Date of Award

1995

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Science, Technology and Engineering

First Advisor

Dr Paul Sacco

Second Advisor

Dr Gary Thickbroom

Third Advisor

Dr Amanda Blackmore

Abstract

The objective of this study was to note the time course changes for up to 28 days on the motor control properties of biceps brachii muscle following a bout of eccentric exercise. Eight subjects (5 male, 25-40 years of age) performed 35 maximal voluntary eccentric contractions with the non-preferred arm of the elbow flexors through 130° of extension of 90°s-1. Voluntary electromyographic (EMG) activity and motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) were recorded via surface electrodes placed over the belly of the biceps brachii muscle. Maximal isometric strength was measured at 90° elbow flexion. A simple elbow flexion/extension tracking task was used to assist visuomotor co-ordination. Subjects displayed greatest strength loss at I day (of control measures) which recovered by 21 days post-exercise. Impairment in the skilled tracking task was noticeable within hours following the exercise, and was greatest 1 day post exercise, but returned to control levels by 3 days. There were no changes in the threshold level of MEP responses to TMS but maximal MEP amplitudes increased on average (although responses were variable). No changes were observed in the EMG activity following exercise. The changes in the motor performance and corticomotor excitability occur following eccentric exercise which may be related to alterations in the pattern of afferent feedback from weakened and/or painful muscles. The implications from this suggest that coaches need to be sympathetic to the needs of the athlete when balancing physical training with skill training/development

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