You have a long run on your schedule this weekend and you’re staring at your GPS watch wondering: is there actually a right pace for this, or do I just run?
Most runners treat the long run like a distance goal and let effort sort itself out.
The research says that is leaving real adaptation on the table, and in some cases, actively working against the work you put in.
Run too slow and the aerobic stimulus drops below the threshold needed to drive adaptation.
Run too fast and you arrive at your next quality session under-recovered, blunting the work you just put in.
So, in this article you’re going to learn the research-backed practical advice on:
- the exact effort zone in seconds per mile shown by research to maximize capillary density, myoglobin, and mitochondrial development
- how to calculate your personal easy long run pace from your current 5K time
- why the specific pace range matters and what happens to your adaptation when you drift outside it
What is the purpose of your long run
The first step to determining long run pace is assessing the purpose and intensity of your long run session.
Not all long runs are created equal.
Some long runs are designed to simulate marathon conditions or teach you how to finish fast.
These sessions are hard workouts, with extra recovery days built into your plan after each one.
Other long runs are designed to be easy, building aerobic endurance and putting time on your feet.
These sessions are not recovery runs, but they are not hard workouts either.
If your training schedule is well-written, it should be relatively clear what the intensity or goal of the long run is. Understanding the purpose and desired outcome of your long run is important because long runs are just one piece to the training puzzle.
For example, race specific long runs are an integral part of a training plan and can help take your running to the next level. However, if your long run is designed to be a relatively easy day and you run too hard, you’ll start your next workout too fatigued and risk poor performance and injury.
Your hard long runs already have predefined paces built into your training plan.
The harder question is what pace to target on your easy long runs.
What is the optimal pace if your long run is easy?
If your long run is easy – not a specific workout, then what is the optimal pace? To answer that question, examining the physiological benefits shows how pace shapes each adaptation:
Capillary development
Capillaries are the smallest of the body’s blood vessels and they help deliver oxygen and nutrients to the muscle tissues. The greater the number of capillaries you have surrounding each muscle fiber, the faster you can shuttle oxygen and carbohydrate into your muscles.
Capillary development appears to peak at between 60 and 75 percent of 5k pace.
Running much faster or slower than this range produces diminishing returns on capillary development.
Increase myoglobin content of muscle fibers
Myoglobin is a protein in your muscle fibers that binds and stores oxygen.
When oxygen becomes limited during exercise, myoglobin releases that stored oxygen directly to the mitochondria.
The more myoglobin in your slow-twitch fibers, the more oxygen your muscles can access at race pace.
While all muscle fibers contain myoglobin, the ones we’re most concerned with targeting during the long run are the Type-I (slow twitch) muscles. Research has shown that maximum stimulation of Type I muscle fiber occurs at about 63-77 percent of VO2max. 63-77 percent of VO2max is about 55-75 percent of 5k pace.
Increasing Glycogen storage in the muscles
Glycogen is how the body stores carbohydrates in the muscles for usable energy. While this isn’t important for races that last under 90 minutes, when racing the marathon, the more glycogen you can store in your muscles, the longer you can prevent the dreaded bonk.
The goal with easy long runs is to deplete the muscles of their stored glycogen. The body responds to this stimulus by learning to store more glycogen to prevent future depletion.
The faster you run the greater the percentage of your energy will come from carbohydrates. While there isn’t any scientific research on the optimal pace that burns significant carbohydrate while still providing enough energy to get through a long run, experience and the study of elite runners has shown that a pace of about 65-75 percent of 5k pace is optimal.
Mitochondria development
Mitochondria are organelles in your muscle cells that convert carbohydrate, fat, and protein into usable energy.
The more mitochondria you have, and the higher their density, the more energy you can produce during a run.
Two researchers, Holloszy (1967) and Dudley (1982) established the benchmark research on optimal pace for mitochondrial development.
Holloszy found that maximum mitochondrial development occurred at about 2 hours of running at 50 to 75 percent of VO2max.
Dudley confirmed the best strategy for slow-twitch mitochondria enhancement was running for 90 minutes per outing at 70 to 75 percent of VO2max.
How Do You Calculate Your Long Run Pace?
To target your easy long run pace, take your current 5K race pace and add 60 to 90 seconds per mile.
Research has shown that easy long run pace corresponds to 65 to 75 percent of maximum heart rate for most runners.
The simplest field check is the conversational test: if you can speak in full sentences without gasping, you are in the right zone.
If you are laboring to finish a sentence, your pace is already too fast.
For a specific number, use your current 5K race time and the chart below to find your easy range.
Newer runners need an even larger gap, closer to 90 to 120 seconds per mile slower than 5K pace.
Their aerobic base is still developing, so effort spikes faster at higher intensities.
| 5K Time | 5K Pace | Easy Long Run Range (min/mi) | Easy Long Run Range (min/km) |
|---|---|---|---|
| 18:00 | 5:47/mi · 3:36/km | 7:00–8:00/mi | 4:21–4:58/km |
| 20:00 | 6:26/mi · 4:00/km | 7:45–8:45/mi | 4:49–5:26/km |
| 24:00 | 7:43/mi · 4:47/km | 9:00–10:15/mi | 5:35–6:22/km |
| 28:00 | 9:00/mi · 5:35/km | 10:15–11:45/mi | 6:22–7:18/km |
| 32:00 | 10:18/mi · 6:23/km | 11:30–13:00/mi | 7:09–8:04/km |
| 36:00 | 11:36/mi · 7:12/km | 12:45–14:30/mi | 7:55–9:00/km |
These ranges reflect the 65 to 75 percent effort threshold that maximizes capillary density, myoglobin, and mitochondrial density.
Staying within this zone also limits the muscle damage that would compromise your next quality session.
Running at the slower end of your easy range produces nearly identical aerobic adaptations to the faster end, with meaningfully better recovery for your next workout.
If you are returning from a break or building your base for the first time, target the slower half of the range.
Stay there for the first 2 to 3 weeks before moving up.
Summing it all up
That’s a lot of research, percentages and numbers. If you’re not as analytically inclined as I pretend to be, here is a neat chart to sum up the research:
The body of evidence is clear, your optimal long run pace is between 55 and 75 percent of your 5k pace, with the average pace being about 65 percent.
It’s also evident from this research that running faster than 75% of your 5k pace on your long run doesn’t provide a lot of additional physiological benefit. Therefore, pushing the pace beyond 75% of 5k pace only serves to make you more tired and hamper recovery.
In fact, the research indicates that it would be just as advantageous to run slower as it would be to run faster. 50-55 percent of 5k pace is pretty easy, but the research clearly demonstrates that it still provides near optimal physiological benefits.
If you’re feeling tired and the long run isn’t scheduled to be a hard day, don’t be afraid to slow your long run down. My suggestion is to start on the slower side of the pace recommendations (50% of 5k pace) and slowly pick it up through the run if you feel good.
Consider this research when debating the pace of your next long run and make it count.
RunnersConnect Bonus
Download your FREE Long Run and Aerobic Pacing Calculator now.
Need help converting your race times to your optimal easy and long run pace? Download our FREE calculator and we’ll do the math for you.
15 Responses
Hello RunnersConnect/Jeff,
Thanks for the email newsletter you send out. I enjoy reading them.
I have been a runner for 31 years – I started when I was 16.
Most of my professional career has been spent in the physical preparation (or training/coaching) people in running based sports. i also worked for 4 years as a sport scientist.
With an ever-growing (45) group of recreational runners it is always a challenge, as coach, balancing the many pieces that comprise and individual training plan and then the phases sand sessions to support meeting the objectives of the plan. Science and art both play a role.
Speed or pace (not always the same as intensity) of different sessions – or parts of sessions – to meet given objectives is often a discussion point. And, “easy” pace doesn’t necessarily equate with easy effort after 90+minutes. For this reason I tend to use “slow-ish” of thereabouts.
That said, as you mention, the ‘pace’ of long runs os often dependent upon their purpose (or objective/s). Sometimes the ‘purpose’ is equally psychological and emotional (eg. confidence, self-efficacy, self-esteem), or even social, as well as physiological (and musculoskeletal).
I read your ‘optimal pace for the long run’ article with interest. It is insightful and well written. Although the studies from 1967 and 1982 are well dated that isn’t to say they can’t be of value.
Based upon your recommendations, I’d like to highlight two things:
1) 5km races are more often than not run at 95-100% VO2max. This being the case, the “percent of 5km” guidelines you give are significant underestimates. they should nearly be identical to the “percent VO2max” column. Just a thought.
2) to run at a pace 50% of my VO2max speed is to run at half the speed. If I run 5km in 20mins that is 4mins/km. Half/50%* this speed is 8mins/km. This is ridiculously slow, and isn’t much quicker than a fast walk (9-10mins/km). Even if you meant add 50% to your 5km pace this would only be 6mins/km, and for someone who can run 20min/5km that is certainly a very easy pace (I’d still suggest too slow for long-easy runs)
[62.5%= 7mins/km; 75%= 6mins/km]. Are you certain about these?
Well done again on your blogs/emails overall, and thanks for providing me with the opportunity to write to you.
Paul Ford
Hi Paul,
Thanks or the comment and sharing your questions. I too tend to use slower paces when assigning easy paces. In my opinion, easy means easy, so the coal is to just run easy; however, the number one question I receive is “what is my easy pace”. That’s why I wrote this article.
You’re right about the date of the studies, but there just hasn’t been anything that’s looked at these aerobic development factors in runners recently. I don’t think the physiology has changed, so I still think they are accurate.
To answer your questions.
1) I think the 5k to VO2 max paces are pretty close – within that 5% difference. You have to remember to that beginners will usually run a 5k at closer to 90% of Vo2max because they don’t have the skills and training to push themselves. This article is aimed more to beginners. Most experienced runners don’t need to be told what “easy” is.
2) You’re making a mistake with your calculation. 50% doesn’t mean half of 5k pace. It means literally, 50% of/slower than 5k pace. In your example of a runner with a 5k pace of 4:00, 50% of 4:00 is 6:00 pace. I think you’ll find that isn’t that slow for a recovery type run. Plus, 50% is the very low end of the aerobic development. On average, it seems 65% seems to be the number that hits all four systems. As such, you’re looking at 5:20 pace or so.
Hope that makes sense and thanks for reading!
Hi Jeff, I was also confused by your use of percentages when explaining paces.
When people use percentages and they say “[x] should be [y]% OF [z]”, it means x = z * y%, not x = z * (1+y%) as you meant in your article.
To get the meaning of the percentages that you intended, you should write that your training pace should be [y]% SLOWER THAN your 5k pace, not [y]% OF your 5k pace.
Sorry for the confusion. I updated a post to include a calculator. Enjoy!
Ooops, (2) should read, “to run at a pace 50% of my 5km speed is to run at half the speed”…
PF
Dear Coach Jeff:
I saw what happened at this year’s Marathon. I am sedentary by nature, but want to begin training in the hopes of qualifying for the 2015 race. Once I begin, I hope to set up a website to track my progress and encourage others like me to show the runners and victims of yesterday’s tragedy that their loss did not go unnoticed and in fact is inspiring positive life changes in others!
How is it best to begin?
This may seem a emotional response, but I am committed. Former military, but out for a hip expanding decade. Just need a reasonable restart since the information on effective exercise has changed a lot.
Thank you,
Lisa
Hi Lisa,
That’s a great way to celebrate the lives of those lost. To get started, I would find a good plan and make sure you stick to it. You may have to start with some run/walk, but if you’re able to take it one day at a time, you’ll get there. We have some great basic training plans that would help guide you if you need. Best of luck on your journey!
Hi Coach Jeff.
Thank you for the article.
I am having difficulties in calculating the paces. Please check my work below
20min 5k is 6.4 min/mile 6:24 in mm:ss notation.
To find 50%: 1-0.5 = 0.5; 1+0.5 = 1.5; 6.4*1.5 = 9.6; 9:36 mm:ss agrees closely with your 9:40.
To find 75%: 1-0.75 = 0.25; 1+0.25 = 1.25; 6.4*1.25 = 8.00; 8:00 mm:ss agrees with your 8:00.
To find 55%: 1-0.55 = 0.45; 1+0.45 = 1.45; 6.4*1.45 = 9.28; 9:17 mm:ss agrees closely with your 9:20.
To find 65%: 1-0.65 = 0.35; 1+0.35 = 1.35; 6.4*1.35 = 8.64; 8:38 mm:ss agrees closely with your 8:40.
Is this the correct interpretation?
Many thanks Jeff,
Peter
Yup, you’ve got it right.
Interesting article. It would be wonderful if you could provide the sources you used to develop that handy-dandy chart.
Thanks!
Quick Question from a beginner: how long does the effect of a correct long run pace remain? For instance, do the capillaries keep developing over a period of time with say, weekly long runs or do they come back to their pre run shape after a day or a few hours of the end of the long run.
Jeff, I’m 39 and started running about 2 years ago and I’ve completed your Sub 3:30 marathon program twice now (finishing my first full in 3:34ish and the second in 3:40 (very hilly run “The Flying Monkey” , Nashville TN)). I typically only miss a couple workouts a month (due to work, etc.)
The work outs are awesome and I love the speed training segments but I’m wanting to get in to the 3:10 – 3:15 range. What else can I do to run a 7-minute mile for 26.2 miles?
Id signup for our upcoming marathon training webinar: https://runnersconnect.net/marathon-training-webinar-signup/. That will give you a lot of great info about what you’re likely doing wrong and how to fix
Thanks for the explanation and the calculator.
To plug in the number on the calculator, do we just run a 5K (for example) as fast as we can?
Hi Joe, yes, if you do not have a recent 5k race to compare to, it would be good to see where you are at before using this guide, or you can use a previous 5k, and just be prepared to adjust slightly.