title: Effect of moderate dehydration on torque, electromyography, and mechanomyography.
abstract: The purpose of the present investigation was to test the hypotheses that the mechanomyographic (MMG) signal would be affected by hydration status due to changes in the intra- and extracellular fluid content (which could affect the degree of fluid turbulence), changes in the filtering properties of the tissues between the MMG sensor and muscle, and changes in torque production that may accompany dehydration. Ten subjects (age 22.5 +/- 1.6 years) were tested for maximal isometric (MVC), submaximal isometric (25, 50, and 75%MVC), and maximal concentric isokinetic muscle strength of the biceps brachii in either a euhydrated or dehydrated state while the electromyographic (EMG) and MMG signals were recorded. Separate three-way and two-way ANOVAs indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, and MMG MPF with dehydration. The lack of dehydration effect suggests that MMG may be more reflective of the intrinsic contractile processes of a muscle fiber (torque production) or the motor control mechanisms (reflected by the EMG) than the tissues and fluids surrounding the muscle fiber.
authors.affiliation: Laboratory of Applied Physiology, University of Southern Mississippi, School of Human Performance and Recreation, Hattiesburg, Mississippi, USA. taeveto1@wsc.edu
authors.forename: Tammy K
authors.initials: TK
authors.lastname: Evetovich
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Boyd
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Drake
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Eschbach
authors.forename: Meir
authors.initials: M
authors.lastname: Magal
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Soukup
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Webster
authors.forename: Malcolm T
authors.initials: MT
authors.lastname: Whitehead
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Weir
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003681:Dehydration / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology; D019415:Torque