Newswise — Scientists of the Immanuel Kant Baltic Federal University and colleagues from Innopolis University jointly developed a mathematic model which enables to describe the process of stabilization of unsteady position to the equilibrium state. On the basis of this model the authors found out that short trainings aimed at keeping balance help to lessen the differences between the right and the left limbs. The results of their research are published in Chaos, Solitions and Fractals.
To plan physical loads correctly it’s vital to know how human body adapts to them in the course of short-term trainings. Moreover, the modelling of the training process enables to understand the process of education by exercising. Besides you always have to bear in mind that people are characterized by functional asymmetry, when one of the limbs tends to be the leading one. And if you overload the “dependent” arm or leg, it may cause athletic injuries such as spraining or fractures.
Scientists of the Immanuel Kant Baltic Federal University (Kaliningrad), the Innopolis University (Innopolis) and their colleagues from Polytechnic University of Madrid (Madrid) described the work of different muscles of the human body in the course of short-term trainings on the balancing platform. Sixteen volunteers – healthy right-handed middle-aged men from the University of Innopolis took part in this research. The participants trained equilibration in three rounds of ten-minute exercises, when they have to stay on unsteady desk, the central part of which was connected with rotary attachment. This platform reminds a lever, inversed pendulum and a seesaw, the desk of which, without a child on its opposite sides, is drooped leftwards or rightwards due to gravity. To hold the equilibration, you have to keep the platform almost parallel to earth surface, using the work of muscles and shifting masses’ of the body center.
In the course of the experiment the authors estimated the mode and speed with which the grade angle of the desk changes, when you stand on it, and also the activity of muscles which take part in holding the equilibration. To achieve this, the scientists fixed the electrodes on the area of the flexor and extensor muscles of the lower leg and thigh’s skin of the participants.
The main difference between this particular experiment and many others lies in that a test person has to find the most effective strategy of platform handling actively by himself, without any recommendations and directions.
It turns out that short-term training aimed at holding equilibration influences the efficiency of handling of multistability of the platform, that means that the system with two stable conditions – when the platform is drooped leftwards or rightwards – transformed into the system with three stable conditions under the influence the test person – it was supplemented by the position parallel to the earth surface. To describe this process the authors used the mathematic model, based on the Fokker-Planck equation, which explains the behavior of the particle in the potentional well. The potentional well is the area in which the object possesses the less amount of potential energy. This very position is considered to be the most stable one. In course of the experiment, as the result of the training the condition of the system “a test person on the platform” changed so that potential well, corresponding to the third, initially unstable condition, tends to deepen. All this proves the fact that a test person successfully solves the task of diminishing the potential energy of the platform, otherwise speaking, increases the stability of it without changing the characteristics of the system directly.
The authors proved that platform’s motion trajectory during the experiment was asymmetrical due to domination of the right part of the test person’s body over the left one. Thus, angle speed of the platform on the side of the left leg was higher, than on the right one, and the work of the corresponding muscles increased. As a consequence, ‘the leading” limb was under a bigger pressure and provided better balance control. However, by the third training the asymmetry almost completely disappeared, that indicates that trainings helped to lessen the difference in the amount of work provided by the “leading” and “dependent” muscles.
“Short-term trainings on the balancing platform enable to improve coordination in quite a short period. Thus, the time when volunteers managed to hold on the desk, increases more than by half, only after 30 minutes of the experiment. Besides this, the participants overcame the asymmetry of the right and left legs. In future we plan to make researches of the longer trainings, in order to estimate their effects.” – tells Alexander Hramov, professor, Doctor of Physical and Mathematical Sciences, the head of Neuroscience and Cognitive Technology Laboratory of the Innopolis University, the Chief Researcher of Neurotechnology and Machine Learning Center of Immanuel Kant Baltic Federal University.
“The research of the process of human’s handling the complex objects in space is very important for understanding the processes of the education. In future it can be useful for perfecting such machines as bipedal robots,” – comments Vladimir Horev, Candidate of Physical and Mathematical Sciences, senior research scientist of Neuroscience and Cognitive Technology Laboratory of the Innopolis University.
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