Evaluation of Treadmill Exercise in a Lower Body Negative Pressure Chamber as a Countermeasure for Weightlessness-Induced Bone Loss: A Bed Rest Study With Identical Twins

Smith, Scott M.; Davis-Street, Janis; Fesperman, J. Vernell; Calkins, DS; Bawa, Maneesh; Macias, Brandon R.; Meyer, R. Scott; Hargens, Alan R.

doi:10.1359/jbmr.2003.18.12.2223

Cited by 89 publications

(102 citation statements)

References 37 publications

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“…The primary objective of the present study was to determine if the LBNP treadmill exercise protocol would mitigate bone loss in women to a degree similar to that observed in men [36]. A secondary objective was to determine if the effect of dietary acid load on bone metabolism that we found in men [49] was evident in women.…”

Section: Introductionmentioning

confidence: 86%

“…Although in this report we compare the data from female subjects with data from male subjects published earlier [36,49], none of the data from female subjects, nor the heritability data for men or women, have been published previously.…”

Section: Methodsmentioning

confidence: 97%

“…We have previously published reports [9,19,28,36,49] of a study with male subjects in which we used procedures identical to those used for the study reported here. Although in this report we compare the data from female subjects with data from male subjects published earlier [36,49], none of the data from female subjects, nor the heritability data for men or women, have been published previously.…”

Section: Methodsmentioning

confidence: 99%

“…The EX subjects exercised in an LBNP chamber with a sealed flexible waist seal [9,28,36,43]. On 6 d per week, during LBNP, the EX subjects exercised for 40 min (40-80% pre-bed rest peak oxygen consumption) and then rested for 5 min during LBNP.…”

Section: Lbnp Exercise Protocolmentioning

confidence: 99%

“…In a recent study of male identical twins [28], we found that supine treadmill exercise within lower body negative pressure (LBNP) mitigated some of the muscle [9] and bone [36] deconditioning associated with microgravity simulated by head-down-tilt bed rest. Moreover, dietary patterns in these subjects had a noticeable effect on the degree of bone loss during bed rest [49].…”

Section: Introductionmentioning

confidence: 99%

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Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

Zwart

Hargens

Lee

et al. 2007

Bone

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Supine weight-bearing exercise within lower body negative pressure (LBNP) alleviates some of the skeletal deconditioning induced by simulated weightlessness in men. We examined the potential beneficial effect in women. Because dietary acid load affected the degree of bone resorption in men during bed rest, we also investigated this variable in women. Subjects were 7 pairs of female identical twins assigned at random to 2 groups, sedentary bed rest (control) or bed rest with supine treadmill exercise within LBNP. Dietary intake was controlled and monitored. Urinary calcium and markers of bone resorption were measured before bed rest (BR) and on BR days 5/6, 12/13, 19/20, and 26/27. Bone mineral content was assessed by dual-energy X-ray absorptiometry before and after bed rest. Data were analyzed by repeated measures two-way analysis of variance. Pearson correlation coefficients were used to define the relationships between diet and markers of bone metabolism, and to estimate heritability of markers. During bed rest, all markers of bone resorption and urinary calcium and phosphorus increased (P < 0.001); parathyroid hormone (P = 0.06), bone-specific alkaline phosphatase (P = 0.06), and 1,25-dihydroxyvitamin D (P = 0.09) tended to decrease. LBNP exercise tended to mitigate bone density loss. The ratio of dietary animal protein to potassium was positively correlated with urinary calcium excretion for all weeks of bed rest in the control group, but only during weeks 1 and 3 for the exercise group. Pre-bed rest data suggested that many markers of bone metabolism have strong genetic determinants. Treadmill exercise within LBNP had less of a protective effect on bone resorption during bed rest in women than previously-published results had Sources of support: This study was funded by NASA through grant NAG 9-1425 and by NIH through grant GCRC M01-RR00827 to UCSD.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. shown for its effect in men, but the same trends were observed for both sexes. Dietary acid load of these female subjects was significantly correlated with calcium excretion but not with other bone resorption markers. NIH Public Access

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Section: Introductionmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Lbnp Exercise Protocolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

Zwart

Hargens

Lee

et al. 2007

Bone

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Microgravity Stress: Bone and Connective Tissue

Bloomfield

Martinez

Boudreaux

et al. 2016

Comprehensive Physiology

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The major alterations in bone and the dense connective tissues in humans and animals exposed to microgravity illustrate the dependency of these tissues' function on normal gravitational loading. Whether these alterations depend solely on the reduced mechanical loading of zero g or are compounded by fluid shifts, altered tissue blood flow, radiation exposure, and altered nutritional status is not yet well defined. Changes in the dense connective tissues and intervertebral disks are generally smaller in magnitude but occur more rapidly than those in mineralized bone with transitions to 0 g and during recovery once back to the loading provided by 1 g conditions. However, joint injuries are projected to occur much more often than the more catastrophic bone fracture during exploration class missions, so protecting the integrity of both tissues is important. This review focuses on the research performed over the last 20 years in humans and animals exposed to actual spaceflight, as well as on knowledge gained from pertinent ground-based models such as bed rest in humans and hindlimb unloading in rodents. Significant progress has been made in our understanding of the mechanisms for alterations in bone and connective tissues with exposure to microgravity, but intriguing questions remain to be solved, particularly with reference to biomedical risks associated with prolonged exploration missions.

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The current state of bone loss research: Data from spaceflight and microgravity simulators

Nagaraja

Risin

2013

J of Cellular Biochemistry

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Bone loss is a well documented phenomenon occurring in humans both in short- and in long-term spaceflights. This phenomenon can be also reproduced on the ground in human and animals and also modeled in cell-based analogs. Since space flights are infrequent and expensive to study the biomedical effects of microgravity on the human body, much of the known pathology of bone loss comes from experimental studies. The most commonly used in vitro simulators of microgravity are clinostats while in vivo simulators include the bed rest studies in humans and hindlimb unloading experiments in animals. Despite the numerous reports that have documented bone loss in wide ranges in multiple crew members, the pathology remains a key concern and development of effective countermeasures is still a major task. Thus far, the offered modalities have not shown much success in preventing or alleviating bone loss in astronauts and cosmonauts. The objective of this review is to capture the most recent research on bone loss from spaceflights, bed rest and hindlimb unloading, and in vitro studies utilizing cellular models in clinostats. Additionally, this review offers projections on where the research has to focus to ensure the most rapid development of effective countermeasures.

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Evaluation of Treadmill Exercise in a Lower Body Negative Pressure Chamber as a Countermeasure for Weightlessness-Induced Bone Loss: A Bed Rest Study With Identical Twins

Cited by 89 publications

References 37 publications

Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

Microgravity Stress: Bone and Connective Tissue

The current state of bone loss research: Data from spaceflight and microgravity simulators

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