The “perfect” distribution of training intensities is a rather intriguing topic when it comes to physical preparation. Determining what is perfect is in itself a mission impossible and a reasonable approach might instead be to consider what successful athletes do.

As a matter of facts, this is exactly what researchers did (link), reporting the training characteristics of successful athletes winning international medals. The results of those scientific observations are that successful endurance athletes generally spend about 80 percent of their training times at a relatively low intensity (perceived as “easy”) and the majority of the remaining 20 percent is often spent at very high intensity (perceived as “hard”), with relatively little amount of time spent at medium or moderate intensities.

Professor Stephen Seiler is the physiologist who popularised the term “polarised training” to define the training distribution described above: 80% at low intensity and 20% at high intensity (link). More recently Matt Fitzgerald, a well-known endurance sport author, wrote the book “80/20 Running” based on the polarized training concept. When it comes to the actual training process, there are different ways to track intensity distribution and, as written in a previous piece, different way to understand and assess exercise intensity. For the purpose of achieving a polarised distribution of training intensities, training zones based on heart rate and perception of efforts are both valid ways to guide endurance training.

From a practical point of view, it’s interesting to note that most recreational cyclists (and athletes in general) make the mistake to train too hard, too often… resulting in too much time spent at medium intensity, compromising the quality workouts.

As such, a common recommendation is to “go slow to go fast”. Enjoy!