block training

How Block Training Can Help or Hurt Ultramarathon Training

By Jason Koop,
Head Coach of CTS Ultrarunning

Let’s face it, training can often be boring. You do the same routes and there’s only so many ways you can (correctly) contrive workouts. You wake up, run, eat, go to work, rest, rinse, repeat. Most people have some vague pattern of run hard one day, run easy the next, run hard the day after that and so on. Do you ever ask yourself, “Why do I need one day of easy running after a hard day?” Most people don’t. Like lemmings, many runners will blindly follow this hard-easy-hard pattern week after week after boring week. The main (modern) influencer of this pattern comes from the collegiate cross country and track and field programs, all of which have some nebulous regurgitation of the following weekly structure:

Monday- rest
Tuesday- Track workout
Wednesday- Endurance run
Thursday- Tempo run
Friday- Easy run
Saturday- Race or another tempo run
Sunday- Long run

traditional training

But it does not have to be this way. This hard-easy-hard workout pattern does not have to rule your running life every-single-week of every-single-month. If you want to spice it up (as much as running workouts can be spiced up), you can consider block style training from time to time. With it, you can challenge yourself in a unique way and at the same time, reap additional gains out of the same amount of work and not contrive your day to day workouts with cutesy names simply for the sake of entertainment.

Block training basics

The term ‘block training’, like many training terms, is actually ill defined. So, I will take a few sentences to give it context before going any further. In most endurance applications, block training refers to either-

  • Doing the same type or intensity of workout for several weeks at a time.
  • Doing back to back hard days, regardless of the specific intensity

The first version of block training is the style you see in Training Essentials for Ultrarunning. I feel that that style of training, where one type of intensity (or a narrow range of intensity) is the focal point for weeks at a time, is more effective for experienced endurance athletes. And let’s face it, just about all ultrarunners are experienced athletes in this context. That’s not going to be the focus of this article though.

The second version of block training is where you do back to back hard days every so often. These days can be of a similar intensity, or a harder intensity but for the purposes of simplicity, I am going to discuss when the back to back workouts are of a similar intensity for this particular article.

Why should ultrarunners try block training?

Interestingly enough, most ultrarunners are already familiar with the concept of block training in the form of back-to-back long runs. They do these runs with the intent to ‘run on tired legs’, which to be honest I don’t think ultrarunners understand very well. Learning to ‘run on tired legs’ in training speak is simply improving your kinesthetic awareness. Meaning, any improving you make is simply rooted in becoming aware of the sensation you might feel in the late stages of an ultra. Whether or not that is valid is another discussion all together.

The real reason back to back long runs can be so valuable is that they concentrate a large amount of training load in a short period of time. This is not similar to a training camp or even a course recon of a few high mileage days in a row. That concentrated training load is essentially worth more benefit in the entirety of the training picture, even when you normalize for the number of hours you do in a month. For example, take a 14-hour week of training where you run two hours a day, every day (I am making the math easy for my own sake). Now, shift those 14 hours to be 6 hours Monday through Friday (1.2 hours per day) and 4 hours each on Saturday and Sunday. You are doing the exact same amount of time, just distributing the volume in lopsided fashion over the weekend. Almost undoubtedly, the latter version of that plan will lead to bigger adaptations.

The research teases this out as well. Time and time again when researchers pit training plan interventions from athletes that are evenly spread out (like in the hard-easy-hard or the 2 hours per day example examples above) vs training plans that concentrate the hard work (either on back to back days or a more lopsided frequency) the concentrated block training wins out. The block style training will produce bigger physiological improvements (VO2 max, pace/power at threshold, etc.) as well as better real word performances (time to exhaustion tests, time trials, etc.). It does so even when the workloads (total time, time at intensity, number of hard workouts, kilojoules of work, etc.) between the ‘normal’ and block style conditions are equivalent. Meaning, you quite literally get more bang for your buck. You get bigger results from the same amount of time and the exact same workouts, by just changing the pattern.

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Why block training works

I promise, it’s not a magic trick nor a free lunch. Very rarely (if ever) do those exist in training. Quite simply, block style training works because the acute stress over the ‘blocked’ period of time is bigger, although the overall workload is the same. And a bigger stress on your body will always lead to bigger results when done properly (big caveat there). As with most training related studies, it is hard to tease out precise mechanistic responses of why a concentrated training load is superior to a peanut butter spread training load, even when the workloads are equivalent. Yet, the end result is the same and I’m honestly hard pressed to find compelling research to counterpoint this. Seems great right? You do the EXACT same workouts, just in a slightly different order and achieve better results. Before you jump on the bandwagon with reckless abandon that is oh-so common in ultrarunning, read on.

Why block training isn’t for everyone

Before you jump into the deep end, consider the following. My best educated guess is that if everything goes right with your newly adopted block style training program, you might be ~2-6% better after a significant period of time (like a season or a year) compared to a similar non-blocked style of training. That’s significant, but pales in comparison to the overall improvements you can make by simply being consistent, doing some intensity, getting enough sleep and having a reasonable training strategy. So, consider this an advanced training strategy you should only implement if you’ve already picked, eaten and reaped the benefits from the lower hanging fruit. Here’s a checklist for you to run though before you consider a block-style option:

  • Are you still making reasonable improvements with your training? If so, you are not a good candidate. You should consider block style training if your improvements have started to stagnate and you are already incorporating adequate rest. Interestingly enough, some of the research refuting block style training being superior to traditional style training has been done on junior athletes, indicating that regardless of the training stagey, they have so much room to improve they will do so anyways (McGawley 2016)
  • Do you have a history of injuries (>1 every 9 months). If so, I would not take the risk. Increasing acute training stress has a history of resulting in increased injury rate.
  • Can your running lifestyle accommodate two back to back hard days? Interestingly enough, at times when I’ve proposed this type of training to athletes it inevitably results in some sort of social conflict (‘But my pub run is on Wednesdays!’). If you can’t deal with this radical lifestyle change, block training is not for you.

However, if you fit the criteria for block training, and if you are up for the challenge, here’s how you can safely and effectively incorporate block style training into your routine.

How to execute block training

Incorporating block style training is actually far easier than you think. It takes a bit of planning, but with some pen and paper and outside the box thinking, it’s far more of a reasonable prospect than it might appear. First off, realize that you are doing the exact same amount of work over an entire phase (3 or 4 weeks for most people). You are not increasing the length of your runs, length of your long run, number of workouts, length of intervals or anything of the sort. Quite literally what you are doing is taking the same work you would have done and rearranging the days.

Your first step is to draw out 3-4 weeks of training like you normally would, beginning with the week after a recovery week. After that, all you need to do is rearrange the hard workouts such that the first, and maybe second week contain a disproportionate number of them, even if they occur on back to back days. I have given a very simplistic version of that below. Note that each schedule contains the same number of hard workouts. I have also stylized the workouts to simple categories; hard, easy, endurance and rest in order to illustrate that you can do this across any intensity of workout. The only difference is that the block style training concentrates the hard workouts at the beginning of the phase.

block training

More caveats

As always, here are some more caveats if you are trying to do this yourself.

  • Hardest workout first. This style of training works best where the specific time at intensity decreases as the phase goes along. I wrote about this in this blog and the same principle applies. You want to do the highest workload when you are freshest.
  • Hardest workout first, part deux: If you do end up doing a back to back day, the first workout should be the harder of the two.
  • Do not increase the total amount of time or miles you would normally run. That’s kind of the whole point. You keep the total workload the same, and just manipulate the frequency.
  • Don’t get too fancy. Sure, there are ways to do this where you do a RunningInterval workout the first day, then a Tempo workout the next. But, if you are just starting out with this style of training, stick to the basics!
  • Somewhat surprisingly, most athletes will have an easier time adjusting to a back to back day during higher intensity workouts (800 meter or 3 min repeats) vs. longer intervals (2 mile or 15 min repeats). So, I’d start with RunningIntervals if you are unfamiliar.

Author’s note. I also wrote a bit about this topic in this month’s edition of Ultrarunning Magazine. Feel free to check that out as well. 


  • McGawley, K., et al. (2017). “No Additional Benefits of Block- Over Evenly-Distributed High-Intensity Interval Training within a Polarized Microcycle.” Frontiers in Physiology 8(413).
  • Issurin, V. B. (2016). “Benefits and Limitations of Block Periodized Training Approaches to Athletes’ Preparation: A Review.” Sports Med 46(3): 329-338.
  • Molmen, K. S., et al. (2019). “Block periodization of endurance training – a systematic review and meta-analysis.” Open Access J Sports Med 10: 145-160.
  • Ronnestad, B. R., et al. (2014). “Block periodization of high-intensity aerobic intervals provides superior training effects in trained cyclists.” Scand J Med Sci Sports 24(1): 34-42.
  • Ronnestad, B. R., et al. (2016). “5-week block periodization increases aerobic power in elite cross-country skiers.” Scand J Med Sci Sports 26(2): 140-146.

Comments 5

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  5. Thanks for the great article Coach Koop. I love how you support everything with the research and give pros and cons. That is very important to inform my own decision about using block training for myself or prescribing it for my daughter’s training. Thank again, Jonathan

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