We start from the assumption that the Zone Training method, often confused with the 21-stroke technique, with stage repetitions or with partial repetitions, is a training method in itself, which is based on very specific assumptions.
Conceived in the late 1970s by Brian Johnston, it is based on the concept of breaking down the complete ROM of an exercise into several parts (2 or 3, depending on the width of the ROM itself), in order to maximize muscle load. in every part of the ROM (range of motion) in fact.
It starts from the biomechanically most unfavorable part of the ROM (more difficult to be clear), and then continues in the easier one after the programmed repetitions; in this way the second part of the exercise, the theoretically easier (favorable) one, will no longer be such, obtaining a greater muscular load compared to a full ROM execution.
To give a practical example, look at the photo in which I am performing a seated dumbbell curl: the biomechanically most unfavorable part is the one in which starting from the initial position (arms fully extended) the forearms are flexed until reaching an angle of 90 ° with the humerus.
Specifically, the dumbbell or barbell curl is a classic example of "inter-pivoted lever", or first kind of lever, which can be disadvantageous, neutral or advantageous, but I do not intend to bore the reader with biomechanical dissertations, maybe we will face said topic in a separate article.
The result pursued in an exercise in "Zone Training" is to create a greater involvement, and consequent damage, of the muscle fibers in a smaller number of sets, this is achieved precisely because of the aforementioned maximization of the muscle load in each area of the ROM.
The "Zone Training" method, precisely because of the assumptions on which it is based, goes well with the HIT (or Heavy Duty) methodology. From here the so-called "hybridized" training protocols were developed, which, while still based on reduced work volumes to the advantage of intensity, combine the "intensity" techniques of HIT with those of Zone Training.
Therefore we speak of hybrid because it is neither a pure HIT protocol, nor a zone training one, but a training program that takes parts from both. It will then be up to the technician to dilute the training contents (training zone combined with pre-anchoring series, stripping or rest pause, etc.) in the structuring of the work program, based on individual needs and not least on the training seniority of the person, trying to minimize systemic stress (planning adequate frequency, volume of work and periods of discharge) and to maximize adaptive responses.
Over the last decade I have been able to develop a small statistical study of my own on a sample of about 400 people who I trained with these methodologies, finding significant gains in muscle mass and strength, vascularity and density; obviously we are talking about natural athletes, that is who do not take any chemical help, therefore having to deal with the whims of cortisol and the physiological times necessary for the compensatory and supercompensatory processes (to be clear, both the work and the cycling of intensity and discharge periods must be meticulously planned, active and or passive).
Last but not least it will be of fundamental importance (but this regardless of any method you follow) to choose the exercises to be performed based on personal biomechanics, I always remember that exercise X does not necessarily mean work Y on anyone, kinetic chains are sometimes capricious and anarchic (allow me the joke), and their work can be altered by an unbalanced posture, which is often the result of our experience, but this is another story.
I invite you to read my articles on the net and on the My-personaltrainer.it portal (link at the bottom of the page).