IMPACT FORCES AND MOVEMENT CONTROL -TWO NEW PARADIGMS

In the last century, participation in physical activities has developed dramatically. The best documented development was in running with millions of participants (6, 24). Between 1978 and 1983, the number of runners in Canada has more than doubled from 15 % to 31 %, but has decreased in 1988 to about 18 % of the total population (50, 56). The high incidence of injuries in runners has been proposed as one possible reason for this decrease. Between 37 to 56 % of all runners are injured during a year of running (31) and running injuries make up the majority of sport related injuries in the young (31.5 %) and the old (40.5 %) physically active population (29). Major reasons for the development of exercise related injuries proposed in the literature include previous injuries, training errors, excessive impact forces and excessive foot movement or movement control (8, 9, 21, 31). From a biomechanical point of view impact forces and movement control are of interest since they can be influenced with the sport shoe. This paper will concentrate on these two aspects and propose two new paradigms for the functional understanding of impact forces and movement control