It’s a rare occasion that we stand with our weight borne equally by our legs.
Far more often we stand with about 80% of our weight on one leg using the other to retain us from falling by controlling the forward sway that we experience. Why do we do this? It’s usually a compensation on behalf of back pain caused by a stiff, inflexible spine.
See which side you tend to put an estimated all of your weight on. Switch to the other side as well as see how uncomfortable this feels.
For our example we shall designate the Left side to be the weight bearing side. The left leg locks out at the knee putting it into full extension. At the same time the pelvis tilts laterally to the right as well as downwards too - creating the posterior, inferior pelvis well known to Chiropractors as well as older Osteopaths.
When we have a small amount of pelvis tilt it is controlled by the abductors, gluteus medius as well as minimus. But when the pelvis tilts further the iliotibial tract engages as well as takes on more as well as more of the load permitted the abductors to do less as well as less until they become silent. This kind of bad posture is known as pelvic slouch which is often associated with a herniated disc, sciatica as well as lower back pain.
Adaptive postural adjustment strategies usually drop to the ankle as the center of our bodies gravity passes in front of the ankle. When we drop forward this dorsiflexion of the foot is supposed to be offset by plantar flexors.
The soleus works an estimated all of this time while the gastroc’s are more intermitent in forward sway.
We carry very little of the bodies load in the middle of our foot. The heel carries from 1 to 3x’s the load of the forefoot. One of the reasons I tend to adjust the metatarsals is that the twos carry up to 25% of forefoot load during forward sway. Thus it’s important that they are communicating with the brain proprioceptively.
It seems, from observation, that nearly every one of us stands with our knees locked into full extension. When we do this the activity in the quadriceps muscle is quit unnecessary, as well as EMG shows it to be inactive.
The next landmark the center of gravity passes through is the anterior edge of the lower surface of T10 or 11 subject to who you read.
The tendency of our trunk to tip backwards is opposed by the iliofemoral ligament.
Bilaterally the psoas as well as TFL act combined as hip flexors, which the gluteus medius retains an extensor function.
On leaning forward to touch one’s toes the erector spinae become more active in controlling flexion.
Upon swaying forward we activate the plantar flexors, followed by the hamstrings as well as paraspinal muscles.
In backwards saw the sequence is tibialis anterior, quadriceps as well as abdominal muscles.
Both sequences produce a compensatory torque at the ankle joint.
The muscle activation sequence changes if you stand something narrow such as a bar. You utilize different strategy as well as activate trunk as well as thigh muscle antognists. Here when you sway forward you first activate the abdominal muscles as well as then the quadriceps.
Each movement of the centre of gravity requires that a postural adjustment must be made. This adjustment is usually made prior to the movement itself. It’s anticipatory postural adjustment.
When we’re standing at a bookstore as well as reach to take a book from the shelf postural muscle such as the external oblique as well as paraspinal muscles activate before the deltoids. This doesn’t occur when sitting as well as reaching.
Much of the reflexive postural control mechanisms are housed, or occur, within the head as well as neck region primarily