The effects of Valsalva (Val), isometric contraction (Iso), and the L-1 maneuvers (L-1) on cardiac volumes at 1 G and during 4 G were evaluated. Two-dimensional echocardiography was used to measure volumes. In the 1 G phase, eight seated male subjects performed the three maneuvers. The end-diastolic volume (EDV) decreased during VAL and L-1 (p 0.05). EDV decreased initially, but then returned to baseline with Iso. In the 4 G phase, seven male subjects experienced three 30 second 4 G epochs while performing the three maneuvers. During 4 G, 3 of 7 performing Val, 2 of 7 performing Iso, and none performing L-1 experienced peripheral light loss. EDV decreased and stabilized below baseline during the 4 Gz epoch (p 0.05). Heart rate and cardiac output increased for all maneuvers. Differences between the effects of Val, Iso, and L-1 on G-tolerance do not appear to be related to a differential ability to maintain cardiac volumes. L-1 must provide more G protection due to the isometric contraction component of the maneuver and its ability to increase blood pressure.


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    Title :

    The effect of various straining maneuvers on cardiac volumes at 1 G and during +Gz acceleration


    Additional title:

    Der Einfluß verschiedener Belastungsmanöver auf die Herzvolumina bei 1 G und bei der +Gz-Beschleunigung


    Contributors:
    Tripp, L. (author) / Jennings, T. (author) / Howell, L. (author) / Seaworth, J. (author) / Ratino, D. (author) / Goodyear, C. (author)


    Publication date :

    1990


    Size :

    7 Seiten, 22 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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