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Prediction of Changes in Orthostatic Tolerance after Head down Bed Rest With and Without Artificial gravity Training
Author(s) -
Evans Joyce McClendon,
Meng Martha,
Patwardhan Abjihit,
Stenger Michael,
Feiveson Alan,
Knapp Charles
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.1035.2
Subject(s) - bed rest , deconditioning , orthostatic vital signs , medicine , blood pressure , spaceflight , heart rate , baroreflex , cardiology , physical medicine and rehabilitation , engineering , aerospace engineering
In a recent study to evaluate the potential for artificial gravity (AG) to counteract spaceflight‐induced cardiovascular deconditioning, 8 men received a daily, one hour dose of AG (2.5 Gz ) while 7 underwent no countermeasure, during 21 days of head down bed rest (HDBR). Results After bed rest, AG‐treated subjects demonstrated greater orthostatic tolerance (OT) than control subjects, p = 0.012 (Stenger, 2008). Variables recorded during HDBR days were then analyzed to develop a model to predict OT before return to gravity. The variables evaluated represent control aspects of heart rate, blood pressure, spontaneous baroreflex activity, and breathing activity. From 16 available variables, 120 combinations were used to build a two variable model. The combination of high frequency spectral power of systolic blood pressure and mean blood pressure correctly classified subjects as trained or untrained 93% of the time. Predictive potential of this classifier was verified by bootstrap analysis. Conclusions Our data support the hypothesis that AG treatment lessens cardiovascular deconditioning in bed rested men. In addition, differences in AG treated and control subjects can be discriminated by a combination of variables related to regulation of blood pressure. This same combination of variables may be able to predict OT upon return from space . Supported by NASA AG‐Bed Rest Project (IMAG Pilot Study).