## 1 Introduction  
In many studies, the terms centre of gravity or centre of mass are used interchangeably. These concepts are often confused and usually equated [1]; therefore, for clarity, both concepts and their relationship are explained below. The **centre of gravity of a body (_CoG_)** is defined as the point at which the resultant of the gravity forces of all body elements is applied, and the total gravitational moment acting on the body is zero, which causes the body to be in a state of equilibrium. This point is independent of the body's position but depends on its shape and may lie outside it. Changing the shape of the body is equivalent to changing the position of the _CoG_. The **centre of body mass (_CoM_) is a more general concept than the centre of gravity because a body always has a centre of mass regardless of whether it is in a gravitational field or not. It is a point that behaves as if all the body's mass were at that point and as if all external forces acting on the elements of that body were applied to that point. If a force acts on this point, the body will accelerate linearly but will not rotate. The interchangeable use of the terms _CoG_ and _CoM_ in the context of research on the human body results from the fact that for objects of uniform density, in a uniform gravitational field, the centre of gravity coincides with the centre of mass. The smaller body's size justifies this approximation in comparison to the size of the Earth and the distance of this body from its centre. Currently, there are several methods known for determining the centre of gravity of the human body in practice. These are as follows:  
* The method of balancing the body (one-sided lever method) through placing horizontally on a special platform supported at one point at the level of the plantar side of the heel. The overall centre of gravity of the body measured in this way was first described by [PERSON] in the 19 th century [2]. * Dynamic method--movement analysis, which uses camera and marker systems (e.g., Vicon system, BTS) to track body movement. The software analyses the movement of individual body segments and determines the position of the centre of gravity in different phases of movement [2; 3; 4; 5]. * Segmental weighing method, in which the mass and position of the centre of gravity of individual body parts (head, torso, limbs) are determined based on special anthropometric tables. Mathematical formulas are then used to determine the centre of gravity of the entire body [6]. The human body can assume various positions, so the _CoG_ may change its position and even be located outside the body, for example when a person is bent over and reaches for their toes [7]. In an erect human, the general _CoG_ is located at a point where the human body, when placed horizontally on a platform (equal to the length of a human body), supported at this point, balances itself. After carrying out a series of population measurements, it was assumed that the general _CoG_ is located in the midline of the body, just in front of the second sacral vertebra at an average height of ~57% of a man's height and ~55% of a woman's height. The general variation in the human population ranges between 56 and 58% body height [2; 8]. The line of gravity runs through the centre of gravity of the body, which, when viewed from the side, is located very slightly behind the heads of the femurs, and frontally runs through the centre of the sacrum and perpendicular to the ground at a point equidistant from the two heads of the femur [9; 10]. This position changes with body structure, posture, age, and gender [11; 12]. Infants have the highest general centre of gravity, which lowers in children and is lowest in adults. The location of the general _CoG_ is related to the different distribution of weight in the human body; for example, men have a more developed and muscular shoulder girdle. Women have a more developed hip belt.