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|Title: ||Mathematical description of in-vivo muscle function|
|Authors: ||Voukelatos, Dimitrios|
|Keywords: ||Muscle function|
|Issue Date: ||2015|
|Publisher: ||© Dimitrios Voukelatos|
|Abstract: ||Mathematical relationships have long been used to describe many aspects of muscle
function such as the relationship between muscle force and muscle length, muscle force
and velocity of contraction or the degree of muscle activation during a contraction.
During this work various mathematical expressions have been employed in order to
gain an insight into different aspects of muscle activity.
The first part of the work examined whether performing a strength protocol on a
dynamometer can lead to an increase in eccentric strength output as well as in the
neuromuscular activation of the quadriceps group of muscles that appears inhibited
during slow concentric and fast eccentric contractions. Neuromuscular activation was
modelled via a three-parameter sigmoid function that was also tested for robustness
to perturbations in the maximum activation values.
During the second part of the study the "functional" hamstrings to quadriceps ratio
H:Qfun was expressed as a function of two variables i.e., angular velocity and joint
angle. Initially nine-parameter torque-angular velocity-angle profiles were obtained
for the knee extensors and flexors from a group of participants. A theoretical 17-
parameter H:Qfun function was then derived for each dataset. Subsequently, a simpler,
6-parameter function was derived, RE = aexp(bωn + cθm)-dω1/2θ2 that best reproduced
the original 17-parameter fit.
Finally, a six-segment subject specific torque-driven model of the Snatch lift was developed
in order to investigate the optimal mechanics of the lift. The model simulated
the lift from its initiation until the end of the second pull when the feet of the athlete
momentarily leave the platform. The six-segment model comprised of foot, shank,
thigh, torso (head + trunk), arm and forearm segments with torque generators at the
ankle, knee, hip and shoulder joints respectively. The torque profiles were obtained
using an isokinetic dynamometer.|
|Description: ||A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.|
|Appears in Collections:||PhD Theses (Sport, Exercise and Health Sciences)|
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