###### Abstract
Combat sports impose additional constraints on kinematic sensors (KS) use, which is arguably one of the reasons for the small number of studies applying KS in this field. Just 2.8% of the 286 studies in the review published by [PERSON] et al. [26] featured combat sports. High acceleration levels, rapid and ballistic movements, multiple rotations of the employed segments of the kinetic chain, all of which are common to combat sports, are eliminating factors for most available sensors [3; 15]. Bearing in mind that soft tissue is affected by the location and type of unit attachment, as well as the motor task and subject [26], the complexity of the topic becomes even more obvious. Previous research in combat sport, focusing on different performance features, shows the diversity of device properties with the operating range of an accelerometer between \(\pm 3\) g and \(\pm 2000\) g; a gyroscope from 1000 deg to 4000 deg; and a sampling frequency of up to 5000 Hz. Different studies employed diverse models of sensor positioning, either applying one measuring device or using a full-body model [3]. The objective here was to propose a particular reference body point that might provide the explanatory data. Additionally, sensor-to-segment axis alignment is a critical feature that should be considered when predicting joint kinematics with inertial sensors [28]. However, obtaining such data is possible only if the positioning of the device has no impact on its output [3]. Put differently, kinematic quantities at the given body attachment location must not exceed the dynamic ranges of the device. This also means that the chosen location has to meet the criteria for secure attachment. After reviewing different types of motion capture in combat sport, [PERSON] et al. [29] concluded that using marker-less estimation of motion involving upper and lower limbs is a \"challenging task\", especially emphasising the usage of a single computing unit in the utilisation, control and processing of more than one sensor concurrently. For this reason, this present study proposes a novel approach as a possible substitute for the common optical motion capture procedures, as well as for the previous solutions in sensor application. The approach is based on the application of sensors to specific chosen points on an athlete's body, testing the kinematic and temporal parameters with carefully designed tests [25; 30]. Such an approach allows for in-depth analysis of technique execution in conditions the same or similar to training and competition and in an affordable and easy-to-use way. These types of data are valuable feedback for elite karate athletes, given that each fighter at the highest level adds their own signature to the technique performance [31; 32]. An analysis of exceptional individuals can contribute to a better understanding of the basis of their success [33]. Knowing that at high levels of mastery, technique improvement is a difficult and delicate job, reliable and valid key data obtained in selected phases of execution have specific value. Speaking from the standpoint of an individual approach, in-depth analysis of elite karate competitors should focus on the critical moments in technique execution. Although the authors do not oppose the significance of impact--indeed, it has been found to be the most important phase--there is a clear necessity to investigate what happens at the very beginning of punch execution. The isolated phases preceding impact can be considered developmental in terms of the progressive increase in kinematic quantities [30]. It is reasonable to expect that possible deviations in each (i.e., initial, developmental) phase of performance affect the final outcome and the quality of the performed technique. Ultimately, it is this that determines the difference between whether a punch will be scored or not.