2015, Volume 11, Issue 1
Similarities and differences of the body control during professional collision with a vertical obstacle of men aged 24 and 65
Robert Michnik1, Jacek Jurkojć1, Piotr Wodarski1, Dariusz Mosler2, Roman Maciej Kalina3
1Biomechatronics Department, Silesian University of Technology, Zabrze, Poland
2University School of Physical Education in Poznań, Poland
3Department of Combat Sports, Gdańsk University of Physical Education and Sport, Poland
Author for correspondence: Robert Michnik; Biomechatronics Department, Silesian University of Technology, Zabrze, Poland; email: robert.michnik[at]polsl.pl
Background and Study Aim: Both the epidemiology of body injuries due to collision with vertical obstacles or objects in motion and the prevention of such events are very rarely discussed in the scientific literature. Understanding the kinematics of body movement during a collision with vertical obstacle may constitute a significant element used to create rational methodology for injury prevention in these circumstances. The aim of the study is to answer the question whether significant age difference of men training combat sports results in differentiation of the body control during professional collision with hard vertical obstacle forced by an external force and as a consequence whether it affects the way to protect head in particular and the amount of dissipated energy.
Material and Methods: Two men have been subjected to the study: a 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; a 24-years-old physiotherapist (B), who trains judo as an amateur, has 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 a collision with vertical obstacle was conducted. The collisions were forced by the assistant. Tested person was standing freely (with muscles relaxed) facing the front of the concrete wall at the distance of 2 metres. Assistant pushed the tested person each time towards the wall with similar force in the same way (by pressing the neck with one hand and lumbar spine with another). Measurements have been performed with the use of MVN Biomech system (XSENS) based on inertial sensors equipped with accelerometer, gyroscope and magnetic field sensor. The analysis involved four registered collisions with the wall of each tested person.
Results: Since the contact of the upper limbs with the wall to the moment of stopping the body centre mass movement, both men shielded and protected the head by lifting their arms up and simultaneously flexing the arms in the elbows. This proves that the body surface in contact with the obstacle is almost identical in both men. Men A more effectively amortises the collision with the vertical obstacle. This is reflected in the average values of the head mass accelerations, which were lower by approx. 16% than in man B; the average energy absorbed by the body tissues of man A amounted to approx. 77%, whereas man B to 91% of the collision energy (man A dissipated energy more effectively). More effective amortisation of the collision with vertical obstacle by man A resulted moreover from the movements of his body segments after the collision (mainly flexing the knees, which is possible due to the relaxation of the muscles around this joint). The movement of body segments of man A in the second phase results in the increase of the mass centre movement in the direction of sagittal axis and in the increase in the body movement range.
Conclusions: Suitable training causes the person in retirement age to more effectively amortise the collision with own body with hard vertical obstacle than a young adult man with significantly shorter training experience. Completion of the specialist course on safe falling and several years of judo practice significantly increase the abilities of protecting the body of a person in the conditions, when an external force results in the collision with the hard vertical obstacle. Increased probability of the more effective prevention of body injuries or even death in such circumstances requires the inclusion of such simulations to the permanent health-related training.
Key words: biomechanics analyses, body injuries prevention, health-related training, safe fall theory