Physiology of Walking

One cycle walking / gait from heel starts one foot on the floor (heel strike) until the next heel strike of the same leg, called the 100% total walking cycle. Certain points in the cycle can be observed.
a. 0%: heel strike at the beginning phase of standing (stance phase)
b. 15%: front foot touches the floor, also known as flat foot
c. 30%: the heel off the floor (heel off)
d. 45%: knee and hip flexed to accelerate the leg forward, in anticipation of the swing phase (swing phase) called a knee band
e. 60%: fingers off the floor, the end of the phase of the standing to initiate the swing phase, called the toe off. In mid-swing required dorsiflexion of the foot to prevent fingers touching the floor.
f. 100%: back heel touches the floor.
During the total run cycle, phase stands covering 60% and 40% of total cycle is swing phase.

1.  0-15 % : heel strike phase
2.  15-30 % : mid stance phase
3.  30-45 % : push- off phase
4. 45-60 % : acceleration phase of the swing leg
At the end of the phase of one leg stand and the beginning of another phase of the standing leg there is a moment in which the body is supported by both legs . Double support phase lasted for 11 % of the cycle .
         Stride length ( stide length ) is the distance from one hell strike to the next heel strike of the same foot , the average 156 cm . Step length is the distance between the heel strike of one foot to the other foot , roughly half of the distance of stride length . Step width ( stride width ) is determined from the distance between the center line of the second leg , on average 8 approximately 3.5 cm . Angle of the foot ( foot angle ) is the angle formed at the step where the axis of the foot toward the cutting line to walk, on average 6.7 to 6.8 degrees . The duration of the cycle path is more than 1 second ( 1.03 approximately 3.5 ) . Number of steps ( step ) 117/menit , 60/menit stride . From the above figures , there can be many variations .

In the walking process requires :
a.  simple reflex mechanism at the level of the spinal cord . Postural reflexes and stand upright that defend the body by increasing tone of anti - gravity muscles , reflexes neck and labyrinth  to maintain tone  as needed,
b. upright reflex ( righting reflexes ) to maintain the position of the head , limbs and body ,
c.  integration of the functions of the motor cortex pyramidal ,
d. automatically through the basal ganglia mechanisms for posture , tone and movement -related as well as synergism ,
e. coordination functions of the cerebellum ,
f. sensory elements , especially proprioception to inform the individual position of each body part and to provide adequate space orientation . Spatial orientation is also obtained through visual Functions , especially when disturbed proprioceptive sensory function .

        During the walk , the weight supported by one leg while the other leg forward movement. At first , the support legs are fully extended with the heel first touches the floor ( heel strike ), then  knees bent makes an angle of 15 degrees when the front foot touching the floor as well ( mid stance), and then re-extension to lift the heel ( heel off ) when the center of gravity moves forward . Other legs start moving forward as soon as the weight was transferred to the support leg.

           Then the instantaneous weight supported by the heel of the leg moves forward, then by foot to the heel lifted and finally by the front foot. So the walking motion (gait) is a normal stage of laying a finger and heel forward. Slightly rotates the pelvis to the leg side moves forward (pelvis rotation of 40 degrees on each side), and down 5 degrees on the side of the swing leg (pelvic tilt). During walking, the leg also rotates, femur (8 degrees), tibia (9 degrees). from the beginning of the movement ( toe off ) leg suffered internal rotation which peaked in mid stance (15-20 % walk cycle), external rotation then occurs to push off phase. Along with the movement of the body and limbs, there is a member of the swing motion, which is associative in the opposite direction on each side of the limb .

Muscle activity in the walking cycle
       In the cycle of walking, the leg muscles are divided into several groups, among others pretibial muscle groups, muscle groups calf (calf), quadriseps group, hamstring group, group abductor, adductor group.

Pretibial muscle groups most active in the heel strike phase. In the stance phase there is little activity of this muscle because muscles dorsiflexion also an invertor-evertor. In the swing phase there is little activity of this group is the lifting your finger from the floor.

Calf muscle group especially the gastrocnemius and soleus, having maximum activity during push off to move the center of gravity forward.

Quadriseps group has maximum activity shortly after heel strike, work as shock absorbers when the knees bend. Rectus femoris muscle re-activated at the end of the stance phase when the hip flexion and leg move forward. The group is also active in producing the next swing of the lower limbs when hip flexion, this is an attempt to segment the lower leg segments to follow the upper limbs.

Hamstring group has two peaks in activity with time before and after heel strike. When not flat feet firmly on the floor, reducing the activity of this group of swing leg. When the foot has tread firmly on the floor of this group activity makes your knees bent. This group works as a shock absorber. End of the stance phase patients are second activity, the possibility to work on the hip and knee extension to push off.

Group abductor, gluteus medius and minimus especially active during the heel strike phase and early stance phase to stabilize the pelvic tilt. Adductor group has peak activity shortly after heel strike first, this is done by most of the adductor magnus governing internal rotation when the foot attached to the floor. The second peak of activity occurs at the end of the stance phase, in collaboration with the hip flexor muscles of the other leg accelerates forward as preparing to swing. At this time also plays a role in external rotation. Gluteus Maximus muscle during the most active phase of heel strike and work as shock absorbers. Other events occur when push off. Also assist the external rotation of the legs. Active spinal erector muscles during heel strike of each foot, which prevents the body bend forward at heel strike. The whole work this muscle group in the cycle runs only function within a short period and limited.

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