Interval training involves the alternating of relatively more intense bouts of cardiovascular exercise with those that are relatively less intense. Interval training has useful applications for beginning exercisers as well as experienced and conditioned clients who wish to improve aerobic power. Fitness Trainer Pratik S Rao, Fitness First, explains what is Interval Training and how it helps boost endurance performance.

Interval training is based on the concept that more work can be performed at higher exercise intensities with the same or less fatigue than in continuous training. The theoretical metabolic profile for exercise and rest intervals stressing aerobic metabolism, fast glycolysis and the phosphagen system is based on the knowledge of which energy system predominates during exercise and during the time of substrate recovery.

It appears that every athlete needs a basic level of cardiovascular endurance, which can be achieved using a wide variety of training modalities and programs. The traditional modality has been slow, long distance run. For the strength and power athlete, however, this may be irrelevant or even detrimental to power development. Adequate gains in aerobic fitness can be accomplished with Interval training when appropriate and needed. The old concept of an ‘aerobic base’ for purposes of recovery in anaerobic sports is somewhat misunderstood: athletes can gain aerobic training adaptations without the use of long distance running because a variety of alternative training programs exist (e.g., Interval training with short rest periods). 

Some of these adaptations include

• Reduced body fat
• Increased maximal oxygen uptake
• Increased respiratory capacity
• Lower blood lactate concentrations
• Increased mitochondrial
• Capillary densities and improved enzyme activity.

There are generally considered to be two basic types of Interval training

1. Aerobic
2. Anaerobic.

For either, the following four variables may be considered when designing an IT program:

• Intensity of the work interval (e.g., speed)
• Duration of the work interval (e.g., distance or time)
• Duration of rest/recovery interval

Number of repetitions or repeat intervals
Aerobic IT is best suited for those beginning in the poor or low cardiorespiratory fitness classifications because it is less intense. Anaerobic IT is primarily reserved for those in the higher cardiorespiratory fitness classifications who desire to increase speed, lactate threshold and overall aerobic power.

Interval Training Recommendations

Rest to Work Ratio

The longer the interval, the shorter the rest as a percentage of the interval. In other words, short intervals with a high muscular demand will require longer rests when viewed as a percentage of the interval. Fifteen second intervals will need at least a 2:1 rest to work ration.
Three to one will work better for beginners.

Interval rest recommendations are as follows:

• 15 seconds. Beginners at least 45 seconds (3:1), more advanced 30 seconds (2:1)
• 30 seconds. Rest one minute to one minute 30 seconds (3:1 or 2:1)
• 1 minute. Rest one to two minutes (2:1 or 1:1)

Just remember, as the intervals get longer, the recovery time does not need to be as long as it relates to the interval. In other words, a two minute interval may only need to be followed by a two minute rest.

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