Modern surfaces, such as concrete, asphalt and floors, are far harder. When your feet land on them, the force of the impact is often more than your system can naturally absorb. The shock travels back up through the body, stressing and eventually damaging joints and causing fatigue. Excess weight, athletics, repetitive activities and standing for long periods can aggravate the situation. The heel strike shock particularly affects your lower skeletal frame --your knees, hips and lower back as well as your feet. In the long run, it can inflict pain, limit activity and in some cases, require joint replacement.
Due to fashion trends and cost cutting by manufacturers modern footwear rarely has sufficient cushioning. Most sports shoes which should offer better protection are rarely suitable for work or business use and studies have shown that most sports shoes lose much of their cushioning effect within a short time. For years, scientists have studied the problem and looked for possible solutions. Bio-engineers, orthopedic surgeons and physical therapists saw that, if they could find a way to place a shock absorber between foot and the ground, the energy would be diffused before it damaged the joints. For those already afflicted, such shock absorbers would help relieve pain and prevent further damage.
Studies were designed, experiments were conducted, materials tested. The results all suggested that visco-elastic polymers were the optimum materials for underfoot cushioning. These synthetic materials, which are both dense and elastic, proved remarkably able to absorb the shock of heel strike. Taking up less space in the shoe than conventional foam materials, visco-elastic polymers are the most efficient form of under-foot cushioning available today. In fact you would need up to 15 drug store insoles to equal the cushioning effect of one visco-elastic insole.
In tests that actually measured the amount of shock that various parts of the body sustained when walking, visco-elastic materials in combination with micro-porous foams showed far greater ability than other materials to dampen shock and reduce rebound. They cushioned the skeleton as the foot hit the ground and instead of kicking back instantly, they dissipated the energy evenly over several milliseconds. That is key to protecting the joints.