2014, Volume 10, Issue 1

Similarities and differences of body control during professional, externally forced fall to the side performed by men aged 24 and 65 years

Robert Michnik1, Jacek Jurkojć1, Piotr Wodarski1, Dariusz Mosler2, Roman Maciej Kalina3

1Biomechatronics Department, Silesian University of Technology, Zabrze, Poland
2Student scientific circle “Health Promotion – Interdisciplinary Approach” at the Faculty of Physiotherapy, Department of Health Promotion & Research Methodology, Academy of Physical Education, Katowice, Poland
3Department of Combat Sports, Gdańsk University of Physical Education and Sport, Poland

Author for correspondence: Roman Maciej Kalina; Department of Combat Sports, Gdańsk University of Physical Education and Sport, Poland; email: kom.kalina[at]op.pl

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Background and Study Aim: Cognition of kinematics of body movement during balance loss, fall and collision with the ground in various circumstances is a basic condition of both expanding our knowledge of these phenomena and optimizing effective prevention of falls and collisions with the ground and vertical obstacles. The aim of the study is to determine whether a substantial difference in age of men training combat sports results in differentiation of body balance during professional, eternally forced fall to the side.
Material and Methods: Two men have been subjected to the study: 65-years-old scientist (A), who has been training judo and other combat sports for over than fifty years and is professionally involved in teaching people how to fall down safely; 24-years-old physiotherapist (B), who trains judo as an amateur, have completed specialist course on safe falling and used those exercises in his kinesitherapy practice (including patients with psychological disorders). The analysis of kinematics of body movement during forced fall has been performed by an assistant. Tested person was trotting in place on the hard ground and each ankle joint was wrapped with a separate judo belt (obi). The assistant was knocking each joint out of balance by pulling one of the belts. Tested person was not aware in which direction (right or left side) he would be knocked out by the force causing the fall. The analysis included four falls to the left side. Measurements have been performed with the use of MVN Biomech system (XSENS) based on inertial sensors equipped with accelerometer, gyroscope and magnetic field sensor.
Results: Most falls of both subjects are similar in terms of duration and trajectory of the mass centre. The beginning of lowering mass centre occurs later in person B. At the end of the performance of the fall person A causes a slight flattening of the trajectory of the mass centre which may indicate that such preparation of the body and movement of its parts is to slightly decrease the vertical speed of mass centre before contact with the ground. Person B finishes the fall with setting the torso angle of around zero degrees relative to the ground (therefore, directly after collision with the ground it is relatively motionless). After reaching zero degrees, the torso angle of person A passes to negative values (–25°), indicating performance of rolling the trunk. Such behaviour allows for additional dispersal of energy reducing thereby the force of body impact on the ground.
Conclusions: The retirement age does not necessarily involve a deterioration of ability to control the body during unintended fall and collision with the ground. On the contrary, suitable training results in the fact that such person can optimally protect his body in such circumstances and function more effectively in comparison with considerably younger people. Obtained results are, moreover, an empirical proof of methodological correctness of safe falls modelled on techniques used in judo (ukemi waza).

Key words: biomechanics analyses, injury prevention, ukemi waza