One of my fondest memories of running was going to train at the local grass football pitch as a young boy. The coach would have us run a series of quick runs, as fast as we could, along the lengths of the pitch, and then we had to run slow on the widths.
At the time, I was unaware that in doing so, we were using the recognized running technique known as interval training.
Interval running involves periods of high-intensity running alternated with low-intensity running, walking, or rest.
Far from those football pitches in Ireland, interval training was and still is being used by the world’s elite runners, proven in various studies to be a key contributing factor to their incredible race performances.
If you’ve reached a plateau and are not seeing any improvements in your running times, then interval training may just be what you need to reach your next PB.
Let’s dive in and take a closer look at this testified technique. In this article, we’ll walk you through the benefits, how best to implement interval training, the usual recovery periods, and some sample interval running sessions.
Ready? Let’s get into it.
4 benefits of interval training
Designed in the 1930s by German coach Waldemar Gerschler and physiologist Hans Reindell, it was only in the 1952 Olympic games when Czech athlete, Emil Zatopek, attributed his 3 gold medals to interval training that the benefits of this method became recognized.
If performed consistently and correctly, interval training can provide strong physiological and mental benefits.
However, if you are new to this type of training, it is essential that you ease yourself into it as can put a lot of stress on the body.
Related Article: Marathon Interval Training
#1: Increase in aerobic capacity
One of the main benefits of interval training is an increase in aerobic capacity.
The most widely used term in sports science when referring to an athlete’s aerobic capacity is VO2 max. It is defined as the maximum rate of oxygen consumption during incremental exercise and is an indication of how efficiently an individual uses oxygen while exercising.
When coupled with continuous steady running, interval training can give you a real boost in cardiovascular fitness.
Your heart will become stronger and more efficient leading to an increase in your maximum stroke volume and cardiac output. Thus, in short, interval training will allow you to increase the amount of blood that you can pump per beat.
Other research associated with interval training points to a reduction in the risk of heart disease and high blood pressure.
#2: Increase in anaerobic capacity
As we have learned, the body’s ability to supply the muscles continuously with adequate levels of oxygen is a key determinant in their performance.
However, a common limiting factor in an athlete’s ability to improve is often due to an underdeveloped anaerobic capacity.
By training at paces quicker than those associated with your aerobic capacity, you’ll improve your body’s ability to delay the onset of lactic acid and better handle the effects that it produces.
To do this in a controlled manner and to be able to apply a careful approach, it is important to know your paces.
Related: Marathon Pace Guide: How To Determine It + Race Pace Strategy and Running Pace Calculator.
During the 1960s, Frank Horwill, the highly accomplished British endurance coach, studied work carried out by the Nobel Prize-winning physiologist, A.V.Hill, and later devised a system whereby he was able to define the aerobic to anaerobic ratio of common running paces.
Related: Aerobic vs Anaerobic Training: Why You Need Both in Your Running Plan
He indicated that aerobic running ranges from jogging (100% aerobic) to 3km speed (60% aerobic). Similarly, anaerobic running starts with 200m (95% anaerobic) and extends to 1,500m speed (50% anaerobic).
For example, running at speeds quicker than 1500m pace is considered more anaerobic than aerobic. For instance, running at 800m is considered 67% anaerobic and 400m pace 83% anaerobic, whereas 3km pace is considered 60:40 aerobic to anaerobic.
The table below provides a summary of the aerobic to anaerobic ratio of the common running paces.
| Pace | Aerobic (%) | Anaerobic (%) | Category |
| Jogging | 100 | 0 | Aerobic |
| Half marathon | 94 | 6 | Aerobic |
| 10km | 90 | 10 | Aerobic |
| 5km | 80 | 20 | Aerobic |
| 3km | 60 | 40 | Aerobic |
| 1500m | 50 | 50 | Aerobic |
| 800m | 33 | 67 | Anaerobic |
| 400m | 17 | 83 | Anaerobic |
| 200m | 5 | 95 | Anaerobic |
#3: Adds variety to your training plan
If all your training involves steady continuous running, you may feel that it has become a little monotonous.
By adding some interval running sessions into your weekly schedule, it should give you a new lease of life, increasing motivation and improving your performance.
Plus, studies show that short bursts of intense movement and exercise stimulate a greater release of feel-good endorphins such as serotonin and dopamine, meaning interval training can also make your training more enjoyable.
Start by replacing one of your normal steady runs with an interval training session and allow your body to gradually adapt to the new stimuli placed on it.
Related: Want To Get Faster? Here’s Why More Slow Runs and Less Speed Work Is The Answer
#4: Efficient for those time-poor runners
Multiple studies compare intense interval running with moderate continuous running, and each shows that within the same period of training time, far greater improvements are achieved by interval running.
This makes interval training a great option for those who find it difficult to fit in their training around other life and work commitments.
The first man to run under 4 minutes in the mile, Roger Bannister, used interval training effectively in the 1950s when he squeezed in his session of 10 x 400m repeats during his lunch breaks from his arduous and time-consuming medical studies.
That said, it is important not to overload your body by turning all your training runs into time-efficient interval sessions. They are there to be a compliment to your steady aerobic running that should always make up most of your weekly training.
As Frank Horwill notes: “The world’s leading work physiologists agree that only about one-third of the total weekly training distance should be devoted to working between 80 and 100 percent of VO2 max”
How to incorporate interval training into your Runs
People who are not used to interval running commonly get overly excited and start way too fast in their first interval training sessions, meaning that they often have to quit in the middle of a workout due to exhaustion.
It is vital to incorporate intervals into your training routine gradually. I’d recommend you start by replacing one of your normal steady runs with an interval session and build up slowly from there.
Related: How to Run Without Getting Tired: 11 Ways To Boost Your Running
Remember that running at higher intensities and speeds, you’ll be putting your body more stress. To minimize the overall burden or stress on the body, you should always consider the following points:
- By adjusting the duration of the interval, intensity, and recovery periods
- By wisely selecting the total number of intervals
Related Article: The Ultimate Guide to Recovery Runs
It is important to note here that the quicker the pace, then the longer the recovery you’ll need to be able to maintain the required times for each interval. Running at a 10km pace for a 5-minute interval feels very different from running an 800m pace over a 45-second interval.
Imagine that you have a target of running 20 minutes for the 5k distance. This would equate to a 4.00 minutes/km pace that you’ll need to be able to sustain over the whole distance.
Start with intervals at your target race pace – 5km pace. This could be 6 x 800m in 3.12 (as 5k pace is 96 seconds per 400m) and take a 2 min recovery between intervals.
Then you could try running at a speed quicker than race distance, 3k pace for instance.
The 3k is 3.50 minutes/km (6.08 minutes/mile) or 92 seconds per 400m. A good initial session is to run 8-12 repetitions of 400m in 92 seconds with a 92-second recovery.
Then the next stage in your speed adaptation is to run intervals at a target 1500m pace of 88 seconds per 400m (3.40 minutes/km or 5.52 minutes/mile).
Here, you should aim to run 6-10 repetitions of 400m with a 90-second recovery. If this is too difficult, reduce the interval to 200m and run it 10-12 times with the same recovery.
How much rest should I take between intervals?
One of the biggest mistakes people make with interval training is choosing the wrong intensity or not taking enough time to recover between intervals.
New runners should start with aerobic intervals with a work-to-rest ratio of 1:2.
As you get more comfortable with interval training you could then apply the usually recommended ratios of 1:0.5-1 for the slower aerobic paces and 1:2-2.5 for the fast anaerobic paces (see table 1).
For example, if you are starting with intervals in the aerobic range, then you’ll be able to take a recovery that is around 50% of the duration of the interval.
For instance, if you were performing 5 intervals of 1500m @ 10k pace, then you could take 3 minutes recovery. Then as you get fitter, you can reduce the recovery gradually, but still focus on maintaining the pace.
However, if you have a session of very fast anaerobic intervals, then you’ll have to take a much longer recovery than the duration of the interval. For instance, if running 8 x 200m @ 800m pace in 44 seconds, then you would be advised to take a 2-minute recovery.
Remember, the switch from aerobic to anaerobic will require you to engage your fast-twitch fibers more, so ensure you complete a comprehensive warm-up and include some fast strides before commencing the session.
Final thoughts
Remember that running intervals at higher intensities (see anaerobic range from Table 1) you’ll be putting your body under a lot of stress, so don’t forget to always do a comprehensive warm-up that includes some fast strides before starting any interval sessions.
The key is to run at the appropriate pace so that you can recover and still complete the rest of your weekly training sessions without too much fatigue.
A final recommendation is to concentrate on your own pace and don’t turn these interval sessions into races. This is common in a group training setting, so it is essential to stick to your own desired effort.
And with that, good luck!
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