Year: 1993
Type: dissertation
Abstract: Multisegmental skills, such as throwing, kicking and striking with an implement are sometimes characterized by the common objective of projecting a missile a large distance.When performed successfblly, these skills demonstrate similar patterns of motion.Kinematic studies have shown a proximal to distal sequencing of segmental motion, with the velocity of the most distal segment peaking higher and later than that of the more proximal segments.The observed pattern of motion has been accounted for by i) the nature of the segmental linkage, and ii) the mechanical properties of the muscles contributing to the motion.The first objective of this thesis was to determine the role of muscle in producing the observed behaviour of the system, including the influence of proximal antagonism late in the throw.The second objective was to determine the sensitivity of performance to changes in the mechanical properties of muscle.An understanding of the way in which muscles influence the manner in which linked segments interact is beneficial in terms of maximizing a desired output.A computer model was used to simulate planar overarm throwing.The model comprised three linked segments and six single equivalent, Hill-based muscle models providing agonistic and antagonistic influence at each joint (shoulder, elbow and wrist).A forward dynamics approach was used to determine the kinematics of each throw from a set of initial conditions.The success of a throw was evaluated by the horizontal distance the ball was projected fkom its position in the hand at the time of release.Throws which resulted in greater projectile distances were associated with a large increase in energy of the most distal segment prior to release of the ball.This increase in energy was achieved by optimal levels of work done by the shoulder and elbow agonists.The greatest percentage of total work was done by the shoulder agonist.In addition, there was a passive transfer of energy across the wrist joint by means of joint force power.Optimal timing and sequencing of onset of activation of all muscles was necessary to bring ... lll
Source: Summit (Simon Fraser University)
Author: Mary Ann Edmondstone
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2287583687