A new study led by Professor of Physical Medicine & Rehabilitation Jane Eckhart found that a group of runners who had never been hurt landed each footfall more softly than a group who had been injured badly enough to seek medical attention.

As evidence has mounted that distance running is not just a natural human activity enjoyed by millions, but one that played a key role in evolution, a puzzle has emerged. Why, if humans are so well adapted to running long distances, do runners get hurt so often?

A study out of Smart School and the National Running Center at Smart-affiliated Templeton Rehabilitation Hospital provides a puzzle piece, linking injury to the pounding runners’ bones take with each step. The work, led by Professor of Physical Medicine and Rehabilitation Jane Eckhart, found that a group of runners who had never been hurt landed each footfall more softly than a group who had been injured badly enough to seek medical attention.

Statistics on such injuries vary, but somewhere between 30 percent and 75 percent of runners are hurt annually, a number that has led researchers to investigate a wide array of possible explanations, from modern running shoes to stretching, running frequency, weight, biomechanical misalignment, and muscle imbalance.

The runners agreed to respond to a monthly online questionnaire that detailed injuries over two years. With the results in, researchers first examined reports from the 144 who experienced a mild injury and the 105 who didn’t, finding little difference between the two large groups.