Changes in spine height throughout 32 hours of bedrest

McGill, Stuart M.; Axler, Craig T.

doi:10.1016/s0003-9993(96)90071-4

Cited by 19 publications

(12 citation statements)

References 9 publications

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“…Mechanically this leads to a non-equilibrium state between the external load and the osmotic pressure in the disc, which results in changes in water content (McMillan et al, 1996;Pflaster et al, 1997). In vivo measurements of the signal intensity in MRI images of discs clearly show an increase in water content after a night's rest (Malko et al, 2002) and during the night disc height lost during the day is regained (McGill and Axler, 1996;Reilly et al, 1984). It has previously been found that recovery is hampered during in vitro testing of IVDs (van der Veen et al, 2005;Maclean et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Intervertebral disc recovery after dynamic or static loading in vitro: Is there a role for the endplate?

Veen

Dieën

Nadort

et al. 2007

Journal of Biomechanics

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Section: Discussionmentioning

confidence: 99%

Intervertebral disc recovery after dynamic or static loading in vitro: Is there a role for the endplate?

Veen

Dieën

Nadort

et al. 2007

Journal of Biomechanics

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“…Thornton and collaborators (29) found a decrease in spinal curvature with exposing to microgravity. Moreover, LeBlanc and coworkers (17) report that even short-duration spaceflight produces significant back muscular atrophy.Due to the high cost of research during actual microgravity, bed rest is often used as an analog of microgravity to study the anatomical and physiological changes of the spine, as well as other gravity-related functions (11,20,24). Hutchinson and coworkers (10) document that 6°head-down tilt (HDT) bed rest increases body height.…”

mentioning

confidence: 99%

“…Due to the high cost of research during actual microgravity, bed rest is often used as an analog of microgravity to study the anatomical and physiological changes of the spine, as well as other gravity-related functions (11,20,24). Hutchinson and coworkers (10) document that 6°head-down tilt (HDT) bed rest increases body height.…”

mentioning

confidence: 99%

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

Cao¹,

Kimura²,

Macias³

et al. 2005

Journal of Applied Physiology

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. Exercise within lower body negative pressure partially counteracts lumbar spine deconditioning associated with 28-day bed rest. J Appl Physiol 99: 39 -44, 2005. First published March 10, 2005; doi:10.1152/japplphysiol.01400.2004.-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 Ϯ 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 Ϯ 0.4 mm, P ϭ 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 Ͻ 0.05). In the Ex group, there were no significant increases in L 5-S1 and L4-5 disk heights. Lumbar lordosis decreased significantly by 3.3 Ϯ 1.2°d uring bed rest in the Con group (P ϭ 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. simulated microgravity; lumbar spine length; intervertebral disk height; spinal curvature; countermeasures MANY ANATOMICAL AND PHYSIOLOGICAL changes occur when the human body is exposed to microgravity. These changes include cardiovascular deconditioning, loss of exercise capacity, muscle atrophy, and bone loss. Moreover, there are several reports concerning spine deconditioning during adaptation to microgravity, such as spine lengthening (4, 28, 32), intervertebral disk alterations (15), spine curvature increase (29), and back muscle atrophy (17).Because the lumbar spine normally bears ϳ50% body weight (BW) during upright posture on Earth (14, 22, 23), this portion of the spine may be uniquely adapted to gravity. On Earth after overnight bed rest, lumbar length increases ϳ2.7 mm (15). During spaceflight, 4-to 6-cm increase of body height occurs in astronauts (4, 28, 32). Additionally, intervertebral disk volume and cross-sectional area (CSA) increase during simulated and actual microgravity (11,15). Animal experiments document disk biochemistry and degeneration during microgravity (12,25). Thornton and collaborators (29) found a decrease in spinal curvature with exposing to microgravity. Moreover, LeBlanc and coworkers (17) report that even short-duration spacefligh...

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“…It is advocated [9,[15][16][17][18][19][20] that the spinal shrinkage can be tested by a precision stadiometer to find changes in stature, in standing and/or sitting postures [17,20,21]. It is commonly established that results of stature height measurement are reliable and also valid.…”

Section: Introductionmentioning

confidence: 99%