The Foot Position affecting Stance
The foot plays two important role in human stance; First, the two arches of foot (Longitudinal and Transverse arch) elastic in nature are responsible for absorbing the shock and provide great strength and stability. Second, they affect the knee & Hip mechanics in closed kinetic chain Asana's like (Utakatasana (Chair Pose), Veerabhadrasana (Warrior's Pose) where the foot is firmly planted to recruit core or proximal muscles.
There are two foot position
First, Toes together heels apart where thighs are rotated medially (Heels open 45 degree each=90 degree opening at rear)
Second, Heels together toes apart: Thighs rotated laterally (Toes open 45 degree each=90 degree opening at front)
In both situation thigh rotation accounts only about two-thirds of the total rotation - 30 degree at the hip and 15 degree at the ankle.
As mentioned in my previous article the Femoral internal rotation is the same as tibial external rotation or vice versa, Rotation/slippage of the foot is translated to the thigh, If a foot slips out of position in a standing posture, it indicates weakness on the side of slip; For example, when standing in any Warrior pose, if the foot of front leg turn out or the heel slips in (most commonly seen while trying to alight the flexed knee with hip) that shows the weakness in group of Synergists (assisting) muscles creating medial rotation of flexed knee (Semitendinosus semimembranosus, Gracilis and Sartorious) on the front leg and tightness of its Antagonist muscles (Biceps femoris) in same leg.
Another example is Warrior III where the heel of the standing leg has tendency to slip out while Most students tend to extend or hyperextend the knee of standing leg. This slippage is due to the imbalance in deep hip rotators, flexors and abductors that can be confirmed with an overhead squat assessment or by noticing the inability to raise the free/gesture leg at the level of respective hip in warrior III with knee flexed (of standing leg).
Role of Foot and ankle dysfuncion in Standing Balancing Asanas
One of the hallmarks of lower leg (Foot, Ankle & tibio-femoral joint) dysfunction that affects standing balancing asana's is the inability to adequately dorsiflex the ankle leading to a compensatory pattern that includes “turn-out” of the feet in overhead squat assessment, during eccentric deceleration of jumping forward or backward in vinyasa, difficulty in bringing the heels to floor in downward facing dog and yogic squats etc.
The amount of turn-out observed in individuals with significant dysfunction (often 30-45°), cannot be achieved via subtalar abduction alone. Some portion of this rotation is happening at the tibio-femoral joint/knee joint (optimal available range for tibial external rotation = 45°). The Knee assumes a position of lateral rotation and adduction. Because many of the rotators of the knee also cross the hip; the hip mechanics are also affected, and the intricate mechanics of tibia and femur result in tibial external rotation being synonymous with femoral internal rotation.
Ankle dysfunction quickly leads to inhibition of the gluteus medius and an alteration in hip muscle recruitment. This is made worst by short/overactive TFL that glides the hip anterior and superior in joint capsule, resulting in hip impingement syndrome, and hypertonicity of the quadratus lumborum and adductors resulting in dyskinesis and a reduced ability to stabilize in the frontal plane in Hatha Yogasana like Natarajasana (lord of dance pose) and Veerabhadrasana III (warrior III pose).
In long term, this chain reaction from ankle to hip and hypertonicity of hip flexor along with synergistic dominance of deep rotator of hip leading to an anterior rotation of hip and counter nutation of the SI joint, further increasing the Instability at hip and pelvis causing drop of pelvis and inability to balance on affected side in one leg standing balancing asana and may result in
- Adaptive shortening of the biceps femoris, sacrotuberous ligament, and potentially the erector spinae
- Adaptive shortening of the tensor fascia latae, the iliotibial band, and the investing fiber of the vastus lateralis
- Adaptive shortening of posterior ankle fascia
This implies that focus should be placed on inhibition of the deep longitudinal subsystem, integration of the posterior oblique subsystem, and a focus on increasing frontal plane stabilisation.
(“Second Law of Human Movement Science: All bones move relative to other bones”– i.e. Femoral internal rotation is the same as tibial external rotation)