Interval training can be best described as bouts of exercise interspersed with short rest intervals. It is based on the concept that more work can be completed at a higher relative intensity compared to continuous-type training.
The intensity and duration of the work intervals and the length of the rest periods dictates the training response. Very short, all-out bouts of work coupled with longer rest periods are used for speed and speed endurance development.
Short, very intense work intervals with short rest periods will predominantly tax the fast glycolytic energy system. Conversely, longer, lower intensity exercise bouts and short rest intervals can be used to develop aerobic endurance.
Rest intervals are a critical component of the interval training program design. From the chart above, you can see that in order to stress the aerobic system efficiently, short rest periods are incorporated into the session. The opposite is true for speed development.
Research has shown that long rest periods (i.e. 1:12) result in low concentrations of lactic acid accumulation is low, increases in stroke volume are minimal and improvements in VO2 max are not seen. The opposite occurs when short rest intervals (i.e. 1:1 or less) are adopted (2,3).
Very short rest intervals are associated with high levels of blood lactate accumulation. This effects neuromuscular control and can negatively impact speed development. Because speed training requires maximal effort and a high quality of work, longer rest periods are more appropriate to allow the athlete to recover between work intervals. In order to enhance aerobic endurance and increase VO2max towards its upper, genetic limit, interval training should consist of 3-5 minute work bouts with a 1:1 work to rest ratio or less. The intensity should equate to 90-100% VO2max (1). This would be suitable for endurance events such as distance running, swimming, rowing or cycling for example. It could also be used for endurance development in multi-sprint sports such as rugby.
Nearly all athletes require a basic level of cardiovascular endurance, if for no other reason than recovery between intense bouts of work. Traditionally, coaches have opted for long, slow, distance training at 70-80% maximum heart rate.
The problem with this approach is that is not specific to many sports such as the multi-sprint games and can actually be detrimental to strength and power performance (4,5). Research shows that long, slow continuous training can actually decrease anaerobic / glycolytic enzyme activity (6,7,8,9,10).
For sports such as basketball, soccer, hockey, tennis, rugby and so on, interval training may be more appropriate than continuous running because it can increase aerobic power and improve cardiorespiratory endurance without the associated detrimental effects on anaerobic power.
However, its not only multi-sprint sports that can benefit from interval training. Performance in the more classical endurance-based events such as the 10k run or distance swimming can improved by incorporating higher intensity interval training even if its at the expense of some volume. Below are some sample interval training sessions.
As mentioned earlier, interval training can be incorporated into a wide variety of sport-specific training programs. While the parameters in the table above provide a suitable program guideline, drills and sessions should be made as sport-specific as possible.
Interval Training Sessions For 10-km Runners
The training sessions in the table below are designed to improve the oxidative energy system the most predominant pathway in this type of activity.
Interval Training Session For a Multi-Sprint Sport
The interval training session below is designed to improve cardiovascular endurance for a mutli-sprint sport such as soccer. Remember, that interval training describes only the format of training and is not only used for endurance development. Other sessions, using different work to rest ratios can be devised in order to develop speed or speed endurance.
Increasing Lap Run
Using the markings of a soccer pitch or similar size area, start on the touchline at the halfway point and run pace to the corner flag. Run pace diagonally to the opposite side of the pitch at the halfway point. Jog slowly along the halfway line back to the start. Continue for the other half of the pitch. This is one repetition. Repeat for 3 repetitions and rest for 2-3 minutes minutes. This is 1 set. Complete 3-5 sets in total for an interval endurance session.
Interval Training Sessions For a Tennis Player
Again, a sport like tennis requires elements of both aerobic endurance and anaerobic power. This interval training session below is designed to improve tennis-specific cardiovascular endurance.
Cross Court Drill