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By Root 298 0

there has been no decrease in the incidence (some authors say there has been an increase) of running injures in spite of yearly ‘improvements’ in running-shoe technology? Why is my office filled with runners who have injured knees (26% of running injuries), tibias (13%), Achilles tendons (6%) and plantar fascias (5%)? The cause of all these injuries is quite evident: cumulative micro-trauma caused by repetitive impact experienced during running. The heel of a runner upon striking the ground generates a force that can equal 2.5 times body weight at the foot and as much as 7 times body weight at the hip. Repeat this 1000 times per mile and it’s easy to appreciate the stress the old bones are under. Add to this the hardness of urban roadways compared to naturally deposited surfaces and eventually, something gives, inflammation sets in and pain results … and you end up working at the finish-line pulling bar-codes off finishers. Now, where’s our high-tech shoe in all this? With all the improvements in recent years, you’d think we’d be seeing a marked decrease in running injuries. Just keep reading.

It wasn’t till the mid-eighties that some researchers smelled something rotten in the athletic footwear world and it wasn’t just dirty socks. Footwear manufacturers were well aware that impact was the cause of running injuries and reasoned that the way to attenuate impact was to interpose a soft impact-absorbing midsole between the foot and the ground. The first major problem was the method used by essentially all the footwear development labs to test the impact absorption of footwear mid-soles. Dr. Benno Nigg from the University of Calgary showed that machine testing of these materials by dropping a 5-kg object onto the shoe-sole and measuring the impact on a pressure-plate did not accurately predict human impact with the same materials. In fact the correlation turned out to be inverse, that is when you drop a 5-kg ball on materials of increasing softness, you measure decreasing impact. However, when the impact from a running human is measured, the result is the reverse, and the impact increases with softer materials! WHOOPS! (You’ll find out why later.)

Next problem. In 1989, Dr. B. Marti published a paper which still makes the throats of footwear executives go dry. He studied 5,038 runners who participated in a 16K race and had them fill out an extensive questionnaire about their running in the year preceding the race. Here’s what he found: The incidence of injuries in runners using shoes costing more than $95 was more than twice as great as in runners using shoes costing less than $40. (Note that this result includes correction for other influencing factors such as training mileage and history of previous injury.) In other words, the fancier (high-tech, advanced) the shoe, the more dangerous it is! Now a study of over 5,000 runners is not something to thumb your nose at and you would think the shoe manufacturers would have taken some notice. Not on your life. Yearly athletic shoe sales were in the billions of dollars and this was no time to fiddle with a successful product. In any case, it is felt by many observers that by the mid-eighties researchers, in-house or independent, had effectively been forced out of the loop of new product development and that research and development was now exclusively in the hands of the marketing people. Athletic shoes had become a fashion item and were designed as such, as they are to this day.

The big question: Why are super shock-absorbing athletic shoes causing more running injuries? Dr. Steven Robbins from the Centre for Studies in Aging at McGill University in Montreal is the man who came up with the answer. Dr. Robbins pointed out that the human lower extremity is not a delicate, rigid, passive structure requiring ‘packaging’ to protect it from impact. This becomes blatantly obvious when one observes the nearly complete absence of foot disorders in unshod populations. People who go around barefoot just don’t get plantar fasciitis or any of the other lower extremity injuries so common in