Analysis of walking in Anatomy

ANATOMY OF A WALK

Walks are very complex. Not only do the feet have to move across
the ground, but the hips, spine, arms, shoulders and head all move
in sync to maintain balance in the system. Though complex, if you
break down each of these movements joint by joint, the mechanics
of walking become clear.


Let’s break down a basic walk, step by step. For clarity, I’ve animated
a simple skeleton so you can see exactly how each joint moves.


THE FEET AND LEGS

The feet and legs propel the body forward. To keep your character
looking natural, you should always keep the joints bent slightly,
even at full leg extension.


The walk usually starts with the feet at the extended position – where the feet are furthest apart. This is the point where the character’s weight shifts to the forward foot.

As the weight of the body is transferred to the forward foot, the knee bends to absorb the shock. This is called the recoil position, and is the lowest point in the walk

This is halfway through the first step. As the character moves forward, the knee straightens out and lifts the body it’s highest point. This is called the passing position because this is where the free foot passes the supporting leg.

As the character moves forward, the weight-bearing foot lifts off the ground at the heel, transmitting the force at the ball of the foot. This is where the body starts to fall forward. The free foot swings forward like a pendulum to catch the ground.

The free leg makes contact. This is exactly half the cycle. The second half is an exact mirror of the first. If it differs, the character may appear to limp.

THE HIPS, SPINE & SHOULDERS
The body’s center of gravity is at the hips -- all balance starts there, as does the rest of the body’s motion. During a walk, it’s best to think of the hips’ motion as two separate, overlapping rotations. First, the hips rotate along the axis of the spine, forward and back with the legs. If the right leg is forward, the right hip is rotated forward as well. Second, at the passing position, the free leg pulls the hip out of center, forcing the hips to rock from side to side. These two motions are then transmitted through the spine to the shoulders, which mirror the hips to maintain balance.




When the feet are fully extended, the hips must rotate along the axis of the spine. To keep balance, the shoulders swing in the opposite direction. From the front, the spine is relatively straight, but from the top, you can see how the hips and shoulders twist in opposite directions to maintain balance.



At the passing position, the front view shows the hip being pulled out of center by the weight of the free leg. This causes a counter-rotation in the shoulders. From the top, however, the hips and shoulders are nearly equal angles.





At the extension of the second leg, the hips and shoulders again are flat when viewed from the front. From the top, however, you can see the rotation of the hips and shoulders has completed.

THE ARMS
Unless the character is using it’s arms, they’ll generally hang loose at the sides. In this case, they generally act like pendulums, dragging a few frames behind the hips and shoulders.
Even at full extension, try keeping the arms slightly bent at the elbows. This will keep them looking natural.

THE HEAD
In a standard walk, the head generally tries to stay level, with the eyes focused on where the character is going. It will then bob around slightly to stay balanced. If a character is excited, this bobbing will be more pronounced. The head may also hang low for a sad character, or may look around if the scene requires it.

Credit for www.rubberbug.com