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Predicting Fatigue for Isolated Joints While Wearing an Extra-Vehicular Mobility Unit (EMU)To work outside a space craft, humans must wear a protective suit. The required suit pressurization creates additional resistance for the wearer while performing work. How much does the suit effect work and fatigue? To answer these questions, dynamic torque was collected for the shoulder, elbow and wrist for six subjects in an Extra-vehicular Mobility Unit (EMU). In order to quantify fatigue, the subjects were to exert maximum voluntary torque for five minutes or until their maximum fell below 50% of their initial maximum for three consecutive repetitions. Using the collected torque and time data, logarithmic based functions were derived to estimate torque decay to within an absolute error of 20%. These results will be used in the development of a generalized tool for prediction of maximum available torque over time for humans using the current EMU.
Document ID
Document Type
Preprint (Draft being sent to journal)
Maida, James C. (NASA Johnson Space Center Houston, TX United States)
Gonzalez, L. Javier (Johnson Engineering Corp. United States)
Rajulu, Sudhaker (National Space Biomedical Research Inst. Houston, TX United States)
Miles, Erica (Lockheed Martin Corp. United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2001
Subject Category
Structural Mechanics
Report/Patent Number
Meeting Information
SAE Digital Human Modeling Conference(Arlington, VA)
Funding Number(s)
Distribution Limits
Public Use Permitted.

Available Downloads

NameType 20030014826.pdf STI