Motor unit activity during stereotyped finger tasks and computer mouse work

• Published in: Journal of electromyography and kinesiology Vol. 11; no. 3; pp. 197 - 206
• Main Authors: Søgaard, K, Sjøgaard, G, Finsen, L, Olsen, H.B, Christensen, H
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2001
• Subjects: Action Potentials; Adult; Computer mouse; Computers; Contra lateral activity; Doublets; Electromyography; Female; Fingers; Humans; Mental load; Motor Neurons - physiology; Muscle activity; Muscle Contraction; Muscle Fibers, Skeletal - physiology; Muscle, Skeletal - innervation; Contra lateral activity; Doublets; Computer mouse; Mental load; Muscle activity
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/S1050-6411(00)00053-5

Motor unit (MU) activity pattern was examined in the right-hand extensor digitorum communis muscle (EDC) during standardised finger movements simulating actual computer mouse tasks. Intramuscular recordings were performed with a quadripolar needle electrode. Nine women performed four lifts of their right-hand index finger, middle finger or both as well as a number of double clicks. Additionally, the subjects performed contra lateral activity with their left-hand fingers and for three subjects recordings were also obtained during an interview with no physical activity. Besides the expected close coupling of MU activity with finger movement, activity was observed in three different situations with no physical requirements. Attention related activity was found before or after performance of the finger movement task, contra lateral activity in right EDC during left-hand finger tasks, and activity during mental activity without any finger movements involved. A relatively large number of doublet occurrences suggest they are a natural part of the activation pattern during performance of the rapid finger movement required to perform an efficient double click on the computer mouse.