Motor unit recruitment in the trapezius muscle with special reference to coarse arm movements.
Artikel i vetenskaplig tidskrift, 2001

Chronic shoulder pain is common in a variety of occupations. The "Cinderella hypothesis" suggests that the pain originates from damaged type I muscle fibres driven into degenerative processes as a result of too long activation and too short recovery time. The main purpose of this study was to investigate if the same motor units are active during all phases of coarse arm movements. Eight healthy volunteers participated in the study. Intramuscular electromyographic signals were picked up with a four-lead fine wire electrode, during a unilateral straight arm movement. The movement started with either (part 1) an abduction or a flexion, then (2) a movement in the horizontal plane from the sagittal to the frontal plane or vice versa, and finally (3) an adduction or an extension to the start position. The movement cycle was performed in three different speeds, slow, medium, and high, with one, two or five cycles per 20 s, respectively. On an average, the motor unit action potentials (MUAPs) of 6 motor units (range, 1-15) were identified per trail. In total 94% of the MUAP trains that were identified showed firings in all 3 parts of the movements. The findings support the Cinderella hypothesis, although there is a need to further investigate the temporal pattern of long-term motor unit activity.

Adult

Electromyography

Recruitment

Movement

Skeletal

physiology

Female

Neurophysiological

Muscle

Action Potentials

physiology

physiology

Humans

Arm

Motor Neurons

Shoulder

Muscle Fibers

innervation

Male

Skeletal

physiology

Författare

Mikael Forsman

Institutionen för människa tekniksystem

L Birch

Qiuxia Zhang

Göteborgs universitet

Roland Kadefors

Göteborgs universitet

Journal of Electromyography and Kinesiology

1050-6411 (ISSN)

Vol. 11 207-16

Ämneskategorier

Ortopedi

PubMed

11335151