# IMPACT FORCES IN SPORT PAVEMENTS MEASURED ACCELEROMETRIC METHOD

• Juan V. Dura
• L. Lozano
• A. Forner
• J. Ramiro
• P. Vera

## Abstract

It has been documented that repeated impact forces can lead to injury (VOLOSHIN, NIGG, etc ) Although there are different mechanical methods in literature, even in normative (DIN 18032), there are few studies with subjects about the influence of sport pavements In Impact forces May be the great within-subject variability in these experiments is a reason for the scarcity of results The purpose of this study is validate the accelerometric method and to determine the influence of impact forces of two different prototypes of indoor pavements a wooden pavement and a cork pavement We established a concrete pavement like reference surface The two pavements carry out the requirements of vertical ball behaviour in DIN 18032 normative The methodology consist in putting two accelerometers: one on a tibia and another on a head. Six subjects did forty five jumps over the three pavements: fifteen over concrete, fifteen over wood and fifteen over cork. The jump was the 95% of the maximal jump in every subject and the sequence of jumping was randomized to avoid adaptation to the pavement. The signal of accelerometers was amplified and digitized in a personal computer at I KHz sampled frequency. Different parameters were extracted from the acceleration-time curve: forefoot contact. heel contact, a severity index. maximal acceleration and minimal acceleration. The variability within-subject were high: sometimes. the forefoot contact acceleration was higher than heel contact acceleration and sometimes the other way round; but we found very significati1.e levels in maximal accelerations. We did an ANOVA with two factors: pavement, and subject. There are significative levels of 0 0004 for the maximal acceleration of the tibia and 0.0001 for the maximal acceleration of the head. The difference between cork pavement and wooden pavement \vas not significative. The two pavements were significative different of concrete With the values of mean squared residuals obtained and a=O 05 i t is possible to calculate the power of tile F-test. then we can find differences of 0.3 g from the head and 0 S g from the tibia So we can deduce that the differences between the two indoor pavements are lower than 0.2 g from the head and 0 S g from the tibia