Year: 2015
Type: dissertation
Abstract: Mathematical relationships have long been used to describe many aspects of muscle\nfunction such as the relationship between muscle force and muscle length, muscle force\nand velocity of contraction or the degree of muscle activation during a contraction.\nDuring this work various mathematical expressions have been employed in order to\ngain an insight into different aspects of muscle activity.\nThe first part of the work examined whether performing a strength protocol on a\ndynamometer can lead to an increase in eccentric strength output as well as in the\nneuromuscular activation of the quadriceps group of muscles that appears inhibited\nduring slow concentric and fast eccentric contractions. Neuromuscular activation was\nmodelled via a three-parameter sigmoid function that was also tested for robustness\nto perturbations in the maximum activation values.\nDuring the second part of the study the "functional" hamstrings to quadriceps ratio\nH:Qfun was expressed as a function of two variables i.e., angular velocity and joint\nangle. Initially nine-parameter torque-angular velocity-angle profiles were obtained\nfor the knee extensors and flexors from a group of participants. A theoretical 17-\nparameter H:Qfun function was then derived for each dataset. Subsequently, a simpler,\n6-parameter function was derived, RE = aexp(bωn + cθm)-dω1/2θ2 that best reproduced\nthe original 17-parameter fit.\nFinally, a six-segment subject specific torque-driven model of the Snatch lift was developed\nin order to investigate the optimal mechanics of the lift. The model simulated\nthe lift from its initiation until the end of the second pull when the feet of the athlete\nmomentarily leave the platform. The six-segment model comprised of foot, shank,\nthigh, torso (head + trunk), arm and forearm segments with torque generators at the\nankle, knee, hip and shoulder joints respectively. The torque profiles were obtained\nusing an isokinetic dynamometer.
Author: Dimitrios Voukelatos
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2547649310