title: Adaptations in physiological properties of rat motor units following 5 weeks of whole-body vibration.
abstract: The purpose of the study was to determine the effects of 5-week whole-body vibration (WBV) on contractile parameters and force-frequency relationship of functionally isolated motor units of the rat medial gastrocnemius muscle: fast fatigable (FF), fast fatigue-resistant (FR), and slow (S). Moreover, myosin heavy chain isoform content was quantified. Following WBV, the maximum tetanic force of FF units was increased by ∼25%. The twitch half-relaxation time in all types of motor units and the twitch contraction time in FR units were shortened. The twitch-to-tetanus force ratio was decreased and the force-frequency curves were shifted rightwards in S and FR units. Myosin heavy chain distribution was not changed. These findings suggest modifications of the excitation-contraction coupling towards shortening of a twitch contraction. The observed increase in force of FF units may contribute to gains in muscle dynamic strength reported following WBV treatment.
authors.affiliation: a Department of Neurobiology, University School of Physical Education, 27/39 Królowej Jadwigi, 61-871, Poznań, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Lochyński
authors.forename: Marcin
authors.initials: M
authors.lastname: Bączyk
authors.forename: Dominik
authors.initials: D
authors.lastname: Kaczmarek
authors.forename: Maria Jolanta
authors.initials: MJ
authors.lastname: Rędowicz
authors.forename: Jan
authors.initials: J
authors.lastname: Celichowski
authors.forename: Piotr
authors.initials: P
authors.lastname: Krutki
mesh_terms: D000818:Animals; D009046:Motor Neurons; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D051381:Rats; D014732:Vibration