What percent of weekly mileage should long runs be?

My weekly long runs are more like 40% of my weekly mileage. Am I flirting with injury?

In my opinion, yes. You’re basically asking your body to do something for which it hasn’t yet adapted. It would be safer to get another short run or two in per week first to bring the weekly mileage up (but not too fast, for the same reason), and only then start to increase the length of the long run.

One way to look at it is to think about a marathoner who’s running 100 miles per week. Have you ever heard of someone like that doing a 40-mile long run? Experienced marathoners like @vedgund and @ChelseaB can chime in, but my understanding is that it’s unusual for marathoners to ever run more than 22-24 miles for a long run, and even then only once they have the weekly mileage to support such a distance.

The math is a little confusing, or, to me, it argues in favor of allowing your long run to be a bit longer than 25% of your weekly mileage:

Say you run five times per week. Then, if one of those runs is your “long run” and you want it to be 20% of your weekly mileage then your long run has to be the same distance as all your other runs. So what qualifies it as a long run? If you want your long run to be 25% of your weekly mileage, it can be 1/3 longer than your other runs. So if I run four times 4 miles, my long run can be about 5.5 miles. That hardly seems like a long run. If a long run is twice the distance of your usual run (which seems about right to me; my usual run is ~4mi), and you run five times per week, then your long run makes up 33% of your weekly mileage…

(Splitting this out into a separate topic…)

I’d be interested in opinions from those with coaching experience like @JTuori too, but in a quick look through “Daniels Running Formula, 2E,” I see a couple of comments about how the long run should be no more than 25% of your weekly mileage. Similarly, in my RRCA Coaching Certification materials, there’s a specific note about how the long run should be 25-30% of your weekly mileage.

That said, I think these percentage recommendations may break down a bit at the low end for some runners. If someone is running 100 miles per week, a 25-mile long run doesn’t seem insane. And Jack Daniels will even say things like 2.5 hours or 25% of your weekly mileage, whichever is less.

But if you’re running 20 miles or less per week, a 5-mile long run doesn’t seem quite right. I’d probably say that someone with 20 miles per week could go up to 7-8 miles for a long run, particularly if the easy runs were at least 4-5 miles. This is where the specifics of a particular person’s history and training become important.

For instance, if you’re a beginner who’s running 2 miles every weekday, taking Saturday off, and wanting to do a long run on Sunday, I’d say the long run shouldn’t be more than 4 miles for a total of 14 miles (4/14 = 28.5% of weekly mileage). However, if you’re a relatively experienced runner who’s only running two 5-mile runs during the week, you could likely do a 7-mile long run for total of 17 miles (7/17 = 41% of weekly mileage).

In theory, weekly mileage shouldn’t increase that much from week to week (no more than 10% from the previous week) so you can just look back at your previous week, or at least your recent average week, to determine it, and take the percentage from there.

Yeah I usually see this one on a case by case basis, similar to the now-debunked “10% rule”. There’s a floor and ceiling problem. Particularly in cases where someone doesn’t have a high weekly volume, you’re probably fine pushing 30-35% for the long run. It also depends a lot on running experience. Novice runners should always be more cautious and progress in a more gradual manner when it comes to individual long run and weekly volume since they’re at a higher risk of injury (body is less adapted, etc.). All in all, there’s no hard science behind it. Lydiard had runners doing long runs mainly so weekly interval sessions could be justified/get the weekly volume up.

1 Like

Thanks for this detail! Very helpful.


1 Like

Some ideas from my experience: (1) make sure the long run is SLOW, it should not be pushing the pace at all. The aim is to be on your feet and stressing the stamina for a LONG time, it is not the time to attack the hills, do fartlek etc. Of course it has to be fast enough for a normal running stride, not a shuffle; (2) adjust for cross-training when computing “mileage”, which I prefer to think of as time. So I count a 1-hr bike the same as a 1-hr run; if you want I can back compute to “mileage”. (3) Given that, I’d say the long run is 20 to 30% of the total time. (4) It may help to have a longer long run one weekend and a shorter long run on the alternate weekend. (5) Make sure to fully recover on your Monday “run” which might well be a bike or pool. (6) As usual listen to your body, especially for injury and “pancake” flatness. YMMV as always.


@D_G_Rossiter can’t agree with this enough, keep the easy runs slow. I’m partial to tracking time throughout the week as opposed to mileage anyway; your cardiovascular system doesn’t care how much distance you traveled, it cares how much time it needed to be pumping.


Agreed on keeping long runs slow, for sure, but I’m curious, is an hour of biking really equivalent to an hour of running? I find biking much easier, and have always assumed running would burn more calories due to the whole body workout. I only really have time for about 40 minutes of biking on the trainer these days, and it doesn’t feel anywhere near as hard as 40 minutes of easy running.

In researching this, I see some rules of thumb suggesting 3-4 miles of biking per 1 mile of running, but this is the only article that had any actual science behind it. I guess another question is if calories is the right measurement.

Well, my standard hour bike ride is up East Shore Drive, Burdick Hill, Cherry Lane, around the airport and by the Cornell ponds, then back downtown via Hanshaw Road. With bike cleats I can really push it, in fact I think I burn more calories than I could by running. I’ve never “biked” indoors and never intend so, so I can’t comment on that. I’d rather bike for my cardio than add “recovery” running miles. Of course that comes from advanced age, it’s impossible to run every day now.

Another opinion-

It is my understanding, as concerns the community of ultrarunners, that a long run could be as much as / should not be longer than 50% of weekly mileage. Some presumptions regarding this are a base weekly mileage of 50+/wk, (and I would not consider this if less than 40/wk for sure), and that much/most of the mileage is on trails relative to the greater variety of muscles used compared to running on roads. The logic being, say for someone preparing for a 100 mile event, a 30-40 mile long run may be desirable, or at least back-to-back 20+ mile efforts, though by no means do all 100-mile finishers train for a sustained period of time at / above 100-mile weeks.

Regardless, perhaps of greatest importance is the regular and honest checking in with how does your body feel with your training, including, but not limited to, your overall energy, waking resting heart rate comparison, muscle / joint feedback, and mental health.


Thanks for all this information and wisdom.

I gather that the recommendation is anywhere between 25% and 50%… The only non-negotiables are:

  1. The long run is slow

  2. “honest checking in with how your body feels”

Probably, new runners are less skilled at “honest checking in” so that it behoeves them to stick to the lower end of the the percentage.


1 Like