Michael Boyle's Strengthcoach.com Blog

There are two primary methods of performing interval training. The first is the conventional Work to Rest method. The Work to Rest method uses a set time for work and a set time for rest. Ratios are determined and, the athlete or client rests for generally one, two or three times the length of the work interval before repeating the next bout. The big drawback to the work to rest method is that time is arbitrary. We have no idea what is actually happening inside the body, we simply guess. In fact for many years we have always guessed, as we had no other “measuring stick”.

Heartrate Method

With the mass production of low cost heartrate monitors, we are no longer required to guess. The future of interval training lies with accurate, low cost heartrate monitors. With a heartrate monitor there is no more guessing. We are no longer looking at time as a measure of recovery, as we formerly did in our rest to work ratios, we are looking at physiology. What is important to understand is that heartrate and intensity are closely related. Although heartrate is not a direct and flawless measure of either intensity or recovery status, it is far better than simply choosing a time interval to rest. To use the heartarte method, simply choose an appropriate recovery heartrate. In our case we use sixty percent of theoretical max heartrate using the Karvonen method (see The Problem With Formulas box). After a work interval of a predetermined time is completed the recovery is simply set by the time it takes to return to the recovery heartrate. When using HR response, the whole picture changes. Initial recovery in well-conditioned athletes and clients is often rapid and shorter. In fact rest to work ratios may be less than 1-1 in the initial few intervals. An example of a typical workout for a well-conditioned athlete or client is show below.

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