If you’re following a Runna training plan, you’ll likely see interval runs appear each week. These are some of the most important sessions in your training, designed to improve your speed, efficiency, and confidence at faster paces.
For many runners, interval workouts can feel intimidating at first. But once you understand how they work and why they’re included in your plan, they quickly become one of the most rewarding sessions of the week. They're demanding, but they're worth their weight in gold for their benefits to your fitness.
Let’s break down what interval training is, how hard you should be running, and why these sessions play such an important role in helping you become a stronger runner.
What Is Interval Training?
Interval training is a structured workout where you alternate between short, faster running efforts (i.e., the intervals) and recovery periods.
💡 A simple interval session might look something like this:
Warm-up
6 × 400m fast efforts
90 seconds recovery between each rep
Cool-down
The faster sections are designed to push you above your normal comfortable running pace, while the recovery periods allow you to partially recover before the next effort.
Because the faster efforts are broken into manageable chunks, you can spend time running at speeds that would otherwise be difficult to sustain continuously.
Over time, this helps your body adapt to running faster.
Why Interval Training Matters
Interval sessions are one of the most effective ways to improve your running performance. By regularly running short efforts at faster speeds, you train both your body and your mind to handle higher intensities.
We often say running is as much a mental game it is a physical one, and intervals are a great opportunity to develop the mental fortitude to keep going when things get tough.
Some of the key benefits include:
Improved running speed: intervals help you become comfortable running faster than your usual training pace.
Higher VO₂ max: these sessions challenge your cardiovascular system, improving your ability to deliver oxygen to your muscles. Read more about VO₂ max and its role in running in our full guide here.
Better running efficiency: faster running encourages better mechanics and stride efficiency.
Improved pacing awareness: learning to repeat consistent efforts teaches you how to control your pace, this is an invaluable skill on race day!
Mental resilience: intervals push you outside your comfort zone, helping you build confidence and mental strength even when the target is daunting at first.
How Hard Should Interval Runs Feel?
Compared to tempo runs, which sit at a “comfortably hard” effort, intervals push into a harder intensity zone.
While intervals are often the most challenging sessions in your plan, lean into it! Use this as an opportunity to mentally prepare to push yourself, and know that it's only for controlled distances. You’re only running at this effort for short periods at a time, with recovery breaks in between.
A useful way to judge effort is the Rate of Perceived Exertion (RPE) scale, which measures how hard a run feels from 1–10.
Most interval reps in your Runna plan will fall around RPE 8–9.
This should feel:
Relative effort is hard but controllable
Breathing is heavy
Talking is difficult
You’re focused on maintaining form and pace
You should be able to achieve the targets by applying the above
You should feel challenged, but not completely sprinting from the start. In fact, we really discourage you from going out too fast! We're aiming for targets you can do again and again.
The goal is consistent, repeatable efforts, not an all-out sprint that leaves you unable to finish the session. Let's dive into approaching pacing intervals the right way.
How to Pace an Interval Session
One of the most common mistakes runners make with intervals is starting too fast. Start as you mean to go on, with strong effort but one you can hold onto!
Aim to:
Ease into the first couple of reps: use the first one or two intervals to settle into the target effort.
Run consistent efforts: each rep should feel similar in difficulty. Ideally, your final rep is just as strong as your first.
Manage your recovery: you don’t have to run during recovery, walking or jogging is fine! Focus on slowing your breathing and composing yourself for the next rep.
Try to stay upright and keep moving, rather than stopping completely, which helps your body recover more effectively.
What Are Taper Intervals?
Toward the end of your training plan, you'll see some taper interval sessions.
These workouts include shorter, sharper efforts designed to keep your legs feeling fast without adding too much fatigue.
During a taper interval session:
The reps are usually shorter
The total volume is lower
The focus is on maintaining speed and dial in the rhythm of your cadence
These workouts help you arrive at race day feeling fresh, confident, and ready to run fast.
Final Thoughts
Interval sessions may feel challenging, but they’re one of the most powerful tools in your training.
They help you:
Run faster
Build endurance at higher speeds
Improve pacing and confidence
Remember: consistency matters more than perfection (as usual!). Focus on running controlled efforts, staying relaxed, and trusting the structure of your plan.
Over time, you’ll likely find that the paces that once felt difficult begin to feel much more manageable, and that’s a great sign your training is paying off. Happy running!