From the international space station to the clinic: how prolonged unloading may disrupt lumbar spine stability

Bailey, Jeannie F.; Miller, Stephanie; Khieu, Kristine; O’Neill, Conor; Healey, Robert; Coughlin, Dezba; Sayson, Jojo V.; Chang, Douglas G.; Hargens, Alan R.; Lotz, Jeffrey C.

doi:10.1016/j.spinee.2017.08.261

Cited by 105 publications

(123 citation statements)

References 57 publications

(63 reference statements)

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“…(15,21) Preflight spine curvature was used at all time points except immediately postflight, where we reduced lumbar lordosis by 11%. (22) Trunk muscle cross-sectional area and position were determined from CT scans or calculated from regression analyses of anthropometric relations. The individual musculoskeletal models were solved using an inverse dynamics based static optimization with a cost function that minimized the sum of cubed muscle activation.…”

Section: Subject-specific Musculoskeletal Modeling For Spine Loading mentioning

confidence: 99%

Effects of Long-Duration Spaceflight on Vertebral Strength and Risk of Spine Fracture

Burkhart

Allaire

Anderson

et al. 2019

Journal of Bone and Mineral Research

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Although the negative impact of long-duration spaceflight on spine BMD has been reported, its impact on vertebral strength and risk of vertebral fracture remains unknown. This study examined 17 crewmembers with long-duration service on the International Space Station in whom computed tomography (CT) scans of the lumbar spine (L 1 and L 2 ) were collected preflight, immediately postflight and 1 to 4 years after return to Earth. We assessed vertebral strength via CT-based finite element analysis (CT-FEA) and spinal loading during different activities via subject-specific musculoskeletal models. Six months of spaceflight reduced vertebral strength by 6.1% (−2.3%, −8.7%) (median [interquartile range]) compared to preflight (p < 0.05), with 65% of subjects experiencing deficits of greater than 5%, and strengths were not recovered up to 4 years after the mission. This decline in vertebral strength exceeded (p < 0.05) the 2.2% (−1.3%, −6.0%) decline in lumbar spine DXA-BMD. Further, the subject-specific changes in vertebral strength were not correlated with the changes in DXA-BMD. Although spinal loading increased slightly postflight, the ratio of vertebral compressive load to vertebral strength for typical daily activities remained well below a value of 1.0, indicating a low risk of vertebral fracture despite the loss in vertebral strength. However, for more strenuous activity, the postflight load-to-strength ratios ranged from 0.3 to 0.7, indicating a moderate risk of vertebral fracture in some individuals. Our findings suggest persistent deficits in vertebral strength following long-duration spaceflight, and although risk of vertebral fracture remains low for typical activities, the risk of vertebral fracture is notable in some crewmembers for strenuous exercise requiring maximal effort.

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Section: Subject-specific Musculoskeletal Modeling For Spine Loading mentioning

confidence: 99%

Effects of Long-Duration Spaceflight on Vertebral Strength and Risk of Spine Fracture

Burkhart

Allaire

Anderson

et al. 2019

Journal of Bone and Mineral Research

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“…It has been speculated that swelling of the intervertebral disks due to unloading is the underlying cause of LBP in astronauts ( Sayson and Hargens, 2008 ). However, recent reports cast doubt on this, suggesting that rather than disk swelling, aberrant patterns in spinal stabilization mechanisms may be the main reason for pain ( Chang et al, 2016 ; Bailey et al, 2018 ). Functional spinal stabilization is essential for spinal health, and is guaranteed by spinal motor control ( Panjabi, 1992a ; Cholewicki et al, 2000 ).…”

Section: Introductionmentioning

confidence: 99%

Microgravity and Hypergravity Induced by Parabolic Flight Differently Affect Lumbar Spinal Stiffness

Swanenburg¹,

Langenfeld²,

Easthope

et al. 2020

Front. Physiol.

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The objective of this study was to determine the response of the lumbar spinal motor control in different gravitational conditions. This was accomplished by measuring indicators of lumbar motor control, specifically lumbar spinal stiffness, activity of lumbar extensor and flexor muscles and lumbar curvature, in hypergravity and microgravity during parabolic flights. Three female and five male subjects participated in this study. The mean age was 35.5 years (standard deviation: 8.5 years). Spinal stiffness of the L3 vertebra was measured using impulse response; activity of the erector spinae, multifidi, transversus abdominis, and psoas muscles was recorded using surface electromyography; and lumbar curvature was measured using distance sensors mounted on the back-plate of a full-body harness. An effect of gravity condition on spinal stiffness, activity of all muscles assessed and lumbar curvature ( p ’s < 0.007) was observed (Friedman tests). Post hoc analysis showed a significant reduction in stiffness during hypergravity ( p < 0.001) and an increase in stiffness during microgravity ( p < 0.001). Activity in all muscles significantly increased during hypergravity ( p ’s < 0.001). During microgravity, the multifidi ( p < 0.002) and transversus abdominis ( p < 0.001) increased significantly in muscle activity while no significant difference was found for the psoas ( p = 0.850) and erector spinae muscles ( p = 0.813). Lumbar curvature flattened in hypergravity as well as microgravity, albeit in different ways: during hypergravity, the distance to the skin decreased for the upper ( p = 0.016) and the lower sensor ( p = 0.036). During microgravity, the upper sensor showed a significant increase ( p = 0.016), and the lower showed a decrease ( p = 0.005) in distance. This study emphasizes the role of spinal motor control adaptations in changing gravity conditions. Both hypergravity and microgravity lead to changes in spinal motor control. The decrease in spinal stiffness during hypergravity is interpreted as a shift of the axial load from the spine to the pelvis and thoracic cage. In microgravity, activity of the multifidi and of the psoas muscles seems to ensure the integrity of the spine. Swiss (BASEC-NR: 2018-00051)/French “EST-III” (Nr-ID-RCB: 2018-A011294-51/Nr-CPP: 18.06.09).

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“…These changes affect astronaut health during space flight and also have long-term health consequences upon their return to Earth (20,22). Returning astronauts experience decreased muscle endurance and strength (12), leading to muscle fatigue and low back pain (1,23). This makes it difficult to resume normal activities and may raise susceptibility to fractures and osteoporosis (4).…”

Section: Introductionmentioning

confidence: 99%

A novel partial gravity ground-based analog for rats via quadrupedal unloading

Mortreux

Nagy

et al. 2018

Journal of Applied Physiology

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Musculoskeletal deconditioning is a well-known consequence of microgravity. However, the effects of partial gravity, such as that experienced on the moon (0.16 g) or Mars (0.38 g), on musculoskeletal health remain relatively unexplored. Because Mars is being increasingly viewed as the likely next extraterrestrial site for human exploration, there is an increasing need for Earth-based models that can replicate the long-term physiological effects of microgravity. These models would also offer the opportunity to explore the potential impact of partial artificial gravity (as would be achieved by centrifugation). In this study, we describe a novel partial gravity model that can be employed in rats over extended periods of time. We demonstrate that 2 wk of partial weight bearing at 20, 40, or 70% of normal loading affects the musculoskeletal health of the animals, as evidenced by decreased trabecular bone density (ranging from -7.5 ± 2.7% at 70% of normal loading to -27.9 ± 2.9% at 20%), hindlimb muscle mass, and impaired muscle function as characterized by grip force. This new model will facilitate studies of the physiological changes occurring in partial gravity and allow for the design of potential countermeasures to mitigate these changes. NEW & NOTEWORTHY This research article describes the first quadrupedal unloading model in rats that is sustainable for investigating the physiological alterations occurring in partial gravity environments, providing a new and adaptable model for ground-based research for future space exploration.

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From the international space station to the clinic: how prolonged unloading may disrupt lumbar spine stability

Cited by 105 publications

References 57 publications

Effects of Long-Duration Spaceflight on Vertebral Strength and Risk of Spine Fracture

Effects of Long-Duration Spaceflight on Vertebral Strength and Risk of Spine Fracture

Microgravity and Hypergravity Induced by Parabolic Flight Differently Affect Lumbar Spinal Stiffness

A novel partial gravity ground-based analog for rats via quadrupedal unloading

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