The leading cause of accidents in the home and the workplace is slipping, tripping and falling. According to the 2007 Edition of the National Safety Council, Injury Facts, the leading cause of non-fatal unintentional injuries is still falls. The leading cause of injury-related Hospital Emergency Department visits is still accidental falls, and in the category of principal types of unintentional-injury deaths is motor vehicles, but still second is falls. Mechanically speaking a fall occurs when the center of mass (weight) of the individual is no longer balanced over their support (feet/legs). When balance is lost, for whatever the reason, the individual will fall. During ambulation, walking on walkways or stairs, this principally occurs when the individual's gait is disturbed. This can occur is several ways, by slipping, by tripping or by an unexpected or nonoccurrence of their step (foot) location. In this discussion, I would like to first discuss what is human gait, what affects it and thereby what causes individuals to fall during ambulation. From that knowledge, we can discuss and learn how to prevent these falls.
Walking is initiated, from a static standing position by moving the center of mass of the body forward (or backward) creating an unbalanced condition, then swinging one leg/foot forward (backward) and landing it ahead of the body's center of mass. The body's center of mass, then passes over the forward now landed foot, and continues forward (backward) creating anothern unbalanced condition. The trailing foot is then swung forward (backward) and landed ahead of the body's center of mass, to catch the body and preventing it from falling. The body's center of mass then continues moving forward (backward) and the trailing leg is then swung forward and lands continuing in this fashion until the motion is stopped by not allowing the center of mass from passing forward (backward) of the legs or vertical support position.
This results in three critical positions:
Landing the forward (swinging) foot commonly referred to as: "Heel Strike."
Swinging the trailing foot.
Lifting the trailing foot commonly referred to as "Toe Off" or "Push Off."
The most critical factor in the heel strike and toe off positions is the slip-resistance of the walkway surface. The individual determines what the slip-resistance of the walkway surface is by, first visually observing the walkway surface and optically calculating what they expect the slip-resistance to be. They then cautiously place their foot forward and test or confirm that the actual slip-resistance is what they had calculated. Then after the individual has determined and confirmed the slip-resistance, they will set their gait (step length) accordingly and proceed to walk on that surface. When the individual reaches a spot or area where they have visually determined that the slip-resistance of the surface may be different, they will go through this process again, recalculate, re-test and reestablish their gait.
