Interval training, as the name implies, is a series of repeated bouts of exercise alternated with periods of relief. Light or mild exercise usually constitutes this relief period. To understand why this method of training has been so successful, we will start with a discussion of energy production and fatigue during intermittent work.
Energy Production and Fatigue During Intermittent Work
In regards to energy production during exercise applies, of course both to work performed intermittingly and work performed continuously. However, for our purposes, there is one very important difference.
To illustrate this difference, suppose you ran continuously for as long and as hard as you could for one minute, then, on another occasion, suppose you ran intermittingly, running just as hard as you did continuously, but for only 10 seconds at a time within 30 seconds of rest between each run. If you repeated this six times, you would have performed the same amount of work at the same intensity intermittingly as you did continuously (i.e., six runs at 10 seconds each equals one minute of running), but the degree of fatigue following intermittent running would be considerably less.
The reason for this can be explained physiologically. The answer lies in the different interaction between the phosphagen (ATP-CP) system and anaerboic glycolysis (LA system) during intermittent as compared to continuous running. Compartively, the energy supplied via anaerboic glycolysis (LA system) will be more in the intermittent runs. This means that there will be less lactic acid accumulated and thus less fatigue associated with the intermittent work. This will be true regardless of the intensity of the intermittent work bouts or how long they last.
Daryl Conant, M.Ed