title: Vibrografic signs of autonomous muscle tone studied in long term space missions.
abstract: Signs of resting muscle tone, assessed by cardiac driven microvibrations (MV), were studied in two cosmonauts during long term space missions on the Russian MIR station. In the 1 g environment, MV showed the typical 7-13 Hz resonance oscillations triggered by the heart beat. In 0 g, these pulsations were damped and the waveform became similar to an acceleration ballistocardiogram. If resting tone was slightly increased by extending the arm in 0 g, the resonance oscillations reappeared in most cases. By means of a simple vibromechanic analog it is demonstrated that the elastic component of muscle has to be reduced during the fully relaxed state in 0g.
authors.affiliation: University of Graz, Department of Physiology, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Gallasch
authors.forename: I B
authors.initials: IB
authors.lastname: Kozlovskaya
mesh_terms: D000337:Aerospace Medicine; D001132:Arm; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D009129:Muscle Tonus / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D013026:Space Flight; D014732:Vibration; D014893:Weightlessness