Interval Training 101

Helping you decide what pace and what distance your intervals should be

Today, I’m going to be writing about interval running: what pace you should run your intervals at and how long those repeats should last. If at the end of this post, you still have questions or something doesn’t quite make sense, you can find me on Facebook or my website.


For this article to make sense in terms of terminology being used, I’d like to get some vocabulary out in the open so we all have similar terms to work with.

When I talk about training paces, I primarily focus on 4 different paces that are widely observed and used: Tempo Pace, Threshold Pace, Interval Pace, and Race Pace. Below, I’ll break down what each pace should feel like, should be in relation to a race pace (ie: half marathon pace; note: not the same as Race Pace”), and how much rest is typically taken after each rep.



Feel like: “Comfortably hard effort”

Similar Race Pace: 10k – half marathon – 1-hour race pace

Rest after: Since tempo runs are continuous, there typically isn’t any rest

4 typical running paces: tempo, threshold, interval & race pace
The 4 most typical running paces


Feel like: “Comfortably hard effort

Similar Race Pace: 10k – half marathon

Rest after: Typically 1 minute for every 5 minutes of work


Feel like: hard effort, but not all out

Similar Race Pace: 5k – 8k

Rest after: Same amount of recovery as the repeat (in time)


Feel like: Fast in nature and short in length

Similar Race Pace: 800 – 3k

Rest after: Same distance as the repeat. Example: 4×200 with 200 jog

Pacing Strategy

In my coaching (and running) experience, it’s optimal for us to adapt and grow as runners when we hit every training zone roughly every 7 to 14 days. What this means is that in any given 2 to 3-week stretch, we should be looking to touch on each of the 4 training zones mentioned above.

This might look something like this:

Sample 2 Week Training Block
Sample 2 Week Training Block

What this means is simple: to keep progressing with your running, it’s key to hit some volume of running at each of the respective running paces within that 1 to 3-week window. Keep in mind that training for a 5k has a different emphasis on speed while the marathon has more of an emphasis on endurance. There is quite a bit of overlap in both (long runs, threshold repeats, tempo runs, etc) but they come from different ends of the spectrum.

How to Pick the Right Pace

To be honest, there are a number of strategies I use to determine what pace I should do my runs at. How you decide may differ and that’s totally fine!

Running Paces & Distances
Finding the right volume and speed for workouts

Personally, I use 3 primary sources for determining what pace my athletes should be running. I use McMillan’s pace calculator, TinMan’s Running Calculator, and Jack Daniel’s vDOT charts. Each brings a unique perspective to what their paces should be for workouts.

If you need more than just the charts, Jack Daniels has a great book that most coaches swear by.

To narrow down the specific pace of a workout for a runner I coach, I think about these factors:

  • recent race results
  • current fitness
  • weather conditions (summer/winter)
  • where in their racing season they are

After I consider the above factors, I then use a calculator to determine the pace they should be running. After their pace is set, I focus on how long they should be running at that pace for. That brings me to the distance. See below.


There is no single formula, key, or guideline that says what your repetition distance should be. Some runners can only handle repeats lasting less than 400 meters. Other more experienced runners, may see great gains in fitness if they do repeats lasting upwards of 20 minutes. Knowing where you fit on the ever-moving platform is how you’ll see the biggest bang for your buck.

Running Paces & Distances
Effective pacing strategies for distance runners

Below, I’ll outline the positives and negatives of both short reps and longer reps.

Short Reps

Benefits of short reps:

Short repetitions are good for runners who need a mental break or physical break. A newer runner may benefit from repeats lasting 1 minute in length. On the other hand, an experienced runner may run 400s as their shortest repetition but they might do 16 of them at threshold with a really short break. The short rep gives the runner a chance to regroup, refocus their attention and have a tangible goal to attain: 1 minute of work at a time.

Setbacks of short reps:

For a runner to see fitness gains, the work to rest ratio should remain at 5:1 for a threshold effort. So for example, is a runner only runs for 2 minutes at threshold pace, the rest should be no more than 20-:25 seconds. Because the repetition is short, the rest needs to be equally as short. It becomes a lot of starting and stopping and that could become irritating. A secondary setback to shorter reps is that to achieve the same level of stimulus, a lot more reps need to be done – to do the same amount of work as, say, 5 x 1 mile, the runner would potentially have to run upwards of 20-30 reps. That becomes tedious to count and not something I would prescribe to a runner I coach.

Key terms for distance runners to know, use, and master
The key concepts and terms for distance running

Long Reps

Benefits of long reps:

An experienced runner can see a jump in fitness if they are able to sustain an effort for a longer period of time. If Runner A runs a 25 minute sustained effort at tempo pace and Runner B runs 25 minutes at tempo pace but broken into 5 x 5 minutes, Runner A is spending a significant amount of time at their tempo pace (without breaks) and that will provide a bigger fitness increase even though they are both spending 25 minutes at their respective tempo paces.

deciding on pace and distance
How to decide what pace and how far to run each interval

Setbacks of longer reps:

As I shared earlier, there are very valid reasons and fitness benefits for doing the 5 x 5 minutes, including the potential for slowing down and loss of proper running mechanics, but overall, it’s my belief that if a runner can do 25 minutes straight at tempo pace it’s (marginally) better than that same effort broken up into smaller segments.


What makes creating a training plan difficult isn’t determining what pace you should run on what day of the week, but also in deciding the correct volume (amount of work) and how it’ll be broken down into repetitions. As a coach, it’s my job to find the right balance of speed and distance, package it into something that is achievable and moderately challenging and provides my runners with the opportunity to grow as an athlete.

If you still have questions or you’d like me to create a training plan for you, you can go directly to my contact page to reach me!


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Dr. Jack Daniels VDOT & USATF Certified Running Coach
Dr. Jack Daniels VDOT & USATF Certified Running Coach

I am a USATF Track and Field & Dr. Jack Daniels VDOT O2 certified running coach. I have more than 19 years of experience running and more than 10 years of experience coaching runners. Click for more information!

Disclosure: There also may be affiliate links present – which means if you buy something with that link, I make a small commission.

17 thoughts on “Interval Training 101

  1. This is a great explanation of different types of paces. Thanks for sharing


  2. I always been kind of intimidated by interval training. Thanks for giving so much information on the different types of paces. This is going to be very helpful to me!


  3. This is a great post with really great tips. I think a lot of people have trouble determining with their pace should be with intervals – all the factors you listed really do come into play when you’re trying to figure it out!


  4. This is a super handy guide to speed training. I don’t do as much as I used to, usually one tempo run a week, plus some hill work, but I really could use a little more variety.


  5. Janelle @ Run With No Regrets October 10, 2018 — 11:44 AM

    This was so helpful, thank you for the thorough explanation! I have to admit I was confused on the difference between intervals and tempo runs. I have found that short reps are a lot more fun to do, but I felt like I improved so much more once I started doing 1-mile repeats in my marathon training!


  6. I’m glad it helped! Tempo is sustained, intervals are repeats (run, recover, repeat). I agree – short reps are good for the mental aspect. As long as you keep the rest proportionally short, you’re getting the same stimulus


  7. Variety is good! You could always break up your tempo run into smaller segments. The pace is very close to each other and the difference may spark some fitness gains you were missing from doing similar run paces week after week.


  8. Yep, there are so many variables. I like using the calculators as they are good predictors


  9. Not at all! Intervals don’t have to be FAST at all. The word interval really just means running with breaks.


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