This section includes

  • General introduction
  • Measuring intensity
  • VO max training
  • Purpose
  • Intensity level
  • Anaerobic capacity training
  • Purpose
  • Intensity level
  • Recoveries
  • Purpose
  • Intensity level
  • Examples of interval training

General introduction

Also known as repetition training, interval training involves alternating periods of fast running with periods of recovery. The fast sections are intense and the recoveries are light. It is performed at various intensity levels, but anaerobic capacity and VO2 max intervals are the most important for distance runners. As with all interval training, you’ll get the most out of your session by maximising the time spent at the appropriate intensity. Therefore, your recovery periods should be sufficiently long to facilitate this, but not so long that your heart rate falls so low that the beginning of the next fast section is spent below the optimum intensity. (When you start an interval, it may take some time for your oxygen consumption and heart rate to reach the optimum level.). Intervals should become more and more race-specific as your training programme progresses.

Measuring intensity

The intensity of your workouts can be assessed in a number of ways …

… heart rate – most club runners have a sports watch that can be used to measure heart rate. Generally speaking, heart rate increases in a linear fashion with increasing effort, making it a good measure of exercise intensity. A somewhat crude measure of maximum heart rate (MHR) is [220 – your age] but this can be as much as +/- 20 bpm from the average. A better way of determining your MHR is to warm up thoroughly and then run hard up a moderate hill of about 500m, jog back down and go again twice more. If you run them flat out, you’ll be very close to your maximum heart rate by the end of the third repeat. It is generally accepted that you cannot increase your MHR with training, as this is genetically determined.

… % of heart rate reserve (HRR)

HRR = Maximum heart rate (MHR) – Resting heart rate (RHR)

Your HRR is more accurate than basic heart rate, but requires more calculation. Your RHR is best measured before you get out of bed in the morning and an average taken over a few days.

… rate of perceived effort (RPE) – a subjective assessment of how you feel during the workout. Some use a 5 point scale, others a 10 (see table below).

… pace – different workouts can be run at different paces, such as your 5k, 10k or half marathon pace etc.

Your heart rate can be affected by fatigue, heat, and terrain, among other things. So it is best to use at least two of these indicators.

A typical RPE/Pace scale
RPE Description Pace %Maximum heart rate*
0 No effort Standing still
1 Very easy Walking
2 Easy Easy pace 70-81
3 Moderate Marathon/half marathon pace 74-84
4 Somewhat hard Lactate threshold/10k pace 80-91
5 Hard 5k/10k pace
6 Harder 5k pace 90-94
7 Very hard 3k pace
8 very, very hard 1500m/1 mile pace
9 Extremely hard 800m pace
10 Maximal effort Sprinting/final push at end of race 100
*Take as a guide only - calculate your own MHR if you can

The fitter you are, the more intensely you can exercise at a lower rate of perceived exertion, which is one good reason for recording your RPE after each workout, then you can have some measure of your progress.

This chart shows the effect that differing levels of intensity can have on your body:

% Heart Rate Reserve Outcome
50-60% Aids recovery and improves overall health
60-70% Develops endurance and promotes fat burning
70-80% Increases aerobic fitness
80-90% Improves anaerobic capacity
90-100% Develops speed and increases maximum performance

VO 2 max training


Improves the heart’s ability to pump a high volume of blood, and the muscles ability to extract more oxygen from the blood.

Improves speed over 5 and 10k distances, and helps marathoners who are slower over short distances and/or who may be plateauing at their marathon pace. (Marathon runners who are fast 5 and 10k runners would be better off with lactate threshold training).

Intensity level:

Lower than anaerobic capacity interval training, higher than lactate threshold, i.e. between harder and very hard (RPE 6-7).

Long fast sections with relatively short recovery periods that are somewhere between equal or half the duration of the fast sections.

If you’re training for a marathon, you should do a VO2 max session every two weeks in the ‘support phase’ and end them when entering the final, ‘race-specific phase’. Though some authors suggest the benefits can be so great that they should be carried out more regularly throughout the training programme. What it comes down to is that if you continue to improve, then keep doing these sessions and once the improvement stops, simply maintain your fitness by doing a session every few weeks.

Anaerobic capacity training


The high level of effort involved improves speed over shorter distances, so benefits 5 and 10k runners the most. For half- and full-marathoners, flat out hill reps may be more beneficial.

Intensity level:

This type of interval training should be performed at such an intensity to produce very high levels of lactate in the muscles. Therefore, short, fast sections are interspersed with recovery periods that are 2-4 times longer than the fast sections, thus giving your body a chance to clear the lactate before going again.

Fast sections should be performed at RPE8-9 (extremely hard), such that your heart rate reaches close to maximum. Allow your heart rate to fall to around 100 before going again, so you can repeat the fast sections at the same speed and intensity.

Do 10-30 second reps once a week during the ‘base building phase’, but, as with VO2 max training, end it when starting the ‘race-specific phase’.



To allow you to complete your workout at the intended pace. If your recovery jogs are too short, subsequent efforts will be slower than the optimum pace or you may end up cutting the workout short. If your recovery is too long, your heart rate and oxygen consumption will decrease so much that it will take longer to reach the optimum pace in the next interval.

Intensity level:

Between intervals resist the temptation to stand bent over with your hands on your knees. Active recoveries are better than passive ones, so keep on the move – walk if necessary, but try to break into a jog as soon as possible.

The benefits of keeping moving during recovery are:

  • Increased clearance of lactate from your muscles and blood
  • Helping your muscles to stay warm and loose
  • Keeping your heart rate and oxygen consumption somewhat elevated so less time is required to reach the optimum level during the next interval.

Examples of Interval Training

Speed intervals – generally relatively short intervals run at faster than 5k pace. You may like to progress from short, fast intervals to longer and slower ones.

Ladder intervals – a series of intervals of increasing distance and slower pace, or conversely, decreasing distance and increasing pace.


 6 minute, 5 minute, 4 minute, 3 minute, 2 minute, 1 minute, with 1 minute of active recovery between each, with a progressively faster pace such as 10k pace to 1500m pace.


1 minute, 2 minute, 3 minute, 2 minute, 1 minute at 1500m to 5k pace with active recoveries of equal duration following each interval – i.e. shortest intervals fastest, longer ones slowest.

Lactate Threshold/Cruise intervals – breaking up a tempo run into several intervals. These intervals are run between LT pace and 10 seconds faster than LT pace. (For more information see the article on Lactate Threshold Training).


LT Intervals Recovery jog
4 x 6 mins 2 mins
3 x 8 mins 3 mins
20 mins, 16 mins 4 mins
16 mins, 12 mins, 8 mins 4 mins

Lamptervals – is one of our own training sessions – here you run fast between sets of lampposts with recovery jogs between them. If you can find a long stretch of evenly spaced lampposts then (a) you won’t need to look at your watch or (b) measure out a specific distance. Any long estate road (such as Badgers Way) should be good for this. For an even more demanding workout, do this along Page Hill Avenue – using lampposts up a hill!

Use an athletics track – the benefits are obvious in that distances are easily measured and the surface is nice and flat, enabling you to focus solely on speed. Apart from the ideas mentioned above, you can run hard out for, say, 20 seconds, take a rest, then run hard back with the goal of reaching your starting point within the 20 second period. Then go again for 30, 40, 50, 60 seconds.

Effective speed workouts on the track
5-8 laps of stride straights , jog turns @ pace you can hold for 1 minute
2 sets of 4 laps of stride straights, jog turns/4 min jog between sets @ pace you can hold for 1 minute
2 sets of 5 x 150m/250m recovery jog between intervals/4 min jog between sets @800mpace
2 sets of 5 x 200m/200m recovery jog between intervals/4 min jog between sets @1500m/1 mile pace
2 sets of 4 x 300m/300m recovery jog between intervals/4 min jog between sets @1500m/1 mile pace

% Heart Rate Reserve Outcome
50-60% Aids recovery and improves overall health
60-70% Develops endurance and promotes fat burning
70-80% Increases aerobic fitness
80-90% Improves anaerobic capacity
90-100% Develops speed and increases maximum performance