title: Mechanical properties and behaviour of motor units in the tibialis anterior during voluntary contractions.
abstract: The present work was carried out to analyse the properties and behaviour of Tibialis anterior motor units (MUs) during voluntary contractions in humans. A total of 528 single MU mechanical properties was recorded in 10 subjects by means of the spike-triggered averaging (STA) technique. MU recruitment thresholds and discharge frequencies were recorded during linearly increasing maximal voluntary contraction (MVC). The results indicate a mean (+/- SD) MU torque of 25.5 +/- 21.5 mN.m. and a mean time-to-peak of 45.6 +/- 13.6 ms. A comparison of the average MU twitch torque with that of the muscle allowed an estimate of about 300 MUs in the Tibialis anterior. A positive linear relationship was recorded between the MU twitch torque and the recruitment threshold. The mean minimal and maximal discharge frequencies of MUs were 8.4 +/- 3.0 Hz and 33.2 +/- 14.7 Hz, respectively. The results of the present work indicate that MU behaviour during voluntary contractions is different in the tibialis anterior and in the adductor pollicis.
authors.affiliation: Laboratory of Biology, Université Libre de Bruxelles, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Van Cutsem
authors.forename: P
authors.initials: P
authors.lastname: Feiereisen
authors.forename: J
authors.initials: J
authors.lastname: Duchateau
authors.forename: K
authors.initials: K
authors.lastname: Hainaut
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation*