Work out with purpose when endurance training

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Matt Fitzgerald recently wrote on an interesting topic, asking: At what minimum volume does 80/20 training cease to be useful? I had some useful, common sense thoughts on the topic… that turned into the much longer piece below on endurance training, and how it must evolve past the basic runs consistent in most runners’ training plans.

First, to address Matt’s question… I think it’s important to consider the length of your goal event. Short of the marathon, I think it’s important during easier runs to practice running the duration or distance you plan to run your goal race, to accustom your body to the volume of running required.

For shorter events, this is easier. A 5K (3.11 miles) takes most runners 20-40 minutes, so it stands to reason you should be running at least 20-40 minutes or about 3 miles in easy runs. Doing 1 mile or 5 minute runs aren’t going to help you much at all. Hal Higdon has the right idea for beginners: Just work on running easy as long as you can uninterrupted until you can run 3 uninterrupted miles. That task in itself will suitably occupy most if not all of your training for such a race.

Something longer like a 10K (6.21 miles) might take more like 40-60 minutes. Even if you don’t run 6 miles regularly, running 40-60 minutes regularly in easy runs is probably a better idea than just brief 2-3 mile runs. Even your easier runs should have some specific application to the distance or time you plan to race.

It becomes more complicated running a half marathon, marathon or more. A 13.1 mile Half requires around 90-150 minutes of racing for most. Obviously, it’s not reasonable for most people to run 2 hours or 13 miles everyday. And of course the marathon requires a limit-busting 26.2 miles, and can take several hours. No one in their right mind will ask you to run that much.

The 60 minute race threshold is where a trainee should cease trying to run the distance in easy workouts, and focus instead on aerobically beneficial workouts:

Every workout should have a useful purpose, even your easy ones. “Just getting a run in” doesn’t count unless your goal is general fitness (in which case there’s a number of other exercises you can and should do aside from running). When you’re training for a race, your easiest workouts should ideally develop some of your ability to run that particular race.

So, going back to training for longer races, I’ve previously mentioned the aerobic sweet spot: The peak aerobic benefit from a run is gained during the 60th-90th minutes of continuous aerobic exercise. GA Dudley’s research in the 80’s showed aerobic development peaking at 60 minutes. Separately, it’s around the 90 minute mark where fatigue often begins to damage form and muscle.

Running long at least once every week or two is very important to developing the aerobic and neuromuscular capacity to successfully run a marathon. Long, for marathon training, is at least 90 uninterrupted minutes on a weekday, or at least 2 uninterrupted hours on a weekend. The slower you are, the longer you need to run: Your 90 minute run will cover far fewer miles than a 90 minute run by an elite runner, but both of you need to cover the same 26.22 mile distance on race day. You need to build a body that can run that race.

Beyond that, other training runs should accomplish one of two general things:

– Develop aerobic endurance capacity for use in the race
– Develop physical strength that will power your running and buffer your body as it tires

You can do strength training with weights or other exercise methods like Pilates, but while generally valuable for health this has a limited positive effect on your running. Its value depends on your posture and overall alignment. Sometimes, strength training only develops you within your imbalances rather than correcting those imbalances.

Ditto to some extent strength/aerobic fitness sessions like Zumba, OrangeTheory, dance classes like modern or ballet, etc. I actually think these are great for developing overall race fitness, provided you take a rest day or two after doing a session.

However, each method optimally develops a very specific form of fitness that is not running a marathon. It can provide some benefit to your run training, but will not train you for the race anywhere near as well as running itself.


I digress a bit, but at least what I mentioned does fulfill the key criteria: That a workout should specifically develop some of your strength and/or aerobic capacity to help run your goal race.

There comes a point where your short 2-3 mile runs aren’t helping you train for a marathon at all. Miles in themselves aren’t always good for your training, and it’s actually one of the toxic problems with training tools/groups/apps/etc that place a premium on the number of miles you run. Many ill-advised trainees think that going on any run at all is good during a marathon training cycle because it’s more miles.

If you’re generally working out or training with no goal, that would be completely fine. Run however much or little you want. They might even be fine when training for races up to about 10K.

If you have a goal to run a marathon, these little easy runs are not good, and should be curtailed or eliminated UNLESS: You know for sure that a short run helps you recover after a longer/harder workout, in preparation for the next longer/harder workout.

Still, doing short easy runs for recovery can be risky, akin to the advice that an alcoholic drink in moderation can be good for you: Some with more habitual drinking problems mistake that as a license to drink whenever they want, then blow past a very specific and low threshold of benefit to where they do way more damage than good.

A recovery run is fine if the run actually does help you recover better than resting, especially if you need the short run to recover properly or else you won’t.


What if you’re like me and you need some sort of exercise everyday to be able to sleep well? What do you do on those days between quality workouts?

Often, you might be better off doing some sort of aerobic cross training instead (spin bike, elliptical, ARC Trainer, rowing machine, Nordictrack, etc), or even full body strength training in lieu of more aerobic anything.

Generally speaking, most would be just fine to follow the increasingly general advice to run 4 days a week, every other day except for the last run, which is followed the very next day by a long run, followed by a rest day. Such a schedule looks like this:

Monday: Run workout
Tuesday: Rest
Wednesday: Run workout
Thursday: Rest
Friday: Run workout
Saturday: Long run
Sunday: Rest


That said, unless you’re a novice or someone inexperienced with running, you want each of those run workouts to have a certain purpose other than just be several miles of easy running.

A novice is fine to simply run any amount of easy miles as much as they’re able/willing, for developing aerobic endurance. However, virtually all experienced runners already have the aerobic capacity to easily run 45-60 minutes. A 30-45 minute easy run isn’t going to develop their aerobic fitness or neuromuscular endurance at all. At best they (maybe) maintain their existing fitness. No additional development is being made.

To train for any distance shorter than the half marathon, this might be perfectly fine. Once you’re training for a goal race longer than 10 miles, you need more than 60 minutes of easy aerobic capacity. In training you regularly need to either run longer, or to train harder in those workouts.

I don’t think you NEED to do track reps or tempo runs to train for a marathon. Yes, it certainly helps in most cases.

But IF you decide not to do any speedwork, then all of your training runs need to be 60 or more minutes. You need to hit the 60 minute aerobic sweet spot for mitochondrial development, and consistently get as close to the 90 minute neuromuscular threshold as you can.

If you’re a novice and/or lack the aerobic and neuromuscular capacity to regularly run more than 60 minutes easy, then your first task in training is to work up to 60 minutes of everyday easy running and get used to it. THEN from there you can work on stretching out the length of the long run, and perhaps your weekday runs if desired.

Again, that is IF you don’t want to do other quality training workouts like speed reps or tempo work. If you want to run harder than an easy/moderate intensity, then you can shorten the running length.

If you’re training for a marathon but don’t have the time to run more than an hour on the weekdays, then to be successful your hand is kind of forced. You need to do at least some faster/harder running in your shorter weekday workouts.


That doesn’t mean any easy workout that’s less than 60 minutes is pure garbage during endurance training for long races. Again, recovery workouts can be valuable.

But, unless you know for sure that you only recover best if you take a shorter easy run on days between your longer/quality workouts, you may be better off either:

– Resting completely, maybe going for an extended walk instead of working out
– Doing aerobic cross training, which is lower stress
– Doing strength training, if it doesn’t interfere with lower body and core recovery between workouts
– Doing an aerobic exercise class, if it doesn’t interfere with lower body and core recovery between workouts

Meanwhile, for those key workouts shorter than 60 minutes, you need not do an absurd volume of speedwork or tempo work. You need not find a track and do a bunch of 400 meter repeats, or kill yourself with a 30 minute uninterrupted tempo run, if that doesn’t work for you.

You can do something simple, like:

  • A fast finish run, where you run easy most of the way, then run harder for the final 10-15 minutes.
  • A hilly run, where you do an easy run but in a place with several relatively challenging hills.
  • A fartlek-style run: Start with a few minutes of easy running. Then, run harder than usual for 1 minute. Then run easy for 1 minute. Repeat that cycle until you’re done.

All of these do far more for developing essential endurance fitness than an easy 30-45 minute run.


So, to conclude, let’s go back to the Matt Fitzgerald 80/20 question he raised. What’s the minimum volume of 80/20 running needed to be beneficial?

I’d recommend:

If your goal race is shorter than a marathon, your total weekly time spent running should be at least 3 times the length of the race you’re going to run, either 3 times the mileage or 3 times the likely length of time.

So, if you were running a 5K and knew you could run it in 24 minutes… you you need to train a minimum of 72 total minutes per week, or 9.32 miles/15K (three times the distance of the 5K) per week, for 80/20 training to benefit you. Any shorter, and you reduce the likelihood that you will be ready.

At the marathon and ultra distance, you should run at least 6 hours per week. (I know in his book 80/20 Running that Matt Fitzgerald himself prescribes shorter marathon workout weeks. But, in my view, this is the amount of training volume essential to developing the ability to suitably run the marathon.)

Cross training: Fitzgerald’s 80/20 Running method assumes all running, though he’s generally permissive towards cross training in lieu of some runs. As many do, his advice on cross training volume is somewhat general, but I’ll give some specific guidelines:

In both cases, you can cross train, but for any running you replace you need to add in more cross training because of its lower intensity. My rule is to add 20 extra minutes of cross training for every hour of running it replaces. For example, want to remove 60 minutes of a day’s running for cross training? You should do 80 minutes of cross training, whether you do it all at once that day or split it up elsewhere during the week.

It’s an interesting question, and by no means do I consider my answer final. That’s my guideline based on my experience with myself and others.

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