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Foot-Ground Reaction Force During Resistance Exercise in Parabolic FlightAn interim Resistance Exercise Device (iRED) was designed to provide resistive exercise as a countermeasure to space flight-induced loss of muscle strength and endurance as well as decreased bone mineral density. The purpose of this project was to compare foot-ground reaction force during iRED exercise in normal gravity (l-g) versus micro gravity (O-g) achieved during parabolic flight. METHODS: Four subjects performed three exercises using the iRED (squat, heel raise, and deadlift) during I-g and O-g at a moderate intensity (60% of maximum strength during deadlift exercise). Foot-ground reaction force was measured in three axes (x,y,z) using a force plate, and the magnitude of the resultant force vector was calculated (r = ~X 2 + y2 + Z2 ). Range of motion (ROM) was measured using a linear encoder. Peak force (PkF) and total work (TW) were calculated using a customized computer program. Paired t-tests were used to test if significant differences (p.::::0.05) were observed between I-g and O-g exercise. RESULTS: PkF and TW measured in the resultant axis were significantly less in O-g for each of the exercises tested. During O-g, PkF was 42-46% and TW was 33- 37% of that measured during I-g. ROM and average time to complete each repetition were not different from I-g to O-g. CONCLUSIONS: When performing exercises in which body mass is a portion of the resistance during I-g, PkF and TW measured during resistive exercise were reduced approximately 60-70% during O-g. Thus, a resistive exercise device during O-g will be required to provided higher resistances to induce a similar training stimulus to that on Earth.
Document ID
20100036693
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Lee, Stuart M. C.
(Wyle Labs., Inc. Houston, TX, United States)
Cobb, Kendall
(Houston Univ.-Clear Lake Houston, TX, United States)
Loehr, James A.
(Wyle Labs., Inc. Houston, TX, United States)
Nguyen, Daniel
(Johnson Engineering Corp. Houston, TX, United States)
Schneider, Suzanne M.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2003
Subject Category
Aerospace Medicine
Report/Patent Number
JSC-CN-7571
Distribution Limits
Public
Copyright
Public Use Permitted.
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