By Dr. Francesca Fanolla
The two most common ab exercises compared.
There are small details that often, as in all trophism exercises, "make the difference" and which, if not given due attention, risk incurring unpleasant inconveniences such as lumbar, neck pain, etc. or not achieving the set goals. for incorrect technical execution of the exercises.
The two "classic" movements that we have all tried at least once in our "sporting" life are:
1- BENDING OF THE LOWER LIMBS TOWARDS THE BUST or REVERSE CRUNCH
2- THE MUTUAL FLEXION OF THE LOWER LIMBS AND THE BUST or V-UP
But let's take a closer look ...
Lower limb flexion towards the torso or "Reverse Crunch"
In these movements, the pelvis supports the action of the legs; to concentrically contract the abdominals, the nape and shoulders must be kept on the ground. internal and on the last lumbar vertebrae, flexes the femur towards the pelvis. In order for this movement to occur only in a centripetal direction, it is necessary that the point of origin of the ileo-psoas, that is the lumbar segment, remains immobile. This is provided by the large rectus abdominis which is more involved in the second phase of the movement, that is when lifting the pelvis with a "push" upwards and towards the head (vertebral roll-up). This muscle, which originates from the last ribs and enters the pubis, comes under tension to keep the pelvis in retroversion. For further information: anatomy of the abdomen.
1 a- EXTENDED LEG VARIATION:
by placing the legs in extension and thus extending the lever arm, the exercise is much more intense and if the load is excessive for not very toned rectus abdominals, it happens that they are unable to contract concentrically and attract the pubis towards the ribs, but they are "stretched" eccentrically and move the pubis away from the ribs, bringing the pelvis into anteversion.
Then the rectus femoris comes into action which is also the flexor of the thigh on the pelvis and vice versa.
1-if the rectus abdominals are strong enough they allow the ileo-psoas to lift the femur and the rectus femoris acts synergistically with it, without an anti-release of the pelvis with consequent lumbar lordosis.
2- on the other hand, if the rectus abdominis are not trophic enough, the rectus femoris, taking on all "responsibility" for the movement, draws the pelvis towards the femur and the psoas, becoming antiversor, lifts the lumbar area off the ground with consequent lordosis.
From this we therefore deduce that the EXTENDED LEG variant is not only not recommended for beginners and in a preventive-compensatory program, but is also not very effective for the abdominals, exercising the psoas more, as also demonstrated by electromyographic studies.
1 b- VARIANT WITH BENT LEGS
With the start with the legs bent on the thighs and the thighs bent on the pelvis, the latter is brought into retroversion with consequent shortening and a state of tension in the rectus abdominis.
In all this, therefore, the psoas-iliac is able to flex the thigh on the pelvis without difficulty, indirectly favoring the retroversion action of the pelvis of the rectus abdominis.
This starting variant with bent legs therefore allows:
- not to contract the rectus femoris
- to decrease the load
- to decrease the starting angle of the ileo-psoas
Mutual flexion of the lower limbs and torso or "V-UP"
This is one of my favorite ab exercises. In it, the pelvis acts as a pivot and the action is due to the ileo-psoas and the rectus abdominis which, originating from the pelvis and crossing over, act as fixators.
Due to the intensity of this movement, which can be reduced by semi-bending the legs, it is not recommended to propose it to beginners or in a preventive and compensatory motor education program.
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