The Long Run – How Long is Long Enough?

long run

This week, we welcome back Andy DuBois for some more insights into how ultra runners should train for those big races. The long run is a very personal thing, and as ultra runners, we tend to be of the belief that we need to be doing really long runs for our 100km+ ultras. But do we really need to do that? Is it practical? In this article, Andy offers some vital tips and rationale as to what you might want to consider for your weekend long runs. Once again, we’d like to thank Andy for his contribution to the website, so take it away mate!

long run
Andy on his way to a sub-30hr UTMB

The long run is obviously the most important training session of the week for an ultra runner but how long should it be?

I was initially of the opinion that longer was better but after building up to a long run of 75km before my first ultra and dying big time in the race I re-evaluated my ideas.

For my second race my longest run was only 45k and it was run at a much slower pace than my previous long runs. This was a resounding success as I was still running strong with 95 miles of running in my legs.

Why the big difference and why did running less ks at a slower speed in long training runs result in me running more ks at a faster speed during the race?

Whilst you may read about some of the pro’s putting in 8 hour training days on a regular basis the majority of us haven’t got the time to do this or the bodies that could handle that kind of training so we need to be a bit smarter about how we go about it. The often quoted rule when training for marathon is if you can do 30-35k in training then you can do 42k come race day. Using the same percentages for an ultra would have you running 70+k run for a 100k race or a 120k+ for a 100mile race. Clearly not a realistic goal.

So what is the ideal distance?

Unfortunately there is no best answer for this as it depends on a number of variables including the amount of ascent descent covered in the run, the speed you run at, the terrain you run on, what your body can handle, the recovery time necessary after a long run and the amount of training you have done for the rest of the week. Manipulating these variables to discover the optimum long run distance for you is more art than science but there are several guidelines you can apply.

1. Recovery Time

The longer the run the more recovery time you’ll need. There is a point of diminishing returns where the longer your run the more days recovery you will need. This obviously impacts training for that week. If you need any more than a day’s rest before you can run again then I feel your long run is too long (or you are running it too fast)

2. Intensity

A common mistake for runners making the jump from marathons to ultras is to continue to run their long runs at the same pace. This is fine if you are training for a 50k but if you are training for 100k or more than you need to slow down. Your long run should feel easier than the long runs you did training for a marathon. Running your long run faster is not necessarily better. The aim of the long run is to build endurance by improving the body’s ability to burn fat, increase capillary density and mitochondria in the muscles. The faster you run the less fat you burn so the less stimulus there is to improve your fat burning ability. the faster you run the more damage you will do to your muscles which can affect the rest of the weeks training.

long run
How intense should it be?

3. Terrain

Your long run should be done on similar terrain to your race. You can’t expect to cope with running 100k with 5000m of ascent descent if your long runs are 40k and covering 500 m elevation change. A good aim is to work at increasing the elevation change per km to the same as expected in the race. Ie if the race has 5000m in 100k then that’s 500m per 10k. You should aim to gradually increase the elevation change so that you get to approx 1500-2000m for 30-40km.

You can also use this principle based on time rather than distance. Ie If you are hoping to run 100k with 5000m of elevation change in 20 hours then that’s 250 metres per hour so a 4 hour run should have at least 1000m of ascent descent.

If your race is on technical trails then it makes sense that your long run isn’t done on road or gentle fire tracks and vice versa – train specifically for the course.

5. Back to back or single long run?

Running back to back suits many runners better than a single long run. Covering 50-70km in 24 hours is a lot less stressful on the body than covering the same distance in 12 hours. So for example running 25-35k on Friday afternoon followed by 25-35k Saturday morning would place less stress on the body than running 50-70k non stop on Saturday.

The one proviso for this is that you don’t run any harder just because you are doing only 25-35 compared to 60. When you set out Friday afternoon tell yourself you are running 60k and adjust your pace accordingly. When you stop after 25-30k you should feel comfortable and not be exhausted.

Another way to use back to backs is to do a shorter but higher intensity run the day before the long run to get you used to running long on already fatigued legs.

6. Walking in your Long Run

Too many runners think that walking is a sign of weakness , after all if you are a runner isn’t walking cheating? However in an ultra – particularly a trail ultra almost everyone walks some of it. So you may as well practise it. Walking in your long run also allows you to cover more mileage with less risk of injury . For example running 40km non stop will put a lot more load on your legs compared to running 50k but broken up into a 5k run 1k walk. For more info on how to improving your walking during an ultra have a look here.

7. The really long run

Once or twice before your main race I think it’s worth spending a weekend getting one or two long days on your feet. Before all the successful 100milers I have done I have spent a weekend around 4-5 weeks before the race covering 120-160km in a period of 2-3 days. As I compete in trail races this is all done in trails and includes a fair bit of walking. I have found that although I generally need 2-3 days off after this the benefits gained outweigh the lost days training. The pace for these should be very very easy and the goal is more to spend 8+ hours on your feet for a couple of days rather than trying to run a certain pace. It’s also a great chance to test out your nutrition strategy and race gear. Depending on what your weekly mileage is and how long your long run is will govern how much you run and how much you walk.

8. Injury Prevention

Always remember the more you run in a fatigued state the more susceptible to injuries you will be. The length of your run should always be moderated by what your body can handle and what it can recover from. Keep in mind that some injuries such as tendon injuries are cumulative so whilst you may feel ok after one long run, a month later you are in pain. Progress slowly and always err on the side of caution.

long run
Staying clear of injury is a big consideration when you’re training for a miler

So why did a much shorter run at a slower pace give me far greater training benefit than a longer run?

That 45k run was run over 6 hours and included well over 2500m of ascent and descent. It was preceded by a 30k run the night before which also included nothing but hill reps. I recovered well enough from this to hit the track two days later and clock up some respectable 1 mile repeats (sub 5.30). Previously the long run built up to a point that I would need at least 3 days to recover from. Being able to back up from long runs and run at speed a few days later made a massive difference to my endurance at the back-end of a 100 mile race.

That’s not to say this is the best option for you. This worked for me when I was training for UTMB with the massive amount of ascent and descent but for less hilly 100 mile races I have trained differently.

By considering all the variables and listening to your body you should be able to find the optimal distance for your long run.

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I'm a mediocre runner who can bat above his average when I train hard. A man of extremes, I do enjoy everything life offers and consider it an absolute pleasure just to be able to put one foot in front of the other and let my mind wander somewhere different.

8 thoughts on “The Long Run – How Long is Long Enough?

  1. I know this is a piece on “long runs”, but I think it is worthwhile to mention, if just briefly, the importance for ultra runners to include shorter, high intensity tempo/trackwork into their training rather than just slogging out lots of long runs. Personally, I’ve had more success include a few “long runs” and a lot of shorter, high intensity work in my training than when I’ve exhausted myself (and become injured) with too many long runs. For most people, you can’t train for a 100km, but you can certainly overtrain for it.

    1. too true Rachel….you cant beat speed work at the track; a 1hr track session at heart pounding levels is perfect for being able to sit at a comfortable pace in an ultra;2-3 track sessions a week.

  2. I think the length of the “long run” depends on the individual, for 100km i think 65km is fine and probably only once or twice with a back up the following day;the taper is critical….and on race day its all in the mind if you’ve done the training;lets face it ,theres always hard moments on race day and its your mind that will get you across the line or cause you to pull out.

  3. I have read about 3 days back to back run training for the 100 miler, example 15, 25, 30 Fri-Sun. Is this really necessary or the 2 day back to back will suffice? Thanks

    1. Hey Richelle. I’m a big fan of back to back runs as it really teaches you about dealing with your body on tired legs and you certainly feel the benefits I think over trying to run a really long distance in one go. I know a certain Brendan Davies here in Australia has tried this approach and worked well for him at UTMF. I also try to do back to back days for anything over 100kms.

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