Przeglądanie według Temat "biomechanics"

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Co-evolution of the upper limbs of early hominids and the origins of stonecraft
(Fundacja Rzeszowskiego Ośrodka Archeologicznego, 2014) Piątkowska, Katarzyna
This article discusses the subject of manipulative skills of early hominids in the context of stone toolmaking capabilities. A juxtaposition of morphological characteristics of fossilised bones with precise technological analyses, in particular studies on operational sequences (chaine operatoire) and debitage reassembly, allows us to determine which movement sequences were necessary to make tools. Analyses of the upper extremities of hominini are based on the comparison with well-studied principles which govern the functioning of the upper limb of Homo sapiens. Detailing the biomechanics of lithic reduction (stone knapping) by Homo sapiens enabled us to establish the required sequence of movements. This was compared with technological analyses of Lower Paleolithic materials. Based on biomechanical and technological studies we arrived at a number of characteristics in the morphological structure of upper limbs which could make it easier to specify which species had been capable of making tools. The set of characteristics was compared with data from analyses of fossilised bones of early hominids.
Measurement of Angular Parameters and Velocities of the Upper Limb Segments in Tennis Using Inertial Motion Sensors for the Purposes of the Didactic Process
(Wydawnictwo Uniwersytetu Rzeszowskiego, 2019) Wołoszyn, Filip
The aim of the study is to show differences in accurate and missed forehand and backhand strokes in tennis, as a feedback for coaches, teachers and players. The main assumptions of the study are to show the values of angular parameters and velocity, as well as to analyse every phase of a stroke. The priority in the study is to show how the abovementioned parameters affect the accuracy and velocity of forehand and backhand strokes. Material and research methods: A professional tennis player was tested using the individual case method and kinematic analysis. The motion capture system (MCS) was used for research purposes using inertial motion sensors. Results: Strokes were analysed to demonstrate the angular parameters and velocities of selected upper limb segments. Three upper limb segments were taken into account, i.e. the right hand, the right forearm and the right shoulder. The results of the angles and velocities achieved by individual segments were analysed in three axes of the body: X, Y, Z. The results concern the beginning of the acceleration phase, the end of the acceleration phase, i.e. the moment of impact, and the final, follow-through phase. Conclusion: The results show that a stroke can be accurate despite a significant change in angle and velocity. This situation applies to both forehand and backhand strokes.
Upper limb analysis measured by inertial measurement unit tool: a case report
(Wydawnictwo Uniwersytetu Rzeszowskiego, 2019) Wołoszyn, Filip; Czmil, Anna
Introduction. This article reports differences in accurate and inaccurate forehand and backhand strokes in tennis. The tests were carried out on a professional tennis player. The duration of a stroke, the heights of the individual segments of the right upper limb and differences in the heights of the segments at the beginning and at the end of every phase of stroke were examined. Aim. The major aim of the work was to expose upper limb disparity in stokes. Description of the case report. The research tool was inertial motion sensors (IMS) based on an accelerometer, a gyroscope and a magnetometer. A professional tennis player was examined using the individual case method and kinematic analysis. Results. The analysis concerned the average time to perform forehand and backhand strokes during all phases of the stroke, i.e. preparation, acceleration and follow-through phases. The average heights of the individual upper limb segments during a stroke were also taken into account. The results of the study are meant to show how the movement of the upper limb affects the accuracy and velocity of a stroke. Conclusion. The movements of individual segments in some accurate strokes were similar to those in inaccurate strokes.