A Full Squat is defined as a squat in which the pelvis goes below the level of the knees. The ROM of this exercise does not go further and from the parallel position (ie in which the thighs are parallel to the ground) you return to the starting position.
This type of squat is generally used in the world of power lifting where the "lift" is considered good only if the ROM condition described above is satisfied.
The execution of a full squat "adapts" to the ROM of the movement: the starting position should in fact allow a movement such as to exploit the stretch reflex (the stretch reflex) at the point of maximum elongation.
Being able to take advantage of this reflex makes it easier to overcome the critical point of movement by exploiting the elastic energy expressed by a muscle when it is stretched.
The critical point of a squat is not in fact the lowest point but the transition between the return from this position and the thrust of the quadriceps.
Indicatively, this point occurs when the knee is around 80-90 degrees of flexion.
The limiting factor of the weight used (in terms of force curve) is this sticking point and being stronger at this point means significantly increasing the weight used.
The starting position of a full squat, power lifting style, is as follows:
Place your feet wider than your pelvis. This allows you to keep the legs (part of the body between the knee and the ankle) more vertical.
More vertical legs raise the point that the pelvis must reach and therefore reduce the range of motion.
The feet must be extra rotated on subjective criteria, indicatively the greater the stance and the more straight the feet must be (to reduce the mobility of the hips).
The pelvis must be flexed and then tilted forward. the flexed pelvis allows to “pre-stretch” the buttocks and hamstrings in order to generate a stretch reflex earlier and therefore exploit this elastic force to explode in the position of maximum elongation.
The back must be sloped to keep the bar in line with the center of the foot. The pelvis must necessarily move backwards because otherwise if it were to tilt without going backwards, the center of gravity would be outside the center of pressure (the center of the foot).
The pelvis therefore moves backwards and to maintain neutral alignment throughout the spine, the back must also be tilted.
The barbell can be positioned or in the high bar position, i.e. resting on the upper part of the shoulders just below the upper trapezius, or in a low bar position, or with the barbell positioned at the height of the posterior deltoids.
This choice is very personal and depends on individual mobility levels. If you have good extra shoulder rotation, wrist mobility, strong elbows and good hip mobility then you can opt for the low bar.
This allows a greater recruitment of the muscles of the posterior kinetic chain and also allows to keep the knees further higher by tilting the trunk more.
Raising the knees further allows for a further reduction in ROM and ultimately the use of heavier weights. The high bar position is more natural (for most people).
The elbows should always be kept in line with the trunk. To do this you need to extra rotate your shoulders. The extent to which the bar must be challenged is subjective.
The barbell must be pulled against your back (upper trapezius or posterior deltoid). This allows to contract the great dorsal muscle and ultimately it is possible to have greater stability throughout the spine and a better connection between motor muscles (pelvis and thighs) and the support base of the weight (shoulders).
From this position contract the transverse abdominis and flex the knees and keep the weight on the center of the foot (this forces the pelvis to flex as much as necessary).
The feet must constantly push into the floor and the extra knees rotated. When you feel the stretch reflex contract the quadriceps and bring the barbell upwards imagining to bring the trunk upwards (this allows you to recruit the hip extension only as needed).
All the mistakes of a full squat are attributed to a lack of strength, mobility and mastery of the technique. In general choose always weights of which you have full mastery and choose a squat technique based on current mobility and focus on correct execution.
The full squat is a very technical and individual exercise and therefore you must feel free to vary the execution based on the signals that your body sends.
A point of debate is the Valsava maneuver (take a deep breath and hold the air), this should only be used for maximum repetitions and not chosen as part of the technique.
The whole body is involved when this exercise is performed correctly. the muscles of the trunk act as stabilizers while those of the lower part (pelvis and thighs) are the protagonists of the movement.