We are aerobic beings by nature, however in order to perform physical work at greater intensities, we lean on our anaerobic energy systems to maximize our potential.
The Intensity Continuum explores our ability to transition between Aerobic and Anaerobic states to match the energy demands of a specific task. We divide the Intensity Continuum into High Intensity and Sub-threshold Intensity.
The point at which we become anaerobic dominant is our threshold and is primarily dependent on the condition of the individual. Threshold can be determined in a variety of ways, whether it’s Lactate Threshold, Critical Power or Maximum Lactate Steady State (MLSS) or even more simple, at a Rate of Perceived Exertion (RPE) 8 or above on a 1-10 scale (10 being maximal effort). You can also use % of max heart rate where the average individual becomes anaerobic around 75% and above but keep in mind the threshold will change the better condition the individual is in (elite endurance athletes can stay aerobic as high as 90% of HRmax). You have the freedom to use whichever measurement best suits your practice.
In summary, Sub-threshold is Aerobic Conditioning and High Intensity is Anaerobic Conditioning.