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Novel Analog For Muscle DeconditioningExisting models (such as bed rest) of muscle deconditioning are cumbersome and expensive. We propose a new model utilizing a weighted suit to manipulate strength, power, or endurance (function) relative to body weight (BW). Methods: 20 subjects performed 7 occupational astronaut tasks while wearing a suit weighted with 0-120% of BW. Models of the full relationship between muscle function/BW and task completion time were developed using fractional polynomial regression and verified by the addition of pre-and postflightastronaut performance data for the same tasks. Splineregression was used to identify muscle function thresholds below which task performance was impaired. Results: Thresholds of performance decline were identified for each task. Seated egress & walk (most difficult task) showed thresholds of leg press (LP) isometric peak force/BW of 18 N/kg, LP power/BW of 18 W/kg, LP work/BW of 79 J/kg, isokineticknee extension (KE)/BW of 6 Nm/kg, and KE torque/BW of 1.9 Nm/kg.Conclusions: Laboratory manipulation of relative strength has promise as an appropriate analog for spaceflight-induced loss of muscle function, for predicting occupational task performance and establishing operationally relevant strength thresholds.
Document ID
20110008690
Acquisition Source
Johnson Space Center
Document Type
Presentation
Authors
Ploutz-Snyder, Lori (NASA Johnson Space Center Houston, TX, United States)
Ryder, Jeff (NASA Johnson Space Center Houston, TX, United States)
Buxton, Roxanne (NASA Johnson Space Center Houston, TX, United States)
Redd. Elizabeth (NASA Johnson Space Center Houston, TX, United States)
Scott-Pandorf, Melissa (NASA Johnson Space Center Houston, TX, United States)
Hackney, Kyle (NASA Johnson Space Center Houston, TX, United States)
Fiedler, James (NASA Johnson Space Center Houston, TX, United States)
Ploutz-Snyder, Robert (NASA Johnson Space Center Houston, TX, United States)
Bloomberg, Jacob (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
April 10, 2011
Subject Category
Man/System Technology And Life Support
Report/Patent Number
JSC-CN-23295
Meeting Information
Meeting: Experimental Biology conference
Location: Washington, DC
Country: United States
Start Date: April 10, 2011
Distribution Limits
Public
Copyright
Public Use Permitted.

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