The influence of footwear and surfaces on performance and injury potential in running

Abstract

The focus of this project was to detect differences in running gait (at a fixed speed) induced by differences in shoes and surfaces. A review of the literature indicated that improvements in the measurement and analysis techniques were necessary to yield results accurate and reliable enough to. detect these differences. A pilot study was therefore performed to evaluate the magnitude of the measurement errors and the repeatibility of the results.
One subject completed 98 trials (emcompassing 10 different shoe­surface conditions) at a fixed speed (approximately 4.46 m/sec) and the vertical (FZ) and horizontal (FY) ground reaction forces were measured. Parameters were developed ·to completely describe the characteristics of the ground reactions (FZ, FY). A statistical analysis performed using these parameters concluded that 10 trial repetitions were required for a reliable result. An X-ray study of one subject was also performed. This study evaluated the errors due to skin markers ( used for filming) moving with respect to the underlying bone. As a result of the X-ray study a new technique to reduce the marker motion errors was developed, tested and found to be potentially powerful.
On the basis of the pilot study, the main experiment was designed to test five male subjects under four shoe-surface conditions. High speed films in conjunction with force platform data were collected. A two-dimensional model of the human leg was employed to yield resultant forces and moments at four joints (hip, knee, ankle and metatarsophalangeal). Parameters were developed to describe these resultants. The force parameters, joint resultant parameters and shoe /surface parameters (from friction, resilience and flexibility tests of the shoes) were correlated and discussed in relation to performance and injury potential. Methods of applying the conclusions to shoe and surface design were suggested.