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Continuous and interval training - update

Brian Mackenzie reviews the pros and cons of interval and continuous training.

Continuous training is when an athlete exercises in a steady aerobic way and interval training is characterised by repetitions of work with a recovery period following each repetition. Continuous training can be broken down into the following sub-divisions, which have slightly different effects upon the energy pathways:

  • Running at 50 to 60% of maximum heart rate or 20 to 36% of V02 Max. Very easy pace, it metabolises fat and is aerobic. Duration 60 minutes plus. Useful for joggers & ultra-distance runners
  • Running at 60 to 70% of maximum heart rate or 36 to 52% of V02 Max. Slightly faster pace, it burns glycogen and fat and is aerobic. Duration 45 to 90 minutes. Useful for marathon runners. Improves cardiovascular system and capillarisation
  • Running at 70 to 80% of maximum heart rate or 52 to 68% of V02 Max, 10km pace, it burns glycogen and is aerobic. Duration 30 to 45 minutes. Useful for 10km and marathon runners. Improves cardiovascular system, capillarisation and is glycogen burning
  • Running at 80 to 90% of maximum heart rate or 68 to 83% of V02 Max. 5km pace, it burns glycogen and is anaerobic. Duration 10 to 20 minutes. Useful for 5km to marathon runners. Improves cardiovascular system, capillarisation, glycogen burning, lactate tolerance and removal
  • Running at 90 to 100% of maximum heart rate or 83 to 99% of V02 Max. 800/1500m pace, it burns glycogen and is anaerobic. Duration 1 to 5 minutes. Useful for 800 to 5km runners. Improves glycogen burning, lactate tolerance and removal

Interval Training

Interval running enables the athlete to improve the workload by interspersing heavy bouts of fast running with recovery periods of slower jogging. The athlete runs hard over any distance up to 1k and then has a period of easy jogging.

During the run, lactic acid is produced, and a state of oxygen debt is reached. During the interval (recovery), the heart and lungs are still stimulated as they try to pay back the debt by supplying oxygen to help break down the lactates.

The stresses put upon the body cause an adaptation including capillarisation, strengthening of the heart muscles, improved oxygen uptake and improved buffers to lactates. All this leads to improved performance, in particular within the cardiovascular system.

Before undertaking interval training, a few simple rules should be understood:

  • Undertake a period of continuous running before starting Interval running
  • Consider the various elements of the session and ensure that they are within the scope of the athlete
    • The length of the work interval, longer gives a better effect
    • The pace should be comfortable raising the athlete's heart rate to the required % of HRmax(see above)
    • The number of repetitions should reflect the condition and age of the athlete
    • The rest interval should enable the athlete to jog and bring the heart rate down to near 100 to 110 bpm
  • Improvements can be made by altering any of the above variables. However, the coach should only change one variable at a time
  • All changes should be gradual and take place over someime
  • Ensure the surface to be run on is flat and even. It is usual to do interval training on a track although it can be done on a good quality grass playing fields. Roads are not a suitable surface because of the pounding effect

Circuit training is a standard method of interval training.

The benefits of interval training

In planning training programs, controversy still exists as to the optimum duration of the workloads needed to gain maximum results. It would seem a waste of effort to train for longer periods than necessary for the same gain in fitness. In an attempt to address this problem, a research project in Thunder Bay, Ontario, Canada, randomly assigned 21 females, aged between 18 and 26, into two groups before embarking on a seven-week training programme.

The subjects were tested in a laboratory to evaluate their maximum oxygen uptake (VO2 max), ventilatory and lactate thresholds, all key indicators of aerobic fitness. All the subjects trained at 85% of VO2 max for the first two weeks, with a 5% increase every fortnight. Thus, they trained at 85% for the first fortnight, 90% for the second fortnight and 95% for the third. The frequency of training, which continued to exhaustion, was four times each week. Group one trained with 30-second interval workloads, while group two used a two-minute workload. Both groups, however, continued with work to recovery ratio of 1:1.

At the end of the seven-week training programme, the subjects were retested in the laboratory. It was discovered that there was a significant increase in VO2 max, ventilatory threshold and lactate thresholds of all subjects. There was, however, no significant difference between the two groups utilising the different workload durations.

This might suggest that there is little difference in using 30-second or two-minute duration workloads, while both forms of workout have strong training effects for aerobic fitness.

The study does not, however, state the initial fitness levels of the subjects, which has an effect upon the possible gains in fitness achievable. Further, the training does not mimic a realistic training programme, where utilisation of different energy pathways should be involved, including the important steady-state component of training.

Article Reference

This article first appeared in:

  • MACKENZIE, B. (2004) Continuous and interval training - update. Brian Mackenzie's Successful Coaching, (ISSN 1745-7513/ 16 / October), p. 3-4

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • MACKENZIE, B. (2004) Continuous and interval training - update [WWW] Available from: [Accessed

About the Author

Brian Mackenzie is a British Athletics level 4 performance coach and a coach tutor/assessor. He has been coaching sprint, middle distance and combined event athletes for the past 30+ years and has 45+ years' experience as an endurance athlete.