You run a few times a week, your 5K or 10K keeps getting easier, but your time has stalled. That's often the moment interval training makes the difference. This guide covers what an interval workout is, how it differs from a tempo run, which workouts fit your level, and how fast to run them.
01What is interval training?
In interval training, you alternate faster segments with easy recovery. Because you get a short break in between, you can spend more time at a high pace than you could in one continuous run. You'll also find a short definition in running terms explained.
For the 5K and 10K, the focus is on repeats of about 1 to 5 minutes at a pace close to your 5K race pace. These workouts challenge your VO₂max, your ability to hold a fast pace, and your feel for race pace.
The benefit is well researched. In a meta-analysis of 28 studies in healthy adults, both continuous endurance training and interval training produced large gains in VO₂max, with possibly a small extra gain for interval training. Another analysis found that interval training with longer repeats, 4 minutes or more, improved time-trial performance slightly more than short sprint intervals. A follow-up analysis saw the biggest gains in people who were less trained to begin with. So intervals don't replace easy running. They add to it.
Can't run 30 minutes or a 5K without stopping yet? Then you don't need intervals. Build your base first, for example with the 5K training plan. Speed comes after that.
02 · Interval, tempo, and thresholdInterval, tempo, and threshold: what's the difference?
At RunCulture, we work with Jack Daniels' training zones. Your current fitness is captured in one number, your VDOT, and your paces follow from it. You can read how these zones fit together in zones and quality (VDOT). For the 5K and 10K, these workouts matter most:
| Workout | How it feels | Typical format | Pace for a 25:00 5K |
|---|---|---|---|
| Easy run (E) | You can hold a normal conversation | 30 to 60 minutes continuous | 6:10–6:55 min / km9:55–11:05 min / mi |
| Threshold or tempo run (T) | Comfortably hard, talking in short sentences | 20 minutes continuous or 3 × 8 minutes | 5:20 min / km8:35 min / mi |
| 10K pace | Firm, your race pace | 4 × 4 minutes or 3 × 8 minutes | 5:10 min / km8:20 min / mi |
| 5K pace | Hard, your race pace | 5 × 2 to 5 × 4 minutes | 5:00 min / km8:05 min / mi |
| Interval (I) | Hard, clearly out of breath after 2 minutes | 5 × 3 to 6 × 5 minutes | 4:55 min / km7:55 min / mi |
| Repetitions (R) | Fast and smooth, short segments | 8 × 45 seconds to 10 × 1 minute | 4:30 min / km7:15 min / mi |
The paces in the last column are an example for one runner: someone who currently runs a 5K in 25 minutes, which works out to a VDOT of about 38. They come from the same table as our VDOT calculator, rounded to 5 seconds. If you're faster or slower, all your paces shift with you.
A tempo or threshold run is longer and a little less hard. It trains you to hold a firm pace for a long time. For threshold segments, Daniels uses short breaks, about 1 minute for every 5 minutes of running. In everyday running talk, a tempo run usually means this kind of threshold workout; running terms explained has more on it.
An interval workout is harder, at roughly the pace you could hold for 10 to 12 minutes. Daniels prefers repeats of 3 to 5 minutes, because it takes about 2 minutes for your oxygen uptake to reach its peak. Shorter repeats work too, as long as the recovery stays short.
Repetitions (R) are short, fast segments of no more than about 2 minutes, with generous recovery. They train your speed and a smooth, efficient stride. The goal is to run fast without straining, not to wear yourself out.
03 · 5K versus 10KWhat the 5K and 10K ask of you
According to Daniels, you race a 5K at about 95 to 98 percent of your VO₂max and a 10K at about 90 to 94 percent. Both distances depend mostly on your aerobic system, and both benefit from a mix of repetitions, intervals, and threshold training. The emphasis differs, though:
The closer your race, the more your workouts start to look like race pace. Earlier in your training, intervals and threshold work build your engine; in the final weeks, you mostly practice the pace you want to run on race day.
04Sample workouts by level
Every interval workout starts with 10 to 15 minutes of easy running, with a few short strides if you like. Then come the repeats, and you finish with 5 to 10 minutes of easy jogging. Running warm-up and cool-down explains how to build that routine.
The workouts below follow the progression in our personal training plans. For each level, you'll see a starting workout and, after the arrow, where you can work toward over a few weeks. Only add a rep or a minute when the previous session went well.
| Level | For the 5K | For the 10K |
|---|---|---|
| Getting started: you can run 30 minutes continuously but have never done faster workouts | After an easy run, 4 to 6 strides of 15 to 20 seconds; later 6 to 8 × 1 minute brisk with 90 seconds of easy jogging | Same as for the 5K |
| Regular runner: 3 or 4 runs a week, for a few months | 6 × 1.5 minutes at 5K pace, jog the same time → 5 × 3 minutes | 5 × 2 minutes at 10K pace, 1:45 jog → 4 × 4 minutes |
| Intermediate: 4 or 5 runs a week, some experience with faster workouts | 5 × 3 minutes at I pace, jog the same time → 6 × 4 minutes. Alternate with: 8 × 45 seconds at R pace, 2 minutes jog | 4 × 4 minutes at 10K pace, 1:45 jog → 3 × 8 minutes. Alternate with: 20 minutes continuous at threshold pace |
| Experienced: 5 or more runs a week, higher weekly mileage | 6 × 4 to 6 × 5 minutes at I pace, jogging three-quarters of that time. Alternate with: 5 × 4 minutes at 5K pace or 10 × 1 minute at R pace | 3 × 8 minutes at 10K pace, 1:45 jog. Alternate with: 6 × 4 minutes at I pace or 25 minutes continuous at threshold pace |
Daniels gives a handy upper limit for the fast part of a single interval session: no more than 8 percent of your weekly mileage, up to a maximum of 10 km6.2 mi. If you run 30 km18.6 mi a week, 2.4 km1.5 mi at I pace is plenty. At a VDOT of 38, that's about 12 minutes. For repetitions at R pace, the limit is 5 percent.
If you live somewhere hilly, you can do some of your intervals uphill, for example 8 × 1 minute hard up a slope with an easy jog back down. On a hill, effort matters, not the pace on your watch.
05How often per week?
For most runners, one interval session a week is enough. Run the rest of your week easy. Well-trained endurance athletes do roughly four out of five sessions at an easy intensity, and in RunCulture's training plans no more than about a fifth of your running time is fast. You can read why that balance works in polarized training.
If you're over 50, coming back from an injury, or sleeping poorly, one faster workout a week is plenty. If your reps feel harder each week instead of easier, take an easier week.
06Recovery between reps
The recovery between your reps is part of the workout. Too short, and you start the next rep tired and therefore too slow. Too long, and your body cools down so much that you have to get going all over again.
Jog very easily during recovery, or walk if you're just starting out. Standing still is fine, but the next rep will feel harder to start. Don't use your heart rate to decide when to go again: during short reps, it lags behind your effort. Heart rate zones explained covers why.
07 · Setting your paceSetting your pace with the VDOT calculator
The right interval pace is your pace now, not the pace of the time you hope to run. Here's how to find it:
08 · Common mistakesCommon interval training mistakes
A flat stretch without intersections or traffic lights makes intervals much easier. The route planner shows an elevation profile for every route, so you can find a quiet, flat loop for your reps.
09 · Your plan at RunCultureIntervals in your personal plan
If you'd rather not work it all out yourself, create a personal training plan. You enter your distance, your race date, and a recent time, and the plan sets your paces from your current fitness, just like the VDOT calculator.
Prefer a fixed plan? See the 5K training plan or the 10K training plan. They focus mainly on finishing the distance; for a faster time, a personal plan is a better fit. For more ways to get faster, such as hill training and strength training, see how to improve running speed.
