This article provides methods for evaluating the parameters of the balance of the human body by applying accelerometry and evaluates the impact of physical load on the human body balance parameters. The work is aimed at assessing and comparing the parameters of static balance in comparatively healthy adults (20–25 year-olds) before and after physical activity. Accelerometry is one of the newest and alternative methods for research and evaluation of balance. This method is related with a posturography method; however, differently from applying the posturography method in research, no laboratory conditions and expensive equipment are needed for it. Movements of the head with respect to the trunk are recorded by means of accelerometric method even before the changes in the position of the centre of the body mass, measured by a force plate, appear. During accelerometry, the triaxial accelerometers are used that are attached to the trunk and the limbs of the subjects under study as well as computer equipment for processing of the signals measured. Speeds and accelerations of the movement of the body parts are determined by accelerators. Seeking to assess and compare the parameters of static balance in humans before and after physical load, an experimental human balance test has been conducted with the application of accelerometry. The test was conducted with 11 healthy volunteers, the main parameters of which are provided in Table 1. Prior to starting the test, blood pressure and heart rate of the volunteers was measured. During the experiment, the following main tools and supplementary equipment were used: three seismic (uniaxial) accelerometers 8344, which traced the oscillation amplitude of human centre of mass for the axes X, Y and Z. Technical characteristics of the accelerometer 8344 is as follows: sensitivity 250±20% mV/ms–2, measure range ±26 ms–2, frequency range 0.2–3000 Hz; portable computer with special software package Pulse; Electrical signal input and processing device 3660-D; veloergometer. Accelerations are registered by means of the accelerator, wherefrom by program integration twice a change in the centre of mass of a human body is received. Having a change in the centre of mass, the trajectory of the centre of mass in the horizontal plane (XY plane) may be reflected for the axes X, Y and Z. After performance of experimental research of human balance with the application of accelerometry methods, it has been established that: a) comparing the amplitude of oscillations forward/backwards with eyes opened before and after physical load, it has been noticed that the amplitude of oscillations after physical load with eyes opened increased by 22.48 percent. With eyes closed, the average of amplitude of oscillation forward/backwards before physical load is 0.0120 m, and after physical load 0.0141 m. Comparing the amplitude of oscillations forward/backwards with eyes closed before and after physical load, it may be noticed that the amplitude of oscillations after physical load with eyes opened increased by 14.99 percent. b) comparing the amplitudes of oscillations forward/ backwards and sideways experimentally received from accelerometers it is possible to state that central vision enables to identify the surrounding objects, parts of the body and their parameters. Peripheral vision has a greater impact on oscillation forward/backwards than on left/right. Meanwhile, central vision participates in oscillation control of both motion modes.

The article provides an analysis of experimental and analytical investigation of human balance assessment using accelerometry methods. The experimental findings were processed by applying statistical and digital methods; comparative analysis of the balance assessment method was carried out, the reliability of the method and opportunities for practical application were evaluated. Accelerometry is one of the most advanced methods of balance investigation. This method is related with posturography technique; laboratory conditions, however, when using the accelerometry method are not required. Movements of the head in relation to the trunk are recorded by the accelerometry method even earlier than the changes in the posture of the centre of mass appear which are measured by a force platform. During the accelerometry, triaxial accelerometers, fixed to the trunk and the limbs of the subject under study, and hardware for processing of the measured signals are used. Speed and acceleration of the movement of the parts of the body are determined by accelerometers. Such examination may be used for assessing the body balance in patients with vision impairments, brain injuries, problems with the limb control, etc. The purpose of experimental tests is to evaluate and compare the parameters of static balance in healthy adults (20–25 year-old) before and after physical Human body stability investigation activity utilizing accelerometry. The main parameters of the subjects under study: age 21.83 ± 3.17 years, height 170.63 ± 13.37 cm, weight 66.09 ± 16.91 kg, BMI 22.62 ± 5.02 kg/m2. “Bruel&Kjaer” measuring equipment was used for experiments: three seismic (uniaxial) accelerometers 8344, which traced the oscillation amplitude of the human centre of mass for the axes X, Y and Z. Technical specifications of accelerometer 8344: sensitivity 250±20% mV/ms–2, measurement limits ±26 ms–2, frequency range 0.2–3000 Hz; the portable computer with Pulse special program package and electrical signal input and processing facilities 3660-D. After the investigation it was determined that during physical load the permanent functional condition of the human organism undergoes changes, its various functions and structures have to adapt to psychophysical loads in order to function reliably, therefore the vibration amplitude after the physical load increases. Comparing the values of the standard deflection of vibration amplitudes for X and Y directions before and after physical load, it was received that a standard deflection for X direction (comparing the results before and after load) increases, on the average, by 3.7 times, and for Y direction by 2.7 times.