Exercise within lower body negative pressure partially counteracts lumbar spine deconditioning associated with 28-day bed rest

2005 ◽  
Vol 99 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Peihong Cao ◽  
Shinji Kimura ◽  
Brandon R. Macias ◽  
Toshiaki Ueno ◽  
Donald E. Watenpaugh ◽  
...  

Astronauts experience spine deconditioning during exposure to microgravity due to the lack of axial loads on the spine. Treadmill exercise in a lower body negative pressure (LBNP) chamber provides axial loads on the lumbar spine. We hypothesize that daily supine LBNP exercise helps counteract lumbar spine deconditioning during 28 days of microgravity simulated by bed rest. Twelve sets of healthy, identical twins underwent 6° head-down-tilt bed rest for 28 days. One subject from each set of twins was randomly assigned to the exercise (Ex) group, whereas their sibling served as a nonexercise control (Con). The Ex group exercised in supine posture within a LBNP chamber for 45 min/day, 6 days/wk. All subjects underwent magnetic resonance imaging of their lumbar spine before and at the end of bed rest. Lumbar spinal length increased 3.7 ± 0.5 mm in the Con group over 28-day bed rest, whereas, in the Ex group, lumbar spinal length increased significantly less (2.3 ± 0.4 mm, P = 0.01). All lumbar intervertebral disk heights (L5–S1, L4–5, L3–4, L2–3, and L1–2) in the Con group increased significantly over the 28-day bed rest ( P < 0.05). In the Ex group, there were no significant increases in L5–S1 and L4–5 disk heights. Lumbar lordosis decreased significantly by 3.3 ± 1.2° during bed rest in the Con group ( P = 0.02), but it did not decrease significantly in the Ex group. Our results suggest that supine LBNP treadmill exercise partially counteracts lumbar spine lengthening and deconditioning associated with simulated microgravity.

2007 ◽  
Vol 102 (6) ◽  
pp. 2274-2278 ◽  
Author(s):  
Brandon R. Macias ◽  
Peihong Cao ◽  
Donald E. Watenpaugh ◽  
Alan R. Hargens

The purpose of this study was to determine whether lower body negative pressure (LBNP) treadmill exercise maintains lumbar spinal compressive properties, curvature, and back muscle strength after 28 days of 6° head-down tilt (HDT) bed rest (BR). We hypothesize that LBNP treadmill exercise will maintain lumbar spine compressibility, lumbar lordosis and back muscle strength after 28 days of 6° HDT bed rest. Fifteen healthy identical twin pairs (14 women and 16 men) participated in this study. One identical twin was randomly assigned to the nonexercise control (Con) group, and their sibling was assigned to the exercise (Ex) group. The lumbar spine was significantly more compressible Post-BR compared with Pre-BR in the Con ( P = 0.01). Lumbar spine compressibility Post-BR was not significantly different compared with Pre-BR in the Ex group ( P = 0.89). In both the Con and Ex groups, there were no significant changes Post-BR in lumbar lordosis compared with Pre-BR. Back muscle strength significantly decreased in the Con group Post-BR ( P = 0.002), whereas in the Ex group back muscle strength was not significantly different from Pre-BR values. A significant increase in lumbar spine compressibility in the Con group suggests that spinal deconditioning to gravity occurs during 28-day bed rest. Changes in the mechanical properties of the lumbar spine may be an early indicator of lumbar intervertebral disk degeneration. Supine LBNP treadmill exercise provides axial loads to the lumbar spine and may prevent lumbar spine deconditioning associated with HDT 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 ◽  
...  

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.


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 ◽  
...  

2000 ◽  
Vol 89 (1) ◽  
pp. 218-227 ◽  
Author(s):  
Donald E. Watenpaugh ◽  
Richard E. Ballard ◽  
Suzanne M. Schneider ◽  
Stuart M. C. Lee ◽  
Andrew C. Ertl ◽  
...  

Bed rest and spaceflight reduce exercise fitness. Supine lower body negative pressure (LBNP) treadmill exercise provides integrated cardiovascular and musculoskeletal stimulation similar to that imposed by upright exercise in Earth gravity. We hypothesized that 40 min of supine exercise per day in a LBNP chamber at 1.0–1.2 body wt (58 ± 2 mmHg LBNP) maintains aerobic fitness and sprint speed during 15 days of 6° head-down bed rest (simulated microgravity). Seven male subjects underwent two such bed-rest studies in random order: one as a control study (no exercise) and one with daily supine LBNP treadmill exercise. After controlled bed-rest, time to exhaustion during an upright treadmill exercise test decreased 10%, peak oxygen consumption during the test decreased 14%, and sprint speed decreased 16% (all P < 0.05). Supine LBNP exercise during bed rest maintained all the above variables at pre-bed-rest levels. Our findings support further evaluation of LBNP exercise as a countermeasure against long-term microgravity-induced deconditioning.


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