Task Progress:
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The data collected in this study indicate that ventilatory threshold can be accurately determined in a subject cohort with similar physical characteristics to NASA crewmembers. As VT1 is a more reliable indicator of endurance performance than VO2max, in addition to being more sensitive to training adaptations and deconditioning, NASA should focus on establishing methods to accurately identify VT1 in crewmembers and not VO2max. Although these data indicate a tendency for VT1 to be underestimated when metabolic data is progressively truncated from the point of VO2max and identified by graph visualization, more than 60% of all subjects were still within a 1MET (metabolic equivalent) (5.3-10.9% VO2max) error when data up to 70% VO2max was used. We propose that a submaximal exercise test that requires the individual to reach exercise intensities no greater than 70% of the VO2max would be preferred in order to minimize crew inconvenience and the potential risk of an adverse event during spaceflight missions. The data we have collected and analyzed so far indicates that exercise intensities of 60-70% VO2max will be sufficient for most, if not all, crewmembers when attempting to identify VT during a submaximal exercise test.
We also manufactured an algorithm for automated detection of VT during a graded exercise test. At the time of this task book report submission, our investigative team are still optimizing the algorithm to analyze truncated data sets as we did with visual identification. We anticipate that the percentage of subjects within a 1MET error will be substantially greater when data up to 70% VO2max is used and VT1 is identified using our automated algorithm. Unfortunately, we were unable to complete this part of the analysis as funding for this project expired before we had finished collecting data.
Future work includes determining the minimum amount of metabolic data required to accurately identify VT1 within a 1MET error using our automated algorithm, and also optimizing the computer-generated algorithm to monitor real-time changes in V-slope for the submaximal identification of VT1. To achieve this, a graduate student in the Department of Health and Human Performance (Mr. Patrick Howell) will work on optimizing the algorithm part of this project as an MS research thesis. Mr. Howell will complete this project under the supervision of Drs. Simpson and Paloski and a copy of his MS thesis and any publications that arise from this project will be sent to NASA when they are made available.
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Abstracts for Journals and Proceedings
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Simpson RJ, Ploutz-Snyder L, O'Connor DP, Ivkovic V, Wickwire PJ, McFarlin BK, Paloski WH. "Development of a submaximal exercise protocol to identify the ventilatory threshold in astronauts." 18th IAA Humans in Space Symposium, Houston, TX, April 11-15, 2011. 18th IAA Humans in Space Symposium, Houston, TX, April 11-15, 2011. , Apr-2011
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Abstracts for Journals and Proceedings
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Simpson RJ, Ploutz-Snyder L, Wickwire PJ, Howell PT, O'Connor DP, Paloski WH. "Development of a submaximal exercise protocol to identify the ventilatory threshold in astronauts." 2012 NASA Human Research Program Investigators’ Workshop, Houston, TX, February 14-16, 2012. 2012 NASA Human Research Program Investigators’ Workshop, Houston, TX, February 14-16, 2012. , Feb-2012
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