scholarly journals Indices of Increased Decompression Stress Following Long-Term Bed Rest

2018 ◽  
Vol 9 ◽  
Author(s):  
Mikael Gennser ◽  
S. L. Blogg ◽  
Ola Eiken ◽  
Igor B. Mekjavic
Keyword(s):  
Bed Rest ◽  
Decompression Stress

scholarly journals Long-term bedrest study and astronaut training

2016 ◽  
Author(s):  
Edwin Mulder ◽  
Alexandra Noppe ◽  
Ulrich Limper
Keyword(s):  
Bed Rest ◽  
Dual Purpose ◽  
Planetary Environments ◽  
Exercise Regimen ◽  
Long Duration ◽  
Astronaut Training ◽  
Health Support ◽  
Art Research ◽  
Induced Changes

In the context of space physiology, research is being conducted to understand the physiological effects from radiation, hypogravity, spaceflight and planetary environments. The goal is to identify new methods to address the unique challenges in medical treatment, human factors, and behavioral health support on future exploration missions. As crew size is small and time is limited during actual missions, space agencies resort to addressing the effects of space travel in analog environments that have features similar to those of spaceflight. Head-down tilt bed rest (HDBR), for instance, is one of the established terrestrial models used to simulate some of the physiological changes experienced during spaceflight under weightless conditions and is therefore considered a valuable testbed to prepare for future long-duration exploration missions. HDBR studies are performed in extremely-well controlled laboratory settings, offering the possibility to test the effects of – what is in essence - physical inactivity and fluid shift. However, HDBR studies have a dual purpose, as they are also invaluable for the development, testing and validation of countermeasures aimed at mitigating microgravity-induced changes to the human body. With respect to the latter, the consensus is that short-term bed rest studies (< 14 days) serve foremost as a first screening of potential promising countermeasures, particularly for the cardiovascular system. Screening of preventative procedures and protocols for the muscular system requires at least mid-term (14 -28 days), whereas studies aiming to validate countermeasures for bone require long-term HDBR studies, in the order of 60-90 days. Hitherto the preferred countermeasure during spaceflight has been physical exercise. The presentation will therefore provide a short overview of the current onboard exercise regimen and will, in light of this, outline the scientific background and aims of the ongoing 60-day HDBR study at the :envihab (from the words ‘Environment’ and ‘Habitat’), the DLR Institute of Aerospace Medicine’s state-of-the-art research facility.

Changes in leg vein filling and emptying characteristics and leg volumes during long-term head-down bed rest

1997 ◽  
Vol 82 (6) ◽  
pp. 1726-1733 ◽  
Author(s):  
Francis Louisy ◽  
Philippe Schroiff ◽  
Antonio Güell
Keyword(s):  
Bed Rest ◽  
Venous Occlusion ◽  
Arterial Flow ◽  
Flow Index ◽  
Venous Compliance ◽  
Physiological Factors ◽  
Control Value ◽  
Flow Changes ◽  
Mercury Strain Gauge

Louisy, Francis, Philippe Schroiff, and Antonio Güell.Changes in leg vein filling and emptying characteristics and leg volumes during long-term head-down bed rest. J. Appl. Physiol. 82(6): 1726–1733, 1997.—Leg venous hemodynamics [venous distensibility index (VDI), arterial flow index (AFI), half-emptying time (T1/2)], and leg volumes (LV) were assessed by mercury strain-gauge plethysmography with venous occlusion and volometry, respectively, in seven men before, during, and after 42 days of 6° head-down bed rest. Results showed a high increase in VDI up to day 26 of bed rest (+50% vs. control at day 26, P < 0.05), which tended to subside thereafter (+20% increase vs. control value at day 41, P < 0.05). VDI changes were associated with parallel changes in T1/2 (+54% vs. control at day 26 of bed rest, P < 0.05, and +25% vs. control at day 41, P < 0.05) and with a decrease in AFI (−49% at day 41 vs. control, P < 0.05). LV continuously decreased throughout bed rest (−13% vs. control at day 41, P < 0.05) but was correlated with VDI only during the first month of bed rest. These results show that during long-term 6° head-down bed rest alterations of leg venous compliance are associated with impairment of venous emptying capacities and arterial flow. Changes in skeletal muscle mass and fluid shifts may account for venous changes during the first month of bed rest but, subsequently, other physiological factors, to be determined, may also be involved in leg venous hemodynamic alterations.

Skeletal Muscle Mass Regulation in Critical Illness

2014 ◽  
Author(s):  
Zudin Puthucheary ◽  
Hugh Montgomery ◽  
Nicholas Hart ◽  
Stephen Harridge
Keyword(s):  
Skeletal Muscle ◽  
Critical Illness ◽  
Muscle Mass ◽  
Skeletal Muscle Mass ◽  
Bed Rest ◽  
Protein Homeostasis ◽  
Highly Sensitive ◽  
And Function ◽  
Inadequate Nutrition

Muscle is a dynamic, plastic, and malleable tissue that is highly sensitive to mechanical and metabolic signals. Muscle mass is regulated by protein homeostasis, with protein being continually turned over, reflecting a balance between synthesis and breakdown. This chapter discusses the effect of critical illness on skeletal muscle mass, protein homeostasis, and the intracellular signalling driving anabolism and catabolism. The focus will be on the unique challenges to which the skeletal muscle are exposed, such as inflammation, sepsis, sedation, and inadequate nutrition, which, in combination with the disuse signals of immobilization and bed rest, engender dramatic changes in muscle structure and function. The mechanisms regulating muscle loss during critical illness are being unravelled, but many questions remain unanswered. Detailed understanding of these mechanisms will help drive strategies to minimize or prevent intensive care-acquired muscle weakness and the long-term consequences experienced by ICU survivors.

Changes in standing body sway of pregnant women after long-term bed rest

2015 ◽  
Vol 36 (4) ◽  
pp. 479-482
Author(s):  
Y Shibayama ◽  
T. Kuwata ◽  
J. Yamaguchi ◽  
M. Matsumoto ◽  
M. Watanabe ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Bed Rest ◽  
Body Sway

Risk of renal stone formation induced by long-term bed rest could be decreased by premedication with bisphosphonate and increased by resistive exercise

2008 ◽  
Vol 15 (7) ◽  
pp. 630-635 ◽  
Author(s):  
Atsushi Okada ◽  
Hiroshi Ohshima ◽  
Yasunori Itoh ◽  
Takahiro Yasui ◽  
Keiichi Tozawa ◽  
...  
Keyword(s):  
Renal Stone ◽  
Stone Formation ◽  
Bed Rest ◽  
Resistive Exercise

The effects of long-term bed rest on H-reflex and motor evoked potential in the human soleus muscle during standing

1999 ◽  
Vol 266 (2) ◽  
pp. 101-104 ◽  
Author(s):  
Kentaro Yamanaka ◽  
Shin-ichiroh Yamamoto ◽  
Kimitaka Nakazawa ◽  
Hideo Yano ◽  
Yoji Suzuki ◽  
...  
Keyword(s):  
Soleus Muscle ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Bed Rest ◽  
H Reflex

scholarly journals Long-Term Bed Rest Delays the Circadian Phase of Core Body Temperature

2021 ◽  
Vol 12 ◽  
Author(s):  
Stefan Mendt ◽  
Katharina Brauns ◽  
Anika Friedl-Werner ◽  
Daniel L. Belavy ◽  
Mathias Steinach ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Core Body Temperature ◽  
Bed Rest ◽  
Phase Delay ◽  
Activity Levels ◽  
Physical Activity Levels ◽  
Core Body

Spaceflight can be associated with sleep loss and circadian misalignment as a result of non-24 h light-dark cycles, operational shifts in work/rest cycles, high workload under pressure, and psychological factors. Head-down tilt bed rest (HDBR) is an established model to mimic some of the physiological and psychological adaptions observed in spaceflight. Data on the effects of HDBR on circadian rhythms are scarce. To address this gap, we analyzed the change in the circadian rhythm of core body temperature (CBT) in two 60-day HDBR studies sponsored by the European Space Agency [n = 13 men, age: 31.1 ± 8.2 years (M ± SD)]. CBT was recorded for 36 h using a non-invasive and validated dual-sensor heatflux technology during the 3rd and the 8th week of HDBR. Bed rest induced a significant phase delay from the 3rd to the 8th week of HDBR (16.23 vs. 16.68 h, p = 0.005, g = 0.85) irrespective of the study site (p = 0.416, g = −0.46), corresponding to an average phase delay of about 0.9 min per day of HDBR. In conclusion, long-term bed rest weakens the entrainment of the circadian system to the 24-h day. We attribute this effect to the immobilization and reduced physical activity levels associated with HDBR. Given the critical role of diurnal rhythms for various physiological functions and behavior, our findings highlight the importance of monitoring circadian rhythms in circumstances in which gravity or physical activity levels are altered.

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