Lower body negative pressure exercise plus brief postexercise lower body negative pressure improve post-bed rest orthostatic tolerance

2007 ◽  
Vol 103 (6) ◽  
pp. 1964-1972 ◽  
Author(s):  
Donald E. Watenpaugh ◽  
Deborah D. O'Leary ◽  
Suzanne M. Schneider ◽  
Stuart M. C. Lee ◽  
Brandon R. Macias ◽  
...  

Orthostatic intolerance follows actual weightlessness and weightlessness simulated by bed rest. Orthostasis immediately after acute exercise imposes greater cardiovascular stress than orthostasis without prior exercise. We hypothesized that 5 min/day of simulated orthostasis [supine lower body negative pressure (LBNP)] immediately following LBNP exercise maintains orthostatic tolerance during bed rest. Identical twins (14 women, 16 men) underwent 30 days of 6° head-down tilt bed rest. One of each pair was randomly selected as a control, and their sibling performed 40 min/day of treadmill exercise while supine in 53 mmHg (SD 4) [7.05 kPa (SD 0.50)] LBNP. LBNP continued for 5 min after exercise stopped. Head-up tilt at 60° plus graded LBNP assessed orthostatic tolerance before and after bed rest. Hemodynamic measurements accompanied these tests. Bed rest decreased orthostatic tolerance time to a greater extent in control [34% (SD 10)] than in countermeasure subjects [13% (SD 20); P < 0.004]. Controls exhibited cardiac stroke volume reduction and relative cardioacceleration typically seen after bed rest, yet no such changes occurred in the countermeasure group. These findings demonstrate that 40 min/day of supine LBNP treadmill exercise followed immediately by 5 min of resting LBNP attenuates, but does not fully prevent, the orthostatic intolerance associated with 30 days of bed rest. We speculate that longer postexercise LBNP may improve results. Together with our earlier related studies, these ground-based results support spaceflight evaluation of postexercise orthostatic stress as a time-efficient countermeasure against postflight orthostatic intolerance.

2020 ◽  
Vol 4 (2) ◽  
pp. 040-048
Author(s):  
Wang Linjie ◽  
Li Zhili ◽  
Tan Cheng ◽  
Wang Huijuan ◽  
Zhou Xiangjie ◽  
...  

Introduction: Alternatively using gradient lower-body negative pressure (LBNP) and ergometer exercise (LBNP + ergo) under a flight schedule framework was explored to detect its orthostatic capacity maintenance effects in female subjects after 15 days of -6° head-down bed rest (HDBR). Methods: Twenty-two female university students were divided into a control group (n = 8), an LBNP group (n = 7), and an LBNP + ergo group (n = 7). Ergometer exercise consisted of an interval exercise protocol with 2 min intervals alternating between 41% and 70% VO2max. Gradient LBNP was decompressed in 10 mm Hg intervals to -40 mmHg every 5 min. intermittent ergometer exercise and LBNP were alternatively performed. Tilt test was performed 2 days before HDBR (R-2), on the day of HDBR termination (R+1), and 5 days after HDBR (R+5). Results: Fifty percent of the participants (11/22) did not pass the tilt test on R+1. The orthostatic tolerance time decreased from 20 to 16.1 ± 2.1 min in the control group, to 10.0 ± 2.7 min in the LBNP group (p = 0.01) and to 16.3 ± 2.0 min in the LBNP + ergo group. The HRs and BPs were at similar level among three groups during tilt test on different test days. Compared with the control group, the LBNP + ergo group had higher SV and CO percentage changes at R+1(p < 0.023) and R+5 (p < 0.00001) during the tilt test. Conclusion: LBNP combined with ergometer exercises fails to prevent orthostatic intolerance but it induced some positive hemodynamic changes during tilt test after 15 days HDBR.


1993 ◽  
Vol 74 (1) ◽  
pp. 286-292 ◽  
Author(s):  
F. M. Melchior ◽  
S. M. Fortney

Increased leg compliance (LC) has been proposed as a mechanism for orthostatic intolerance after spaceflight or bed rest. Using venous occlusion plethysmography with mercury-in-Silastic strain gauge, we evaluated LC before, during, and after a 13-day head-down (-6 degrees) bed rest in 10 men. LC was measured by the relationship between the increased calf areas (in cm2) at thigh cuff occlusions of 20, 30, 50, 70, and 80 mmHg. Orthostatic tolerance was evaluated by a presyncopal-limited lower body negative pressure test (PSL-LBNP) before and after bed rest. The 10 subjects were divided into TOL (n = 5) and INT (n = 5) groups for which the orthostatic tolerance was similar and lower after bed rest, respectively. For TOL (INT) before bed rest, calf area increases were 2.2 +/- 0.5 (SE) (1.3 +/- 0.4), 3.5 +/- 0.7 (2.3 +/- 0.5), 5.0 +/- 0.9 (3.5 +/- 0.6), 5.6 +/- 0.9 (4.4 +/- 0.6), and 6.4 +/- 1.1 (4.7 +/- 0.6) cm2 for thigh occlusion pressures of 20, 30, 50, 70, and 80 mmHg, respectively. Neither for INT nor for TOL were these results significantly changed by bed rest. These results suggest that other mechanisms than increased LC have to be taken into account to explain the decreased orthostatic tolerance induced by this 13-day bed rest.


2005 ◽  
Vol 37 (Supplement) ◽  
pp. S36
Author(s):  
Stuart M.C. Lee ◽  
Suzanne M. Schneider ◽  
Donald E. Watenpaugh ◽  
Wanda L. Boda ◽  
Brandon R. Macias ◽  
...  

Bone ◽  
2007 ◽  
Vol 40 (2) ◽  
pp. 529-537 ◽  
Author(s):  
Sara R. Zwart ◽  
Alan R. Hargens ◽  
Stuart M.C. Lee ◽  
Brandon R. Macias ◽  
Donald E. Watenpaugh ◽  
...  

2016 ◽  
Vol 4 (15) ◽  
pp. e12892 ◽  
Author(s):  
Suzanne M. Schneider ◽  
Stuart M. C. Lee ◽  
Alan H. Feiveson ◽  
Donald E. Watenpaugh ◽  
Brandon R. Macias ◽  
...  

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S36 ◽  
Author(s):  
Stuart M.C. Lee ◽  
Suzanne M. Schneider ◽  
Donald E. Watenpaugh ◽  
Wanda L. Boda ◽  
Brandon R. Macias ◽  
...  

Author(s):  
Karen E. Etter ◽  
M. Keith Sharp

Postflight orthostatic intolerance (POI) afflicts a significant fraction of male astronauts and nearly all female astronauts when they first stand on Earth after spaceflight. Symptoms include dizziness and fainting, which can impact their abilities to perform critical tasks during the post-landing period. On the Moon or Mars, poor performance or accidents resulting from POI may have potentially catastrophic consequences due to the more hazardous conditions and lack of medical facilities. In addition, the long duration flights necessary to reach Mars may elicit adaptations that increase the risk of POI. Of the many factors that may influence POI, one of the few that may explain the gradual decline in arterial blood pressure experienced by many subjects during stand tests is the loss of blood volume by capillary filtration. Previous simulations suggest that elevated capillary filtration rates distinguish nonfinishers from finishers of stand tests [1, 2]. In this investigation, further computer modeling was undertaken to compare modeled orthostatic response to that of volunteers during graded orthostatic stress (GOS) involving head up tilt (HUT) and lower body negative pressure (LBNP), which reliably produces presyncope and is a candidate training countermeasure for preventing POI.


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