Date of Award

2009

Degree Type

Thesis

Degree Name

M.H.K.

Department

Kinesiology

First Advisor

Jakobi, Jennifer (Human Kinetics)

Keywords

Health Sciences, Human Development.

Rights

CC BY-NC-ND 4.0

Abstract

Muscle compartmentalization in the short (SBB) and long (LBB) heads of the biceps brachii (BB) might occur through spinal connections of 1a afferent feedback. Tendon vibration (TV) was used to quantify the effect of excitatory 1a afferent feedback on motor unit properties in the SBB and LBB. Eight women and 8 men (20-24years) maintained isometric elbow flexion at 15% maximum, and TV was applied (5s) in the middle of a 35s constant effort. Motor unit discharge rates (DR) were higher in men (13.99+3.12Hz) than women (12.81+3.13Hz) and in LBB (14.81+2.81Hz) compared with SBB (13.82+2.27Hz), (p<0.05). Following TV force steadiness decreased, more motor units were recruited in the SBB than LBB, but DR declined more in the LBB. Compartmentalization of SBB and LBB likely occurs through 1a afferent feedback contributing to excitatory post synaptic potentials in SBB motor neurons, but post activation depression predominates in the LBB.

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