Shock absorption and pressure distribution

In recent years a great deal of marketing attention has been focused on shock absorption in shoes or mats in respect to relieving fatigue and stress especially in the knee, hip and back.

The sole of a bare foot has a certain capacity to perform the necessary shock absorption in natural surroundings. However, many workers wear work boots and some either stand or walk as much as 95% of the time on concrete surfaces. This results in an increased biodynamic load that increases the long term risk of injury due to constant jarring and jolting to the heel, knees, hips and back. We are very sensitive to concentrated impact pressures all along the kenetic chain that includes the heel, ankle, knee, hip, back and spine. The heel bone is subject to impact forces of up to 4 to 5 times body weight during walking and to avoid concentrating pressure on the heel bone it is necessary that the heel has a large support surface area to absorb shock by redistributing force. Our body provides a fatty tissue layer that supports the heel bone. This heel pad is the most important shock absorber in the foot. The tissue layer is made up of large closed compartments filled with dynamic fat into which the heel bone settles and dispurses pressure during heel strike. When walking or running the heel bone utilizes the tissue layer to achieve natural hydraulic pressure redistribution and absorption.

It is important to note that a great deal of the shock caused by heel strike on concrete floors is not absorbed by the heel fat pad. Impact that is not absorbed by the heel pad is dissipated by transmition of the shock up the kenetic chain and is known to be responsible for leg, knee, hip and back fatigue and pain.

The role of circulation in industrial foot health

Lower extremity circulation is greatly dependent on constant movement of muscles in feet, calf and thighs. The venous system is based on using muscle activity to provide the pumping action necessary to return blood to the heart. Veins are closely connected to the muscles in such a manner that when a muscle contracts the vein is compressed ejecting blood through the one way venous valves on it’s way towards the heart. When the muscle is relaxed blood refills the veins.

Tired, sore and aching feet and legs are attributable to reduced circulation in the feet and legs caused by the lack of muscle activity in shoes. This is very apparent in occupations requiring standing and walking on hard surfaces. When workers are standing in one place or walking in shoes there is reduced muscle movement in the foot. That results in reduced blood flow throughout the lower extremities. It is the lack of oxygen and nutrients to the cells that results in foot pain, swelling and fatigue. Fatigued foot muscles create a domino pain effect as they reduce flexibility, create further stresses to the foot and cause many people to assume awkward postures in an attempt to alleviate pain. It is those postures that also place stress on knees, hips and the back.

R. Dan Allen is the president of Foot Happiness LLC. For more information or to contact him, visit www.FootHappiness.com.