Search results for "Biomekaniikka"

Deep learning approach for prediction of impact peak appearance at ground reaction force signal of running activity

2020

Protruding impact peak is one of the features of vertical ground reaction force (GRF) that is related to injury risk while running. The present research is dedicated to predicting GRF impact peak appearance by setting a binary classification problem. Kinematic data, namely a number of raw signals in the sagittal plane, collected by the Vicon motion capture system (Oxford Metrics Group, UK) were employed as predictors. Therefore, the input data for the predictive model are presented as a multi-channel time series. Deep learning techniques, namely five convolutional neural network (CNN) models were applied to the binary classification analysis, based on a Multi-Layer Perceptron (MLP) classifi…

Ricci-flow based conformal mapping of the proximal femur to identify exercise loading effects.

2018

AbstractThe causal relationship between habitual loading and adaptive response in bone morphology is commonly explored by analysing the spatial distribution of mechanically relevant features. In this study, 3D distribution of features in the proximal femur of 91 female athletes (5 exercise loading groups representing habitual loading) is contrasted with 20 controls. A femur specific Ricci-flow based conformal mapping procedure was developed for establishing correspondence among the periosteal surfaces. The procedure leverages the invariance of the conformal mapping method to isometric shape differences to align surfaces in the 2D parametric domain, to produce dense correspondences across an…

Towards modern understanding of the Achilles tendon properties in human movement research

2023

The Achilles tendon (AT) is the strongest tendon in humans, yet it often suffers from injury. The mechanical properties of the AT afford efficient movement, power amplification and power attenuation during locomotor tasks. The properties and the unique structure of the AT as a common tendon for three muscles have been studied frequently in humans using in vivo methods since 1990's. As a part of the celebration of 50 years history of the International Society of Biomechanics, this paper reviews the history of the AT research focusing on its mechanical properties in humans. The questions addressed are: What are the most important mechanical properties of the Achilles tendon, how are they stud…

In vivo 3D muscle architecture quantification based on 3D freehand ultrasound and magnetic resonance imaging

2023

Muscle architecture parameters, such as the fascicle length, pennation angle, and volume, are important muscle morphology characteristics. Accurate in vivo quantification of these parameters allows to detect changes due to pathologies, interventions, and rehabilitation trainings, which ultimately impact on muscles’ force-producing capacity. In this study, we compared three-dimensional (3D) muscle architecture parameters of the tibialis anterior and gastrocnemius medialis, which were quantified by 3D freehand ultrasound (3DfUS) and a magnetic resonance imaging (MRI) technique, diffusion tensor imaging (DTI), respectively. Sixteen able-bodied subjects were recruited where seven of them receiv…

Evaluating objective measures of impairment to trunk strength and control for cross-country sit skiing

2021

AbstractIn Paralympic cross-country sit skiing, athlete classification is performed by an expert panel, so it may be affected by subjectivity. An evidence-based classification is required, in which objective measures of impairment must be identified. The purposes of this study were: (i) to evaluate the reliability of 5 trunk strength measures and 18 trunk control measures developed for the purposes of classification; (ii) to rank the objective measures, according to the largest effects on performance. Using a new testing device, 14 elite sit-skiers performed two upright seated press tests and one simulated poling test to evaluate trunk strength. They were also subjected to unpredictable bal…

Lannerangan ja lonkan ojentajalihasten aktivaatiotason arviointi emg-muutosten avulla koordinaatio- sekä voimaharjoituksissa terveillä naisilla ja mi…

1998

Käsivedon muuttujien yhteys viidenkymmenen metrin vapaauinnin aikaan : uuden anturiteknologiaan perustuvan tehomittarin testaus

2017

Johdanto. Uimari on uidessaan käytännössä lähes koko vartalollaan kosketuksissa veteen. Vesi on väliaine, joka vastustaa uimarin etenemistä ja josta voiman ja vastavoiman periaatteen mukaisesti uimaria eteenpäin vievien voimien tukipinnat tulisi löytää. Veden viskoelastinen luonne luo omat erityispiirteensä eteenpäin suuntautuvien ja vastustavien voimien välille. Tässä tutkimuksessa keskitytään vapaauinnin käsivedon muuttujiin, joiden avulla pyritään arvioimaan uimarin käsivedon eteenpäin vieviä voimia ja niiden yhteyttä uintinopeuteen. Tämän lisäksi tutkitaan anturiteknologiaan perustuvan tehomittarin reliabiliteettia ja arvioidaan validiteettia. Menetelmät. Koehenkilöinä oli kansallisen j…

Naisten keihäänheiton biomekaaninen analyysi Helsingin EM-kilpailuissa 2012

2016

Keihäänheitto on räjähtävää voimaa ja nopeutta vaativa tekninen laji. Perustekniikka on kaikilla samanlainen, mutta tekniikassa on yksilöllistä vaihtelua. Suoritus alkaa alkuvauhdilla, josta siirrytään heittoaskeleisiin. Heittoaskelten viimeinen ristiaskel on tärkeä, jotta päästään mahdollisimman hyvin vetovaiheeseen. Vetovaihe kestää vain noin 100–150 millisekuntia ja sen aikana heittäjän tulisi pystyä tekemään monimutkainen liikeketju oikea-aikaisesti ja oikeassa järjestyksessä. Keihään lähtönopeus on tärkein yksittäinen tekijä, joka vaikuttaa heiton pituuteen. Lähtönopeuteen vaikuttavia tekijöitä on paljon, eikä niistä yksikään ole osoittautunut muita merkittävämmäksi. Tämän työn tarkoit…

Neuromuscular interaction during human walking : how do changes in muscle–tendon mechanics affect the motor control of walking?

2009

Muscle-Tendon Interaction During Human Dolphin-Kick Swimming

2019

Without high impact forces, it is not clear how humans can utilize tendon elasticity during low-impact activities. The purpose of the present study was to examine the muscle-tendon behavior together with the electromyographic (EMG) activities of the vastus lateralis (VL) muscle during the human dolphin-kicking. In a swimming pool, each subject (n = 11) swam the 25 m dolphin-kicking at two different speeds (NORMAL and FAST). Surface EMGs were recorded from the VL and biceps femoris (BF) muscles. Simultaneous recordings of the knee joint angle by electro-goniometer and of the VL fascicle length by ultrasonography were used to calculate the muscle-tendon unit and tendinous length of VL(L-MTU a…