How To Structure Interval Sessions
A pick n mix for creating interval sessions. Laying out all the questions to ask so you can control as many variables as possible to create you own personal interval sessions.
What’s important when structuring intervals?
Let’s get a list going…
Interval Length - How long each interval will be.
Interval Target Pace - The pace/power you will aim to hit for each interval.
Amount of Reps - The amount of intervals you will do.
Recovery Time - How long recovery will be in between intervals.
Recovery Intensity - How easy your recovery will be between intervals.
Warm Up - How long and focussed your warm-up will be.
Cool Down - How long your cool-down will be.
Terrain - Where you do your interval session.
Other factors;
Will Interval Length Stay The Same?
Will Interval Pacing Stay The Same?
Will Rest Periods Stay The Same?
Are Intervals The Best Option?
How do you decide on the above factors?
Designing a well-structured interval session relies on knowing what you want to get out of it.
Although this can seem daunting it’s actually not too difficult. I’m sure you have a goal race in mind or an event and whether this is a 400m race or a 100 mile ultramarathon that gives you a lot of information as to what you want from your intervals.
If for example, you’re looking to improve your 5k time, that holds a lot of information to help you structure the session, just as looking to improve a 100-mile ultramarathon will give you clues too.
So let’s start answering some questions.
Interval Length;
Length of intervals is usually the best place to start as this will also influence your pace. If your target race is shorter then some short fast intervals will be good.
For example, some 3-minute reps to improve your 5k time. Or if you’re going long maybe some 10-minute repeats.
This isn’t to say that you should only do short intervals for short races or vice versa. However, it’s a good place to start as you should be able to maintain your target pace for the majority of the session.
Having interval sessions target your race pace is important and a good place to focus your efforts. You can add a variety of sessions around this to keep the training engaging and maintain motivation.
We will delve into session variety in a future post.
Interval Target Pace;
To decide on your target pace we can look at your interval length and combine that with your goal.
Let’s take my 5k goal for example. I want to do a sub 17-minute 5k which is 5:28/mi or 3:24/km so we can use this as our goal pace or even slightly quicker depending on reps and recovery. I should be able to maintain that pace for each 3-minute rep with some recovery.
Or we can look at some 10-minute reps which could be done at half marathon or marathon pace.
You may find that you can’t hit your goal pace right away as your goals may be ambitious. This is awesome! Don’t change them! We just need to work towards them. If you can’t currently hit that pace then I would take a recent result for a run you have done and try to go 10 to 20 seconds quicker for these reps. This should give you a good feel for running faster and you can build on that pace with consistency.
Amount of Reps;
We can now start to add up the reps.
If we continue our 5k example then we could look at 5 of those 3-minute reps. this would total 15 minutes of quality running with recovery in between. This is great as it’s slightly shorter than the 5k time I’m aiming for so I could even push the pace a little bit quicker than those targets.
For the 10-minute reps, we could do 4 - 6 of them. Both would be long sessions but 6 would be very long and would be something I would do as a marathon workout closer to race day* (I’ll talk a little about this further down.)
Adding and taking away reps is great as it sets your overall quality running time. This goes hand in hand with interval length. A key factor here is to make sure it’s realistic. Trying to hold 5k pace for your intervals and adding so many reps that you run for 15 minutes longer than your actual 5k time will probably be a savage and unmanageable session.
Recovery Time;
Recovery time is a fine balance. You don’t want too little or too much as both can negatively impact your session. However, we can combat this with recovery intensity when we get to that.
So, too little recovery will most likely mean your session becomes too ambitious and without sufficient recovery between reps you start to fade towards the end.
If you have too much recovery you run the risk of switching off a bit. Sometimes it’s good to stay in it and keep the focus and push hard while the muscles are warm. Too long of a recovery can go beyond that sweet spot of still feeling warm, fired up and focused.
Continuing our examples. for our 3-minute reps, a minute to 90-second recovery would suit. This is probably something I would experiment with. I would try the session with both recovery times and see which I prefer.
Now for the 10-minute reps, we can go one of two ways, either a short 2-minute 30-second recovery or a long recovery of 10 minutes.
Now I know you’re going to say “Hold on you just warned us against too much recovery” and you would be correct, however, this is where we’re going to introduce recovery intensity.
Recovery Intensity;
This I feel is often something that is dismissed or at least overlooked. Most people just smash out their reps and then stop and wait or walk for their recovery.
Often this is a good choice, especially with shorter reps as you push yourself so hard, you need that recovery to be very easy. However, don’t just stand still! Keep yourself moving, even if it’s on the spot or shaking out the muscles as it’s extremely easy to get stiff or cold and you don’t want to leap into that next rep unprepared.
Just to complete our 5k session example. For this, I would either stop and shake out my legs or slowly walk for the rest periods.
But what about long recoveries?
*Well, this is a good opportunity to look at those 10-minute recoveries for the 10-minute reps. In this scenario, I would keep running through that recovery. However, it would be at a much easier pace.
If we take my marathon pace as an example my 10-minute reps would be at 6:29/mi or 4:02/km and then my 10-minute recoveries would be at 7:15/mi or 4:30/km. Although I have an extremely long recovery, I’m keeping some intensity in there so I don’t switch off or get cold. Holding the recovery pace is still a good pace and will make the body work. Especially for such a long time and when it’s time for the reps they will really bite which is exactly what I want.
This is a very long session with 10-minute reps and recoveries! Especially if you do 6 of them, we have an hour and 50 minutes (No recovery after the last rep) before we add our warm-up and cool down.
If we’re tight on time, this is where we might introduce those 2-minute 30 recoveries. However, these would be at a much lower intensity. It would make the sessions significantly quicker and if you do a very gentle walk building into a jog through these recoveries you can create a similar stimulus.
The full session is better if aiming to nail that marathon pace but it isn’t always easy to fit in a session of this length.
Another note on recovery intensity is weather/climate. If it’s freezing, windy and chucking it down with rain you may want to up the intensity slightly from a walk to a jog in those short recoveries to stay warm. There’s no point standing around recovering if you end up frozen to the spot.
The same is true for those scorching sessions. I often find I can get shivers during a hot session from the sweat pouring off me. I prefer to try to get into the shade for my recovery and jog a little to shake this off. As counterintuitive as this seems it’s often about adapting to ensure you’re getting the best out of yourself.
Terrain;
I’ve bumped terrain up the list here as this can influence your warm-up and cool-down.
Remember ‘intervals’ is an overall term for periods of hard effort interspersed with rest/recovery periods.
This means you can do these intervals anywhere you like, whether that’s laps of the park, the road outside your house, an athletics track, on the trails, or a steep hill. Where you do these sessions will impact the session itself and the Warm-up and cool-down.
If you want to limit as many variables as possible to create the most consistent session? An athletics track is ideal. You can neutralise the wind and there is no elevation. It’s also useful for using visual distance markers rather than pacing from your watch. This can lead to a much more enjoyable session if you know that a 3-minute rep is roughly 900 meters then you can focus on that instead of staring at the pace screen on your watch. However, some may find it monotonous going around the same 400m loop.
Intervals don’t have to be on the track though. Parks work great, I often do a session in the park especially some of my longer intervals as it’s a good loop and has a little bit of hill and some turns. This can lead to a great session as you have to pick up or pull back your pace as you go up and down and this is often a much closer representation of what a course may be like on race day.
If I’m going for one of those long 10-minute on 10-minute off sessions then I just like to run and see where it takes me. The change in terrain can make the session difficult at times however, this is good for your ability to adapt to the terrain on race day. Sometimes if you’re not too familiar with a course it can be hard to pace it right when you hit an unexpected hill.
Where you do these sessions is up to you and mixing up location can keep sessions engaging. This also means you can run to and from these locations as your warm up and cool down.
Warm Up;
It’s so easy to forget about your warm-up and cool down but they’re important for a quality session. You don’t want to go straight into your first interval cold as this isn’t there for you to build into.
You want to build up the body first and then attack that initial interval with warm muscles and a focused mind.
We can use many things to do this, a nice jog building in pace over a mile or two. Then a few movements like lunges, leg swings, high knees, and heel flicks to fire up the running muscles. Finish with a couple of 15-second strides building to 75-85% max effort.
This will prime the body and mind meaning you're ready to attack interval number one straight out of the gates.
The reason terrain can affect this is you may need to get to the track, park, or hill to start your session. Getting there could be your gentle warm-up. Then a few exercises like I’ve listed above, once there you're ready for the hard work to begin.
Cool Down;
This again is another easily skipped step and although it may feel like it’s not important, it is great to flush out the legs after those hard efforts.
Putting even a tiny effort into the cool-down can set you up for another great session the next day. However, skipping this can allow some cramps and aches to creep in as everything tightens up.
I’m not saying you need a huge routine that adds bulk to your session but a 5-minute jog that tapers down to a walk followed by a couple of stretches can make the world of difference. You only need to hit calves, hamstrings and quads! A quick shake out of any shoulder tension, relax your spine and you're good to go!
From here it’s onto hydration and some well-deserved food! Session Complete!
So what about these other factors then?
The above will help you structure any simple interval session you want. Think about your goals in terms of distance and pace/time targets, then begin plotting all the variables and testing to see how your sessions come out.
However, if you want to add to the complexity and do more with your intervals then read on…
I will note here that the saying “Keep it simple stupid!” is a very good one, Especially when it comes to intervals. Adding complexity may be of value to your session however, it may also hinder your sessions.
Our bodies are very good at adapting but to create the best adaptation we need to send the body a clear stimulus. The great thing about a simple interval session is it creates a specific stimulus which our bodies respond to well.
Right, that’s the sensible bit out of the way…
Let’s dive deeper!
Will Interval Length Stay The Same?
It doesn’t have to! As much as a consistent length interval is great, you may want to stimulate the body differently.
This could mean intervals that increase in length to stretch that speed endurance. Or they may decrease to ease off or allow you to manipulate pace.
You may want to target two different energy systems during your sessions by having some short intervals followed by some longer ones.
A pyramid session might be for you, where you start with short reps and add a minute to every rep for 4 reps, before turning it on its head and dropping a minute off of every rep back to where you started. Or you can reverse this and start long before going short and then long again if you really want a tough session.
There are hundreds if not thousands of permutations to get super nerdy.
I would advise to think of the intervals in blocks. rather than just throwing them together, think about what you want from each variation of intervals and create them as their own mini-sessions which you mash together.
How you mash them together is also up to you.
You may want to do 3-minute, 2-minute, and 1-minute reps but you don’t have to do all the 3s then all the 2s followed by all the 1s. You could do a 3 then a 2 then a 1 with rest/recovery in between and then repeat that entire block 3 or 5 or as many times as you like.
You can see how quickly this can escalate and we’re still on question number 1!
Let’s look at a more complex example of a session I love for 5ks.
We begin with 5 x 400m quicker than 5k goal pace. I’m looking at around 5:15/mi or 3:16/km with a 45-second recovery. This usually feels fairly spicy but manageable.
However, we then jump straight into 2k at 5k goal pace. (currently 5:28/mi or 3:24/km for me) This is usually feeling nasty towards the last 800 meters. Those 400s quicker than goal pace come back to bite here.
Now all of that sounds lovely so what do we do to top it off?
We repeat those 400s! All 5 of them! But this time we’re aiming to go even quicker.
We stick a 3-minute recovery in here to let the body have a little respite and question our life choices before the real pain begins on these last 400s.
We want every rep to edge quicker than that 5:15/mi or 3:16/km pace! Still, off 45-second recoveries. The first 2 usually feel manageable and then rep 3 hits you like a ton of bricks! Holding on for those final 2 reps is where you get your money from this session! It’s 6k total, at or quicker than 5k pace with less recovery than you’d like!
This is a good example of an interval session with some variety that still focuses on the same stimulus.
Will Interval Pacing Stay The Same?
Well, I think I’ve answered this above, so I hope you already know the answer is yes.
There are many strategies for interval pacing and varying it can be useful. You can smash the legs with some tough efforts before putting in a longer interval to try to simulate the fatigue you would feel later on in a race.
Or you can progress the pace throughout and test that top-end pace after a long session accumulating fatigue.
One of the big benefits of manipulating pace and interval length is you can try to simulate specific racing situations that may crop up at the beginning, middle, or end of a race without having to run the race.
It’s never perfect and there is no replacement for racing but you can certainly slaughter yourself with some breakneck pace to trash legs to simulate hanging on towards the end of a half marathon PB.
Will Rest Periods Stay The Same?
There’s a theme here… Of course not! Both intensity and duration can change just like the intervals themselves.
You may want to slightly increase the recovery as you go to make sure you hit that pace. (There’s a debate to be had here whether you should pace it better, increase recovery or allow yourself to fade on the last few reps if you’re struggling to hit targets. However, I’m getting ahead of myself…)
Adding a little more rest later in the session may allow you to squeeze out that extra rep, or if you’re jogging your recoveries and the session is getting out of hand, making that recovery a walk might revive those last few reps.
Alternatively, a descending recovery time may make for a savage session that pushes you to your limits. Who knows, you may unlock a new gear by limiting that rest.
Alternating between a long and then a short rest may adapt the stimulus so you get a rep with good recovery, followed by a rep with limited recovery to push your limits.
It’s all up for manipulation and you may create a session that tests your limits in a whole new way! Remember to have fun with it and experiment. Interval sessions can be as simple or as complex as you like.
Are Intervals The Best Option?
As much as I want to say “YES!” I can’t. There is so much nuance to this, as ‘intervals’ as a term, cover such a wide range of sessions. Also, the wrong interval session may not give you what you want. In general though, if you want to get faster, there’s an interval session for that and there’s very likely to be a very specific one for your goal.
However, it may not be best to pick intervals every time! A Tempo session may be a great alternative. Now some people will give a tempo session in a structure that includes recovery between ‘Tempo’ efforts. I would argue this is just intervals with your tempo pace as a target.
For me, a Tempo session is one solid block at your Tempo pace. Now without making a left turn into a completely new topic Tempo pace is often somewhere between your Half Marathon and Marathon pace. (For me this is around 6:30/mi or 4:02/km) A Good Tempo session can be between 20 minutes and an hour. It’s a session where you’re working hard but not killing yourself! It should start to feel difficult towards the end but you shouldn’t be hanging on for dear life.
Tempo sessions are useful when training for a half or full marathon or if you want a solid session to build for an ultra. This may be a situation where an interval session isn’t what you need and the Tempo session shines.
Having said that, the 10 on 10 off session isn’t a million miles away from being an overly long Tempo run. However, referring to my above point I would still call this an Interval session.
To wrap up;
Think about your goals and what you want to achieve. This will guide your sessions.
Start with length using race goal distance as a guide.
Apply your pacing from a recent PB or race.
Add reps to accumulate a reasonable amount of time factoring in goals, ability, and time.
Decide on recovery length to keep the sessions manageable.
Set your recovery intensity to find the balance between dying and switching off.
Pick a suitable location.
Warm up and focus the mind ready for a hard session.
Cool down and shake out any niggles or tension ready for your next run
Don’t forget to have fun, work hard, and experiment!
Hydrate and smash some food! You’ve earned it!
I hope this helps you create some amazing interval sessions to push your limits in new exciting ways.
As always, please tear this post apart! I write these to understand the concepts myself as much as I do to explain them to anyone reading. Please ask questions, pick holes, and help each other strive to train harder and smarter.
I look forward to the discussion,
Bob