For distances up to a standard marathon I would suggest sticking with a singular long run in most cases. But there are always exceptions. Below are my recommendations on when to split your long run.


Splitting Your Long Run

Goal DistanceRecommendations
5K to Half MarathonStick to singular long runs. Your long runs at these distances will not be excessive in length. Meeting the rule of specificity is very important at these distances.
Marathon - Less Than 5 Hour Finishing TimeI would suggest using singular long runs. Your training long runs will not be excessive in length. The fitness and mental benefits gained from singulars long runs will be worth the extra effort and slightly increased risk of over training or overuse injuries.
Marathon - 5 to 6 Hour Finishing TimeYou may want to consider splitting your long run if you are having problems with recovery, injury, illness or lasting fatigue. Also consider splitting your long run if you have time constraints or if you are having problems with long run motivation. Otherwise do a singular long run.
Marathon - 6 Hours or MoreYou are a good candidate for long run splitting. At this level your long runs will be very time consuming and stressful both physically and mentally.
Ultra Distance RunningAt this distance level, long run splitting is usually the way to go. If your ultra is in the 30 to 40 mile range, a singular long run is possible if you are at a high level of fitness and strength. For ultras of 50 miles or more, I would strongly recommend long run splitting.


Splitting Your Long Run

If you choose to split your long run there are a number of ways to do it. The best way to split your long run depends upon your specific situation. Here are some recommendations on long run splitting.

  • Morning/Evening Split – This is a good splitting technique for beginning and intermediate runners. I would suggest doing a 75/25 split with about 10% increased mileage. For example if your training plan calls for a 20 mile singular long run you would do a 22 mile run split in two. You would do 15 miles in the morning and 7 miles in the evening.
  • Evening/Morning Split – This is a more advanced splitting technique. The idea behind this split long run is to do an evening long run after dinner. Do not eat after your long run or before your morning long run. That will simulate a low carbohydrate situation without the stress of a singular long run. Split your long run 50/50 with a 20% increase in distance. If your plan calls for a 20 mile singular long run you would do 24 miles. 12 miles in the evening and then another 12 miles in the morning without eating between the split runs.
  • Morning/Morning Split – This splitting technique is not as effective as the above methods for up to marathon distance because of the long recovery time. This technique is often used effectively by ultra marathon runners. For distances up to a marathon, split your long run 50/50 with a 25% increase in mileage. A 20 mile singular long run would become a 25 mile split run with 13 on morning number one and 12 on morning number 2. An example of an ultra distance training run would be 20 miles on morning number 1 and 20 miles on morning number 2.
  • Micro Splitting – A very effective long run splitting technique is micro splitting. This long run technique is really a singular long run with extended recovery breaks, much like interval training. There are a number of ways to perform a micro split long run. A long run with walking breaks is a form of a micro split long run. You can also use complete recovery breaks rather than walking breaks. For example, if your plan calls for a 20 mile singular long run you could break your run into 4 x 5 mile segments with 10 to 15 minute breaks for hydration, nutrition and recovery. You can adjust your recovery breaks as you progress through your plan.