Interval training is a form of exercise used by runners to improve the speed of their running. Interval training (intervals) is usually done on a running track or over a measured distance and is a combination of fast efforts followed by recoveries.

Interval Overview

An interval session involves the athlete running faster than they normally would for a period of time. After the effort part of the training, the runner is rewarded with a recovery period. During this period, the runner attempts to bring their heart rate and breathing rate down to a lower level. The most important factor of interval training is consistency. It is very likely that the person training can run fast for the first few efforts and then get slower, but it is better to keep all efforts at an even pace. The length of efforts and recovery depend upon the event being trained for, but as an example, people training for a marathon may run a session of eight 1000-metre efforts with a two-minute recovery, whereas a 1500-metre runner may do a much faster session of 12 times 200 metres with a 100-metre jog recovery.

Why Do Intervals?

The physiological changes to an athlete's body are beyond the scope of this entry. In brief, pushing the body past the 'comfortable' speed of running increases aerobic capacity, trains the fast twitch muscles to operate at a higher/faster level and makes the athlete more tolerant of lactic acid build up. The result of interval training is that a runner who can comfortably run at eight-minute/mile pace and runs their intervals at a seven-minute/mile pace will be able to increase their steady comfortable pace under an eight-minute/mile pace.

Interval Sessions

Interval sessions come in numerous formats, the most popular configurations are detailed below:

Warm Up and Cool Down

These are the beginning and end of an interval session and are to prevent you doing yourself an injury by easing you in to and out of the exercise.

The warm-up is important to warm up the muscles in the body before any strenuous running (or exercise in general). An ideal warm-up session before running intervals would be ten minutes of jogging followed by gentle stretching of all major leg muscles, then a series of strides to prepare the body for effort.

The cool-down part of the workout enables the body to flush toxins such as lactic acid from the overstretched muscles. The benefit of a good cool-down is that the muscles will not be as sore the next day. A good way to cool down is to jog or walk briskly for ten minutes.

Standard Interval

The athlete runs for a set distance which is followed by a recovery of jogging a set distance or a period of inactivity for a set period of time. This effort/recovery combination is repeated until the desired number of repetitions and sets is reached.

Pyramid Sessions

The pyramid session is a variation of the standard interval session. The athlete will run ascending or descending in long intervals eg, 800 metres, 600 metres, 400 metres and 200 metres. This would comprise one set. The athlete will do numerous sets.

Parlov Sessions

An interval session run with a partner on a 400-metre track. Runner A runs 300 metres and stops. At the 300 metre point, runner B is waiting. When runner A reaches him, Runner B begins to run a 300-metre effort, at the same time, runner A is jogging 100 metres recovery in the opposite direction to which he has just run his effort. Runner A and Runner B will again meet up after runner B has run his 300-metre effort. The cycle begins again with B running the recovery leg and A running his effort. This run/jog combination is repeated between eight and 12 times.

Fartlek

Fartlek (Swedish for speed play) can best be described as an unstructured interval session which is run on the roads instead of on the track. Fartlek involves varying your running with periods of fast running followed by recovery as in a standard interval session, but a fartlek session could also include different types of terrain such as off road or even mixing in weirder efforts such as hopping or running around trees a number of times.

An example fartlek session would start with a warm-up of gentle running for ten minutes, run fast for the distance of two lamp posts and then walk/jog for the distance of two lamp posts. Because the spacing of lamp posts is not uniform, the runner will not have a fixed effort recovery period. This is why fartlek is referred to as an unstructured interval session.

Hill Intervals

A hill interval involves running up a hill for a set period of time and then jogging back down as a recovery. Repeat the desired number of times. Hill intervals provide excellent strength training for the legs along with an unparalleled cardiovascular workout.

Cautionary Note

It is unwise to enter into a strenuous exercise programme if you have not worked out for a long time. Please consult your doctor to ensure you are in no physical danger.

Glossary

• Effort - The distance or period of time of hard running.

• Recovery - The period of jogging or inactivity between efforts. Recovery can be measured in time or distance. For example, pause for one minute between intervals or jog 200 metres before launching into another effort.

• Repetitions - The number of efforts in a set.

• Set - A collection of repetitions.

• Strides - Exaggerated fast running which stretches the leg muscles in preparation for fast running.

• Syntax - An interval session is usually described in the following fashion in training manuals: 400 x 10 x 2 - 2 mins, 5 mins. This reads as a 400-metre effort with ten repetitions. There are two sets of ten with two minutes recovery between each effort and five minutes recovery between sets.