Mario Kasović

Dynamics stability in landing with ACL deficient knee joint

The purpose of this research was to determine the effect of the controlled landing tests in dynamics stabilities of ACL deficient knee pre- and post reconstruction. The test protocol included experimental and control groups. The experimental group included examines with ACL deficient knee while control group consisted of healthy examines. The protocol consisted of following testing phases: 1. testing of the knee joint muscle power (execution of the maximum voluntary contraction during which the myoelectric signals were collected) and 2. testing of the knee joint dynamic stability (execution of the test with one-legged (landings) from the 40 cm and 20 cm high bench, during which the kinematic and kinetic parameters were collected). Following variables were studied: kinematic (valgus and varus, inner and outer rotation and angle of the flexion and extension in the knee joint), ground reaction force and EMG signals of the four main muscle of lower extremity have been measured during execution of the maximum static contraction lasting for 10 seconds. The protocol consisted of two testing period time pre- and post reconstruction of ACL. Statistically significant difference between groups in the first measurement as well as between injured and healthy knee was observed. That was the case especially in kinematical parameters (in inner and outer rotation angle as well as valgus-varus movement). Generally, a change in landing dynamics of the injured knee was observed. The differences are reduced following the reconstruction, and that is especially the case in examinees that underwent proprioceptive treatment during rehabilitation. The test could be applicable as an indicator of readiness of athletes to sustain training workload as well as a predictor of injury occurrence in healthy people.

Data mining time series of human locomotion data based on functional approximation

In many of medical applications specially one considering time sequence data like data describing human gait, searching through large, unstructured databases based on sample sequences is often desirable. Such similarity-based retrieval has attracted a great deal of attention in recent years. Although several different approaches have appeared, most are not specialized for the problem of human locomotion. This paper gives an overview of one proposed approach how to efficiency process human gait by using Fourier’s series approximation, genetic algorithms for coefficients corrections and Spectral Signatures as data mining method. This paper shows how these methods fit into a general context of signature extraction and disorder recognition in the human gait case.

The influence of ski helmets on sound perception and sound localisation on the ski slope

OBJECTIVES The aim of the study was to investigate whether a ski helmet interferes with the sound localization and the time of sound perception in the frontal plane. MATERIAL AND METHODS Twenty-three participants (age 30.7±10.2) were tested on the slope in 2 conditions, with and without wearing the ski helmet, by 6 different spatially distributed sound stimuli per each condition. Each of the subjects had to react when hearing the sound as soon as possible and to signalize the correct side of the sound arrival. RESULTS The results showed a significant difference in the ability to localize the specific ski sounds; 72.5±15.6% of correct answers without a helmet vs. 61.3±16.2% with a helmet (p < 0.01). However, the performance on this test did not depend on whether they were used to wearing a helmet (p = 0.89). In identifying the timing, at which the sound was firstly perceived, the results were also in favor of the subjects not wearing a helmet. The subjects reported hearing the ski sound clues at 73.4±5.56 m without a helmet vs. 60.29±6.34 m with a helmet (p < 0.001). In that case the results did depend on previously used helmets (p < 0.05), meaning that that regular usage of helmets might help to diminish the attenuation of the sound identification that occurs because of the helmets. CONCLUSIONS Ski helmets might limit the ability of a skier to localize the direction of the sounds of danger and might interfere with the moment, in which the sound is firstly heard.

On the construction of 3D scanner : implementation of multiple phase shift method

Various 3D reconstructions principles and systems are surely among very popular tools for human movement analyses. This work has focused on projection of multiple phase shifted (MPS) light patterns and reveals straightforward approach to unwrap the so called absolute phase. The simplicity of proposed idea should warrant easy implementation among researches from various fields of expertise, including biomechanics too.

The study of muscle fatigue effect on dynamic stability in knee joint

Over the past decade, there has been an increase in sports related injuries, particularly to the lower limbs. Injuries of the knee have been the commonest, and have the greatest potential to cause both short term and long term disability. The purpose of this research was to determine the effect of the lower extremity muscle fatigue on the proprioceptive sensitivity of the motor control in knee joint. This research showed a significant influence of the fatigue on the proprioceptive sensitivity and the motor control in knee joint.

NEW LABORATORY TEST FOR DYNAMIC STABILITY IN ACL DEFICIENT KNEE JOINT

Anterior cruciate ligament (ACL) injuries are common in sports. Knee injuries are the most common, and have the greatest potential to cause both short term and long term disability. Dynamic stability of the knee during such activities is determined by the balance of muscle strength, lower extremity muscle fatigue, ligament function, joint structures contact, and ground reaction forces applied to the leg. The purpose of this research was to determine the effect of the controlled landing tests in dynamic stability. Optoelectronic system BTS ELITE, offering integration of kinematics data with the external signals of force platforms and EMG devices, was used for experiments. The developed test protocol could be applicable as an indicator of readiness of athletes to sustain training workload as well as a predictor of injury occurrence in healthy people.