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Background: Changes in blood vessel properties have been identified with confinement, spaceflight, bedrest, and dry immersion. Subsequently, it was suspected that other organs may also be affected in these extreme environments. The purposes of the current study were to determine the effects of head-down bedrest (HDT) on cardiovascular and organ measurements made using ultrasound imaging similar to that currently available on the International Space Station, and to evaluate the efficacy of two different countermeasure protocols in preventing any observed changes in the ultrasound measurements with HDT. Methods: Ultrasound measures were conducted on 24 individuals (3 groups of 8) pre HDT and on day 55 of the HDT. The control group (C°) remained in passive HDT for the 55 days, the C1 group performed aerobic exercise daily (EX), and the C2 group practiced aerobic exercise under artificial gravity conditions (EX-AG). Fifteen parameters were measured on 10 different organs and blood vessels including the right common carotid artery, abdominal aorta, right tibial artery, left ventricle, right jugular vein, portal vein, right kidney, cervical and lumbar vertebra, and the vastus intermedius muscle. Results: HDT resulted in changes for many of the parameters investigated. Observed changes in carotid IMT and distensibility, cardiac ejection fraction, portal vein diameter, and vastus intermedius muscle thickness were attenuated with EX and EX-AG, with EX-AG having a greater effect than exercise alone on measures of carotid distensibility. Conclusion: Results from this study indicate changes in many structures assessed with ultrasound imaging after 55 days of HDT bedrest with some changes being attenuated with the two investigated countermeasure protocols. [ABSTRACT FROM AUTHOR]

Blood flow restriction (BFR) has been identified as a potential countermeasure to mitigate physiological deconditioning during spaceflight. Guidelines recommend that tourniquet pressure be prescribed relative to limb occlusion pressure (LOP); however, it is unclear whether body tilting or reduced gravity analogues influence LOP. We examined LOP at the leg and arm during supine bedrest and bodyweight suspension (BWS) at 6° head‐down tilt (HDT), horizontal (0°), and 9.5° head‐up tilt (HUT) positions. Twenty‐seven adults (age, 26 ± 5 years; height, 1.75 ± 0.08 m; body mass, 73 ± 12 kg) completed all tilts during bedrest. A subgroup (n = 15) additionally completed the tilts during BWS. In each position, LOP was measured twice in the leg and arm using the Delfi Personalized Tourniquet System after 5 min of rest and again after a further 5 min. The LOP at the leg increased significantly from 6° HDT to 9.5° HUT in bedrest and BWS by 9–15 mmHg (Cohen's d = 0.7–1.0). Leg LOP was significantly higher during BWS at horizontal and 9.5° HUT postures relative to the same angles during bedrest by 8 mmHg (Cohen's d = 0.6). Arm LOP remained unchanged between body tilts and analogues. Intraclass correlation coefficients for LOP measurements taken after an initial and subsequent 5 min rest period in all conditions ranged between 0.91–0.95 (leg) and 0.83–0.96 (arm). It is advised that LOP be measured before the application of a vascular occlusion in the same body tilt/setting to which it is applied to minimize discrepancies between the actual and prescribed tourniquet pressure. [ABSTRACT FROM AUTHOR]

Long-duration bedrest impairs upright postural and locomotor control, prompting the need for assessment tools to predict the effects of deconditioning on post-bedrest outcome measures. We developed a tilt board mounted vertically with a horizontal air-bearing sled as a potential supine assessment tool for a future bedrest study. The purpose of this pilot study was to examine the association between supine proprioceptive assessments on the tilt board and upright functional mobility. Seventeen healthy participants completed variations of a supine tilt board task and an upright functional mobility task (FMT), which is an established obstacle avoidance course. During the supine tasks, participants lay on the air-bearing sled with axial loading toward the tilt board. Participants tilted the board to capture virtual targets on an overhead monitor during 30 s trials. The tasks included two dynamic tasks (i.e., double-leg stance matching mediolateral tilt targets over ±3° or ±9° ranges) and two static tasks (i.e., single-leg stance maintaining a central target position). The performances during the dynamic tasks were significantly correlated with the FMT time to completion. The dominant-leg static task performance showed a moderate trend with the FMT time to completion. The results indicate that supine proprioceptive assessments may be associated with upright ambulation performance, and thus, support the proposed application in bedrest studies. [ABSTRACT FROM AUTHOR]

BackgroundChanges in blood vessel properties have been identified with confinement, spaceflight, bedrest, and dry immersion. Subsequently, it was suspected that other organs may also be affected in these extreme environments. The purposes of the current study were to determine the effects of head-down bedrest (HDT) on cardiovascular and organ measurements made using ultrasound imaging similar to that currently available on the International Space Station, and to evaluate the efficacy of two different countermeasure protocols in preventing any observed changes in the ultrasound measurements with HDT.MethodsUltrasound measures were conducted on 24 individuals (3 groups of 8) pre HDT and on day 55 of the HDT. The control group (C°) remained in passive HDT for the 55 days, the C1 group performed aerobic exercise daily (EX), and the C2 group practiced aerobic exercise under artificial gravity conditions (EX-AG). Fifteen parameters were measured on 10 different organs and blood vessels including the right common carotid artery, abdominal aorta, right tibial artery, left ventricle, right jugular vein, portal vein, right kidney, cervical and lumbar vertebra, and the vastus intermedius muscle.ResultsHDT resulted in changes for many of the parameters investigated. Observed changes in carotid IMT and distensibility, cardiac ejection fraction, portal vein diameter, and vastus intermedius muscle thickness were attenuated with EX and EX-AG, with EX-AG having a greater effect than exercise alone on measures of carotid distensibility.ConclusionResults from this study indicate changes in many structures assessed with ultrasound imaging after 55 days of HDT bedrest with some changes being attenuated with the two investigated countermeasure protocols.

Background Orthostatic intolerance occurs following immobilization in patients on Earth and in astronauts after spaceflight. Head‐down tilt bedrest is a terrestrial model for weightlessness and induces orthostatic intolerance. We hypothesized that lower‐body negative pressure (LBNP) or cycling followed by wearing venous constrictive thigh cuffs mitigates orthostatic intolerance after head‐down tilt bedrest. Methods and Results We enrolled 47 healthy individuals (20 women, 35±9 years) to a 30‐day strict head‐down tilt bedrest study. During bedrest, they were assigned to 6 hours of 25 mm Hg LBNP (n=12) per day and 1 hour of supine cycling followed by 6 hours of venous constriction through thigh cuffs 6 days per week (n=12), 6 hours of daily upright sitting (positive control, n=11), or no countermeasure (negative control, n=12). We measured orthostatic tolerance as the time to presyncope during 80° head‐up tilt testing with incremental LBNP before and immediately after bedrest. We determined plasma volume with carbon monoxide rebreathing before and at the end of bedrest. After bedrest, orthostatic tolerance decreased 540±457 seconds in the control group, 539±68 seconds in the cycling group, 217±379 seconds in the LBNP group, and 289±89 seconds in the seated group (P

Abstract Weightlessness during spaceflight can harm various bodily systems, including bone density, muscle mass, strength and cognitive functions. Exercise appears to somewhat counteract these effects. A terrestrial model for this is head‐down bedrest (HDBR), simulating gravity loss. This mirrors challenges faced by older adults in extended bedrest and space environments. The first Canadian study, backed by the Canadian Space Agency, Canadian Institutes of Health Research, and Canadian Frailty Network, aims to explore these issues. The study seeks to: (1) scrutinize the impact of 14‐day HDBR on physiological, psychological and neurocognitive systems, and (2) assess the benefits of exercise during HDBR. Eight teams developed distinct protocols, harmonized in three videoconferences, at the McGill University Health Center. Over 26 days, 23 participants aged 55–65 underwent baseline measurements, 14 days of −6° HDBR, and 7 days of recovery. Half did prescribed exercise thrice daily combining resistance and endurance exercise for a total duration of 1 h. Assessments included demographics, cardiorespiratory fitness, bone health, body composition, quality of life, mental health, cognition, muscle health and biomarkers. This study has yielded some published outcomes, with more forthcoming. Findings will enrich our comprehension of HDBR effects, guiding future strategies for astronaut well‐being and aiding bedrest‐bound older adults. By outlining evidence‐based interventions, this research supports both space travellers and those enduring prolonged bedrest.

Weightlessness during spaceflight can harm various bodily systems, including bone density, muscle mass, strength and cognitive functions. Exercise appears to somewhat counteract these effects. A terrestrial model for this is head‐down bedrest (HDBR), simulating gravity loss. This mirrors challenges faced by older adults in extended bedrest and space environments. The first Canadian study, backed by the Canadian Space Agency, Canadian Institutes of Health Research, and Canadian Frailty Network, aims to explore these issues. The study seeks to: (1) scrutinize the impact of 14‐day HDBR on physiological, psychological and neurocognitive systems, and (2) assess the benefits of exercise during HDBR. Eight teams developed distinct protocols, harmonized in three videoconferences, at the McGill University Health Center. Over 26 days, 23 participants aged 55–65 underwent baseline measurements, 14 days of −6° HDBR, and 7 days of recovery. Half did prescribed exercise thrice daily combining resistance and endurance exercise for a total duration of 1 h. Assessments included demographics, cardiorespiratory fitness, bone health, body composition, quality of life, mental health, cognition, muscle health and biomarkers. This study has yielded some published outcomes, with more forthcoming. Findings will enrich our comprehension of HDBR effects, guiding future strategies for astronaut well‐being and aiding bedrest‐bound older adults. By outlining evidence‐based interventions, this research supports both space travellers and those enduring prolonged bedrest. [ABSTRACT FROM AUTHOR]

Long-duration bedrest impairs upright postural and locomotor control, prompting the need for assessment tools to predict the effects of deconditioning on post-bedrest outcome measures. We developed a tilt board mounted vertically with a horizontal air-bearing sled as a potential supine assessment tool for a future bedrest study. The purpose of this pilot study was to examine the association between supine proprioceptive assessments on the tilt board and upright functional mobility. Seventeen healthy participants completed variations of a supine tilt board task and an upright functional mobility task (FMT), which is an established obstacle avoidance course. During the supine tasks, participants lay on the air-bearing sled with axial loading toward the tilt board. Participants tilted the board to capture virtual targets on an overhead monitor during 30 s trials. The tasks included two dynamic tasks (i.e., double-leg stance matching mediolateral tilt targets over ±3° or ±9° ranges) and two static tasks (i.e., single-leg stance maintaining a central target position). The performances during the dynamic tasks were significantly correlated with the FMT time to completion. The dominant-leg static task performance showed a moderate trend with the FMT time to completion. The results indicate that supine proprioceptive assessments may be associated with upright ambulation performance, and thus, support the proposed application in bedrest studies.

Purpose: Orthostatic intolerance commonly occurs following immobilization or space flight. We hypothesized that daily artificial gravity training through short-arm centrifugation could help to maintain orthostatic tolerance following head-down tilt bedrest, which is an established terrestrial model for weightlessness. Methods: We studied 24 healthy persons (eight women; age 33.3 ± 9.0 years; BMI 24.3 ± 2.1 kg/m2) who participated in the 60-days head-down tilt bedrest (AGBRESA) study. They were assigned to 30 min/day continuous or 6 × 5 min intermittent short-arm centrifugation with 1Gz at the center of mass or a control group. We performed head-up tilt testing with incremental lower-body negative pressure until presyncope before and after bedrest. We recorded an electrocardiogram, beat-to-beat finger blood pressure, and brachial blood pressure and obtained blood samples from an antecubital venous catheter. Orthostatic tolerance was defined as time to presyncope. We related changes in orthostatic tolerance to changes in plasma volume determined by carbon dioxide rebreathing. Results: Compared with baseline measurements, supine and upright heart rate increased in all three groups following head-down tilt bedrest. Compared with baseline measurements, time to presyncope decreased by 323 ± 235 s with continuous centrifugation, by 296 ± 508 s with intermittent centrifugation, and by 801 ± 354 s in the control group (p = 0.0249 between interventions). The change in orthostatic tolerance was not correlated with changes in plasma volume. Conclusions: Daily artificial gravity training on a short-arm centrifuge attenuated the reduction in orthostatic tolerance after 60 days of head-down tilt bedrest. [ABSTRACT FROM AUTHOR]

Physical inactivity increases cardiometabolic risk through a variety of mechanisms, among which alterations of immunological, metabolic, and autonomic control systems may play a pivotal role. Physical inactivity is frequently associated with other factors that may further worsen prognosis. The association between physical inactivity and hypoxia is particularly interesting and characterizes several conditions—whether physiological (e.g., residing or trekking at high altitude and space flights) or pathological (e.g., chronic cardiopulmonary diseases and COVID-19). In this randomized intervention study, we investigated the combined effects of physical inactivity and hypoxia on autonomic control in eleven healthy and physically active male volunteers, both at baseline (ambulatory) conditions and, in a randomized order, hypoxic ambulatory, hypoxic bedrest, and normoxic bedrest (i.e., a simple experimental model of physical inactivity). Autoregressive spectral analysis of cardiovascular variabilities was employed to assess cardiac autonomic control. Notably, we found hypoxia to be associated with an impairment of cardiac autonomic control, especially when combined with bedrest. In particular, we observed an impairment of indices of baroreflex control, a reduction in the marker of prevalent vagal control to the SA node, and an increase in the marker of sympathetic control to vasculature. [ABSTRACT FROM AUTHOR]

The time line in IVF is critical, as the procedures are associated with the time of the ovulation trigger for follicular maturation, followed by sequential procedures in relation to it. Starting from oocyte recovery scheduled 36 hours post-trigger, the laboratory procedures are followed up sequentially. Oocyte cumulus complex (OCC) may be incubated until insemination or ICSI until 40 hours post-trigger. Conventional insemination may be done either short (4-6 hours) or long insemination (overnight). However, short insemination is associated with an increase in the 3-PN rate. OCC for ICSI may be denuded at least after 38 hours post-trigger, and ICSI may be performed within 2 to 4 hours post-denuding. ICSI done within 2 hours post-denuding appears to be yielding better-quality embryos. Time-lapse studies have indicated that it is possible to obtain higher clinical and live birth rates with embryos reaching the blastocyst stage faster than other embryos. Embryo transfers done with Day 3 embryos result in a higher pregnancy rate than Day 2 while blastocyst transfers perform better than day 3 transfers. Mobilization of patients after ET may not affect the outcome. [ABSTRACT FROM AUTHOR]

Although a number of studies have examined cognitive functions in space, the reasons behind the observed changes described by space research and anecdotal reports have not yet been elucidated. A potential source of cognitive changes is the cephalad fluid shift in the body caused by the lack of hydrostatic pressure under microgravity. These alterations can be modeled under terrestrial conditions using ground-based studies, such as head-down tilt bedrest (HDBR). In this review, we compare the results of the space and HDBR cognitive research. Results for baseline and in-flight/in-HDBR comparisons, and for baseline and post-flight/post-HDBR comparisons are detailed regarding sensorimotor skills, time estimation, attention, psychomotor speed, memory, executive functions, reasoning, mathematical processing, and cognitive processing of emotional stimuli. Beyond behavioral performance, results regarding brain electrical activity during simulated and real microgravity environments are also discussed. Finally, we highlight the research gaps and suggest future directions. [ABSTRACT FROM AUTHOR]

Background: While initial studies suggest that same-day discharge or shortened bedrest may be feasible for some patients following atrial fibrillation (AF) ablation, the risks and benefits of this approach remain unclear for patients undergoing hemostasis with figure-of-eight (FO8) suture technique.Methods: We prospectively evaluated access site bleeding, length of hospitalization, urinary catheterization, and other clinical outcomes in patients undergoing AF ablation with 3 hours of bedrest between April and May 2021, and compared them to a control group that had undergone AF ablation with 6 hours of bedrest from April to July 2019. FO8 sutures were used for hemostasis in all patients. Independent risk factors for bleeding and urinary catheterization were determined using multiple logistic regression.Results: Same-day discharge was achieved in 74% of patients in the 3-hour bedrest group compared to 7% of patients in the 6-hour bedrest group (p < 0.001). There were no differences between 3-hour and 6-hour bedrest groups in the rates of serious adverse events (2% vs. 1%, p = 0.45) or rehospitalizations or ED visits (1% vs. 3%, p = 0.45) within 30 days of ablation. The 3-hour bedrest group showed a non-significant trend toward more access site bleeding (15% vs. 8%, p = 0.10), but had a significant reduction in urinary catheterization (27% vs. 64%, p < 0.001) and opioid analgesia use (20% vs. 33%, p = 0.04).Conclusions: Same-day discharge after 3 hours of bedrest is safe and feasible following AF ablation and is not associated with higher rates of complications or rehospitalizations at 30 days. Reduced bedrest resulted in decreased opioid analgesia and urinary catheterization. [ABSTRACT FROM AUTHOR]

We previously observed a range of whole muscle and individual slow and fast myofiber size responses (mean: +4 to -24%) in quadriceps (vastus lateralis) and triceps surae (soleus) muscles of individuals undergoing 70 days of simulated microgravity with or without the NASA SPRINT exercise countermeasures program. The purpose of the current investigation was to further explore, in these same individuals, the content of myonuclei and satellite cells, both of which are key regulators of skeletal muscle mass. Individuals completed 6° head-down-tilt bedrest (BR, n=9), bedrest with resistance and aerobic exercise (BRE, n=9), or bedrest with resistance and aerobic exercise and low-dose testosterone (BRE+T, n=8). The number of myonuclei and satellite cells associated with each slow (myosin heavy chain (MHC) I) and fast (MHC IIa) myofiber in the vastus lateralis was not changed (P>0.05) pre- to post-bedrest within the BR, BRE, or BRE+T groups. Similarly, in the soleus the number of myonuclei associated with each slow and fast myofiber, and the number of satellite cells associated with each slow myofiber were not changed (P>0.05) pre- to post-bedrest within the BR, BRE, or BRE+T groups. It appears that even with relatively large perturbations in muscle mass over a few months of simulated microgravity, or with partially or completely effective exercise countermeasures, human skeletal muscle tightly regulates the abundance of myonuclei and satellite cells. Thus, exercise countermeasures efficacy for skeletal muscle atrophy appears to be independent of myonuclei and satellite cell abundance.

Background: Orthostatic intolerance occurs following immobilization in patients on Earth and in astronauts after spaceflight. Head-down tilt bedrest is a terrestrial model for weightlessness and induces orthostatic intolerance. We hypothesized that lower-body negative pressure (LBNP) or cycling followed by wearing venous constrictive thigh cuffs mitigates orthostatic intolerance after head-down tilt bedrest., Methods and Results: We enrolled 47 healthy individuals (20 women, 35±9 years) to a 30-day strict head-down tilt bedrest study. During bedrest, they were assigned to 6 hours of 25 mm Hg LBNP (n=12) per day and 1 hour of supine cycling followed by 6 hours of venous constriction through thigh cuffs 6 days per week (n=12), 6 hours of daily upright sitting (positive control, n=11), or no countermeasure (negative control, n=12). We measured orthostatic tolerance as the time to presyncope during 80° head-up tilt testing with incremental LBNP before and immediately after bedrest. We determined plasma volume with carbon monoxide rebreathing before and at the end of bedrest. After bedrest, orthostatic tolerance decreased 540±457 seconds in the control group, 539±68 seconds in the cycling group, 217±379 seconds in the LBNP group, and 289±89 seconds in the seated group ( P <0.0001 time point, P =0.009 for group differences). Supine and upright heart rate increased in all groups following bedrest. Plasma volume was only maintained in the cycling group but decreased in all others (interaction countermeasure×time point P <0.0001)., Conclusions: Six hours of moderate LBNP training was as effective as sitting in attenuating orthostatic intolerance after 30 days of head-down tilt bedrest. Daily cycling exercise followed by 6 hours of wearing venous constrictive thigh cuffs, while maintaining plasma volume, did not improve orthostatic tolerance., Registration: URL: https://www.bfarm.de/EN; Identifiers: DRKS00027643 and DRKS00030848.

Background: Activity restriction is a common recommendation given to patients during pregnancy for various indications, despite lack of definitive data showing improvements in pregnancy outcomes., Objective: To determine if activity restriction (AR) in pregnancy is associated with decreased odds of adverse pregnancy outcomes (APOs)., Study Design: Secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b) prospective cohort. Nulliparous singletons were followed at 8 sites from October 2010-September 2013. Demographic and clinical data were collected at 4 timepoints, and participants were surveyed about AR recommendations at 22w0d-29w6d and delivery. We excluded participants missing data on AR and age. Participants were grouped according to history of AR, and APOs included: gestational hypertension (gHTN), preeclampsia/eclampsia, preterm birth (PTB), and small for gestational age (SGA) neonate. Associations between AR and APOs were examined using uni- and multivariable logistic regression models adjusting for a priori identified APO risk factors., Results: Of 10,038 nuMoM2b participants, 9,312 met inclusion criteria and 1,386 (14.9%) were recommended AR; participants identifying as Black (aOR 0.81 [95% CI 0.68-0.98]) or Hispanic (aOR 0.73 [95% CI 0.61-0.87]) were less likely to be placed on AR when compared to those identifying as White. Overall, 3,197 (34.3%) experienced at least one APO (717 [51.7%] of participants with AR compared to 2,480 [31.3%] participants without AR). After adjustment for baseline differences, the AR group had increased odds of gHTN (aOR 1.61 [95% CI 1.35-1.92]), preeclampsia/eclampsia (aOR 2.52 [95% CI 2.06-3.09]) and iatrogenic and spontaneous PTB (aOR 2.98 [95% CI 2.41-3.69]), but not delivery of an SGA neonate., Conclusion: AR in pregnancy was independently associated with increased odds of hypertensive disorders of pregnancy and PTB, but future prospective work is needed to determine potential causality. Further, participants identifying as Black or Hispanic were significantly less likely to be recommended AR compared to those identifying as White. While AR is not an evidence-based practice, these findings suggest bias may impact which patients receive advice to limit activity in pregnancy. El resumen está disponible en Español al final del artículo., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults. [ABSTRACT FROM AUTHOR]

Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults.

Impaired baroreflex control following bedrest and spaceflight severely affects rate of recovery and return to ambulatory tasks. Post-bedrest/spaceflight orthostatic intolerance remains a major concern for bedrest confined older patients and for astronauts on long-duration missions. Here, we investigated how baroreflex changes following cardiovascular unloading were associated with autonomic neural coupling between blood pressure and heart rate in returning astronauts and in healthy participants who had undergone prolonged bedrest. Cardiovascular data collected from 27 shuttle astronauts (8–16 days) were compared with 19 head-down tilt bedrest (HDBR, 60 days) volunteers. In each group, beat-by-beat systolic blood pressure (SBP) and heart period (R-to-R intervals, RR) were collected simultaneously during a supine-to-stand test (5–10 min) conducted around 10 days before launch or HDBR and within 120 min of landing or exiting HDBR. Indices characterizing interaction time (fraction time active), response gain (gain), and control directionality (causality) between SBP and RR (SBP→RR: neural reflex, and RR→SBP: mechanical coupling) during standing were derived from the beat-by-beat data. Following spaceflight, cardiac baroreflex fraction time active was reduced along with neural reflex causality, with much larger reductions seen with HDBR. No change in mechanical causality pre-post flight or HDBR was observed; however, comparison of male and female astronauts indicated that neural and mechanical causality were both lower in females. Altogether, these findings suggest that changes in blood pressure regulation after bedrest and spaceflight are primarily reflex/neurally mediated and provides a target for therapeutic approaches to cardiovascular deconditioning. • Blood pressure regulation is impaired after bedrest/spaceflight. • Such reduced blood pressure control is primarily reflex/neurally mediated. • Females show larger reduction in baroreflex regulation of BP upon return to Earth. [ABSTRACT FROM AUTHOR]

Exposure to actual or simulated microgravity results in alterations of renal function, fluid redistribution, and bone loss, which is coupled to a rise of urinary calcium excretion. We provided evidence that high calcium delivery to the collecting duct reduces local Aquaporin 2 (AQP2)-mediated water reabsorption under vasopressin action, thus limiting the maximal urinary concentration to reduce calcium saturation. To investigate early renal adaptation into simulated microgravity, we investigated the effects of 10 days of strict bedrest in 10 healthy volunteers. We report here that 10 days of inactivity are associated with a transient, significant decrease (day 5) in vasopressin (copeptin) paralleled by a decrease in AQP2 excretion, consistent with an increased central volume to the heart, resulting in reduced water reabsorption. Moreover, bedrest caused a significant increase in calciuria secondary to bone demineralization paralleled by a decrease in PTH. Urinary osteopontin, a glycoprotein exerting a protective effect on stone formation, was significantly reduced during bedrest. Moreover, a significant increase in adrenomedullin (day 5), a peptide with vasodepressor properties, was observed at day 5, which may contribute to the known reduced orthostatic capacity post-bedrest. We conclude that renal function is altered in simulated microgravity and is associated with an early increase in the risk of stone formation and reduced orthostatic capacity post-bedrest within a few days of inactivity. [ABSTRACT FROM AUTHOR]

Exposure to actual or simulated microgravity results in alterations of renal function, fluid redistribution, and bone loss, which is coupled to a rise of urinary calcium excretion. We provided evidence that high calcium delivery to the collecting duct reduces local Aquaporin 2 (AQP2)-mediated water reabsorption under vasopressin action, thus limiting the maximal urinary concentration to reduce calcium saturation. To investigate early renal adaptation into simulated microgravity, we investigated the effects of 10 days of strict bedrest in 10 healthy volunteers. We report here that 10 days of inactivity are associated with a transient, significant decrease (day 5) in vasopressin (copeptin) paralleled by a decrease in AQP2 excretion, consistent with an increased central volume to the heart, resulting in reduced water reabsorption. Moreover, bedrest caused a significant increase in calciuria secondary to bone demineralization paralleled by a decrease in PTH. Urinary osteopontin, a glycoprotein exerting a protective effect on stone formation, was significantly reduced during bedrest. Moreover, a significant increase in adrenomedullin (day 5), a peptide with vasodepressor properties, was observed at day 5, which may contribute to the known reduced orthostatic capacity post-bedrest. We conclude that renal function is altered in simulated microgravity and is associated with an early increase in the risk of stone formation and reduced orthostatic capacity post-bedrest within a few days of inactivity.

Physical inactivity, i.e. not reaching the recommended level of physical activity (PA), and sedentary behaviours (SB), i.e. sitting time, have been associated with increased risk for common metabolic diseases. Recent epidemiological data suggest that high volumes of SB are detrimental to metabolic health, even in the presence of regular exercise, i.e. moderate/vigorous PA. This suggests that the health effects of SB are independent from those of exercise. However, experimentally testing this hypothesis is complicated because of the difficulty in disassociating SB from PA. Bedrest studies, a traditional space science model, can offer new insights. In some bedrest studies, an exercise training protocol has been used to counteract the harmful effects of inactivity. While bedrest induces an inactive and sedentary state, exercise with bedrest represents a unique model of sedentary yet physically active people. Here, we review bedrest studies with and without exercise training. Although exercise training prevents the loss of muscle mass and function, even large volumes of exercise are not sufficient to fully counteract the negative metabolic adaptations triggered by inactivity. This observation supports the existence of independent adverse health effects of SB, but also the potential benefits of non‐exercise activity, i.e. daily living light PA. We gathered available data to examine the complex relationships between exercise, non‐exercise activity, SB and health outcomes. Given the large amount of SB in modern societies, the sole promotion of exercise, i.e. moderate/vigorous PA may be insufficient, and promotion of light PA may be a complimentary approach to improve health. [ABSTRACT FROM AUTHOR]

Background: Immobility in critically ill patients is conditioned by the condition of the disease or by the effect of drugs, but in both cases, it emerges as a problem from the perspective of functional recovery. The decrease in muscle mass and joint amplitude delay or hinder the processes of recovery from spontaneous ventilation and self-care. When bed rest is required, safe rehabilitation nursing care is a resource to mitigate the problems associated with immobility. Objective: Evaluate the results of rehabilitation nursing care after the application of a structured passive joint mobilization care intervention in critically ill patients. Methods: Qualitative study, case study type. The case of an adult person in a critical situation is presented and eight joint mobilization sessions were carried out by a rehabilitation nurse. Joint amplitude was evaluated using goniometry before and after the application of a rehabilitation program. Study approved by the ethics committee. Results: It was found that in 26 days of admission to the intensive care unit, the joint amplitude remained in the different segments and there were gains in the supination movements of the forearm, left hand extension and right knee flexion. Passive joint mobilization exercises did not interfere with the stability of physiological parameters or adaptation to the ventilatory prosthesis. Conclusion: The results reveal that there is no decrease in joint amplitude and are sensitive to rehabilitation nursing care, in a structured and regular mobilization plan. There were gains in health and the minimization of complications associated with immobility. Other studies should be carried out in order to parameterize not only the intervention plan but also the evidence of the results obtained.

Weightlessness can affect the vestibular function, primarily the otolith function, both directly due to the loss of gravitational influence and by eliminating the support and minimizing proprioceptive afferentation, influencing indirectly through the central integrative multisensory structures of the central nervous system (CNS), where the convergence of afferent signals of various sensory modality (primarily visual, vestibular, support and motor) occurs. All this prompted the study of the influence of various afferentations on the otolith-ocular reflex under the conditions of real and simulated weightlessness. Using the video oculography method, 58 Russian cosmonauts, members of long-term missions to the ISS (125–219 days, ~175 days on average), were examined by a static torsional otolith-cervical-ocular reflex (OCOR) with a head tilt to the shoulder at an angle of 30 deg, the otolith-ocular reflex (OOR) when the body is tilted at an angle of 30 deg, and the otolith-ocular reflex when exposed to centrifugal acceleration using a centrifuge (OORCF). Nine out of 58 cosmonauts were examined in microgravity (175 days) as part of the Virtual space experiment (Stage 1). The study of simulation of the spaceflight (SF) factors involved 30 subjects during five- or seven-day horizontal "dry" immersion (DI) and 12 subjects in 60-day head-down tilt (–8 deg) bed rest (BR). The procedure and the corresponding hardware and software used both in studies with the participation of cosmonauts and in model experiments were completely identical. In weightlessness, throughout the whole SF, all the cosmonauts surveyed had a significant OCOR decrease with the presence (from 11 to 55%, depending on the flight day) of the atypical (inversion or absence) otolith-ocular reflex. After SF, on days 1–4 of examination, 80% of the cosmonauts exhibited a significant OCOR/OOR decrease; 34% of the cosmonauts had atypical (inversion or absence of the otolith reflex) vestibular reactions, while no differences were found between OCOR and OOR. Statistically significant differences were found between the values ​of the OCOR/OOR and OORCF reflexes before and on days 4–5, 9–12 after SF. On days 2–3 after SF, no difference between OORCF and OCOR/OOR was observed. The return of the otolith reflex to the baseline took place only on day 9 after SF. The OCOR/OOR study on days 1–3 after DI showed that the otolith-ocular reflex in 47% of those examined was significantly reduced; in 13% of the subjects atypical reactions (absence or inversion of the reflex) were recorded. On days 4–6 after DI, OCOR/OOR returned to the baseline in all subjects. Analysis of OCOR/OOR after the BR experiment showed that only 14% of the surveyed had a significant decrease in OCOR/OOR on day 1 after the experiment. The atypical form of OCOR/OOR (inversion or complete absence of the otolith reflex) after BR was not revealed in contrast to the testers after DI. The results obtained demonstrated the influence of nonvestibular afferentation on the intensity of the otolith-ocular reflex and its dependence on other sensory inputs. [ABSTRACT FROM AUTHOR]

The objective of the present study was to determine the effects of dry immersion, an innovative ground‐based human model of simulated microgravity and extreme physical inactivity, on iron homeostasis and distribution. Twenty young healthy men were recruited and submitted to 5 days of dry immersion (DI). Fasting blood samples and MRI were performed before and after DI exposure to assess iron status, as well as hematological responses. DI increased spleen iron concentrations (SIC), whereas hepatic iron store (HIC) was not affected. Spleen iron sequestration could be due to the concomitant increase in serum hepcidin levels (P <.001). Increased serum unconjugated bilirubin, as well as the rise of serum myoglobin levels support that DI may promote hemolysis and myolysis. These phenomena could contribute to the concomitant increase of serum iron and transferrin saturation levels (P <.001). As HIC remained unchanged, increased serum hepcidin levels could be due both to higher transferrin saturation level, and to low‐grade pro‐inflammatory as suggested by the significant rise of serum ferritin and haptoglobin levels after DI (P =.003 and P =.003, respectively). These observations highlight the need for better assessment of iron metabolism in bedridden patients, and an optimization of the diet currently proposed to astronauts. [ABSTRACT FROM AUTHOR]

This case-study provides a summary of skeletal lesions seen in a case of diagnosed juvenile pulmonary tuberculosis with extensive multifocal bony lesions. Skeleton of a 9-year-old girl who died in the 1940s in Lisbon, Portugal. The remains of this individual are part of the Lisbon skeletal reference collection curated at the National Museum of Natural History and Science. Lesions and paleopathological conditions were identified and documented through macroscopic, radiographic, computed tomographic, and mammographic analysis. The skeleton shows a variety of lytic lesions on the ribs and thoracic vertebrae including complete destruction of the bodies and fusion of the vertebral arches of four vertebrae, kyphosis, and scoliosis. Further pathological conditions were identified, including bone erosion, premature fusion of the left femoral head and greater trochanter, and abnormal size and shape changes to the lower limbs including loss of bone mass and stunting of the long bones. Skeletal lesions are indicative of spondylitis, Pott's disease, and prolonged bedrest. This case is one of the few examples of confirmed juvenile pulmonary tuberculosis with skeletal lesions prior to the antibiotic era. As such, it provides a reference for the skeletal abnormalities which may be observed in archaeological tuberculosis cases. Pulmonary tuberculosis was recorded as cause of death, however there is no documentation to know the length of illness period or the existence of any comorbidities. Consideration of multi-focal lesions is recommended when analyzing individuals with suspected tuberculosis. [ABSTRACT FROM AUTHOR]

Pasien tirah baring jangka lama berisiko mengalami gangguan integritas kulit. Gangguan tersebut dapat diakibatkan oleh tekanan yang lama, iritasi kulit atau imobilisasi (bed rest) yang berakibat timbulnya luka dekubitus. Pasien tirah baring membutuhkan intervensi yang difokuskan pada life support atau organ support yang membutuhkan observasi intensif. Upaya pencegahan luka tekan dilakukan sedini mungkin antara lain dengan pemberian dukungan permukaan (interface pressure). Nilai tekanan interface tinggi berisiko timbulnya ulkus tekanan. Penelitian ini bertujuan mengidentifikasi tekanan interface pada pasien tirah baring. Metode penelitian eksperimental kuasi dengan pre-post test design. Jumlah sampel 48 responden terdiri dari 2 kelompok yaitu kelompok perlakuan diintervensi menggunakan metode hospital corner bed making dan kelompok kontrol diintervensi dengan metode bed making tali sudut. Kedua kelompok dilakukan evaluasi selama 3 hari. Instrumen yang digunakan adalah Portable Interface Pressure sensor: Palm Q. Hasil menunjukkan bahwa perubahan tekanan interface pre dan post pada kelompok kontrol cukup tinggi dan mengalami naik-turun yang bervariatif sehingga lebih berisiko mengalami luka tekan, sedangkan pada kelompok perlakuan cenderung mengalami penurunan dan atau stabil. Disimpulkan bahwa tekanan interface pada metode hospital corner bed making tampak lebih rendah daripada metode bed making tali sudut.

Atrophy, bedrest, calcium, disuse, neuromuscular junction, sarcopenia, skeletal muscle, unloading Keywords: atrophy; bedrest; calcium; disuse; neuromuscular junction; sarcopenia; skeletal muscle; unloading EN atrophy bedrest calcium disuse neuromuscular junction sarcopenia skeletal muscle unloading 4249 4251 3 09/16/21 20210915 NES 210915 Maintaining skeletal muscle mass is essential for normal ambulatory function and metabolism. These data, together with altered expression of genes related to NMJ (e.g. AGRN, CHRNA1 and HOMER2), suggest that just 10 days of bedrest may be sufficient to result in a loss of NMJ stability. [Extracted from the article]

Physical inactivity is common during hospitalisation and poses a threat to functional capacity and independency in the elderly. We aimed to assess the effect of physical activity measurements with visual feedback about time spent in various activities on the average daily time spent out of bed during hospitalisation. We recorded physical activity during hospitalisation by accelerometers and compared the effect of the visual feedback (intervention) with no feedback (control) on time spent out of bed. Patients admitted to the pulmonary ward were invited and assigned to intervention with feedback or control with no feedback in 6 alternating waves of approximately 18 patients each. The order of feedback/no feedback was randomised at the outset of the study. The visual feedback intervention group was provided with visual feedback of the daily time spent in bed, sitting, standing, and walking. The control group did not receive feedback. 93 patients completed the study with a median length of stay of 5 days. Across all patients there were no statistically significant group differences in daily time out of bed; however, patients with independent mobility spent 51 minutes (95% CI 0 to 102; P =.049) more out of bed when provided with visual feedback compared to no feedback. A simple technology assisted physical activity intervention with visual feedback to encourage mobility was not effective at increasing time spent out of bed among hospitalised patients. With feedback, a subgroup of patients with independent walking abilities increased time out of bed and may benefit from this type of intervention. Trial registration: clinicaltrials.gov Identifier: NCT01945749. • Assess effect of a physical activity measuring system with feedback during hospitalisation • Across all patients the visual feedback provided no reduction in time spent out of bed. • Feedback group spent 81 minutes and control spent 64 minutes per day out of bed. • Group difference was 18 minutes per day potentially in favour of the visual feedback. • In a subgroup with independent mobility, feedback resulted in 51 minutes more out of bed. [ABSTRACT FROM AUTHOR]

This paper provides a general overview of key physiological consequences of microgravity experienced during spaceflight and of important parallels and connections to the physiology of aging. Microgravity during spaceflight influences cardiovascular function, cerebral autoregulation, musculoskeletal, and sensorimotor system performance. A great deal of research has been carried out to understand these influences and to provide countermeasures to reduce the observed negative consequences of microgravity on physiological function. Such research can inform and be informed by research related to physiological changes and the deterioration of physiological function due to aging. For example, head-down bedrest is used as a model to study effects of spaceflight deconditioning due to reduced gravity. As hospitalized older persons spend up to 80% of their time in bed, the deconditioning effects of bedrest confinement on physiological functions and parallels with spaceflight deconditioning can be exploited to understand and combat both variations of deconditioning. Deconditioning due to bed confinement in older persons can contribute to a downward spiral of increasing frailty, orthostatic intolerance, falls, and fall-related injury. As astronauts in space spend substantial amounts of time carrying out exercise training to counteract the microgravity-induced deconditioning and to counteract orthostatic intolerance on return to Earth, it is logical to suggest some of these interventions for bed-confined older persons. Synthesizing knowledge regarding deconditioning due to reduced gravitational stress in space and deconditioning during bed confinement allows for a more comprehensive approach that can incorporate aspects such as (mal-) nutrition, muscle strength and function, cardiovascular (de-) conditioning, and cardio-postural interactions. The impact of such integration can provide new insights and lead to methods of value for both space medicine and geriatrics (Geriatrics meets spaceflight!). In particular, such integration can lead to procedures that address the morbidity and the mortality associated with bedrest immobilization and in the rising health care costs associated with an aging population demographic.

Cardiovascular disease continues to be the leading cause of death in the United States. Coronary angiography is one of the most commonly used diagnostic tools in the identification of coronary artery disease, and it remains a prime treatment option for significant coronary artery stenosis. The widely used femoral approach to coronary angiography does not come without significant risk for access site complications, patient complaints of pain, and lengthy bedrest durations. With these concepts in mind came the evolution and implementation of multiple vascular closure devices. The purpose of this study was to compare complication rates after coronary angiography via the femoral approach between mechanical and manual closure techniques, the pain associated with each, and the duration of bedrest employed using a systematic review of the literature. Upon conclusion of the literature review, evidence has shown to provide significant data supporting the use of mechanical closure devices while reducing access site complications, pain, and lengthy bedrest durations when used in appropriate patients.

Study Question: Does 15 min of immobilization after IUI improve pregnancy rates?Summary Answer: Immobilization for 15 min after IUI does not improve pregnancy rates.What Is Known Already: Prior RCTs report a beneficial effect of supine immobilization for 15 min following IUI compared to immediate mobilization, however, these studies can be criticized. Given the importance for the logistics in daily practice and the lack of biological plausibility we planned a replication study prior to potential implementation of this procedure.Study Design, Size, Duration: A single centre RCT, based in an academic setting in the Netherlands, was performed. Participants were randomly assigned for 15 min of supine immobilization following IUI for a maximum of six cycles compared to the standard procedure of immediate mobilization following IUI. Participants and caregivers were not blinded to group assignment. An independent researcher used computer-generated tables to allocate treatments. Stratification occurred to the indication of IUI (unexplained or mild male subfertility). Revelation of allocation took place just before the insemination by the caregiver. The primary outcome was ongoing pregnancy rate per couple.Participants/materials, Setting, Methods: A total of 498 couples diagnosed with unexplained or mild male subfertility and an indication for treatment with IUI were approached and randomized in the study, of which 244 participants were assigned to 15 min of supine immobilization and 254 participants to immediate mobilization.Main Results and the Role Of Chance: Participant characteristics were comparable between the groups, and 236 participants were analysed in the immobilization group, versus 245 in the mobilization group. The ongoing pregnancy rate per couple was not found to be superior in the immobilization group (one-sided P-value = 0.97) with 76/236 ongoing pregnancies (32.2%) being accomplished in the immobilization and 98/245 ongoing pregnancies (40.0%) in the immediate mobilization group (relative risk 0.81; 95% CI [0.63, 1.02], risk difference: -7.8%, 95% CI [-16.4%, 0.8%]). No difference was found in miscarriage rate, multiple gestation rate, live birth rate and time to pregnancy between the groups.Limitations, Reasons For Caution: Owing to discontinuation of the planned treatment not all participants reached six IUI cycles or an ongoing pregnancy. However, this is as expected in IUI treatment and mirrors clinical practice. These participants were equally distributed across the two groups. Women with tubal pathology and endocrine disorders were excluded for this trial, and this might narrow generalizability.Wider Implications Of the Findings: This study shows no positive effect of 15 min of immobilization following IUI on pregnancy rates. Based on available evidence today, including our study, a possible beneficial effect of supine immobilization after IUI is at least doubtful and straightforward implementation does not seem to be justified.Study Funding/competing Interest(s): No funding was received. All authors have nothing to disclose.Trial Registration Number: Dutch Trial Register NTR 2418.Trial Registration Date: 20 July 2010.Date Of First Patient's Enrolment: 11 August 2010. [ABSTRACT FROM AUTHOR]

This paper provides a general overview of key physiological consequences of microgravity experienced during spaceflight and of important parallels and connections to the physiology of aging. Microgravity during spaceflight influences cardiovascular function, cerebral autoregulation, musculoskeletal, and sensorimotor system performance. A great deal of research has been carried out to understand these influences and to provide countermeasures to reduce the observed negative consequences of microgravity on physiological function. Such research can inform and be informed by research related to physiological changes and the deterioration of physiological function due to aging. For example, head-down bedrest is used as a model to study effects of spaceflight deconditioning due to reduced gravity. As hospitalized older persons spend up to 80% of their time in bed, the deconditioning effects of bedrest confinement on physiological functions and parallels with spaceflight deconditioning can be exploited to understand and combat both variations of deconditioning. Deconditioning due to bed confinement in older persons can contribute to a downward spiral of increasing frailty, orthostatic intolerance, falls, and fall-related injury. As astronauts in space spend substantial amounts of time carrying out exercise training to counteract the microgravity-induced deconditioning and to counteract orthostatic intolerance on return to Earth, it is logical to suggest some of these interventions for bed-confined older persons. Synthesizing knowledge regarding deconditioning due to reduced gravitational stress in space and deconditioning during bed confinement allows for a more comprehensive approach that can incorporate aspects such as (mal-) nutrition, muscle strength and function, cardiovascular (de-) conditioning, and cardio-postural interactions. The impact of such integration can provide new insights and lead to methods of value for both space medicine and geriatrics (Geriatrics meets spaceflight!). In particular, such integration can lead to procedures that address the morbidity and the mortality associated with bedrest immobilization and in the rising health care costs associated with an aging population demographic. [ABSTRACT FROM AUTHOR]

Key Points Astronauts have recently been discovered to have impaired vision, with a presentation that resembles syndromes of elevated intracranial pressure on Earth., Gravity has a profound effect on fluid distribution and pressure within the human circulation. In contrast to prevailing theory, we observed that microgravity reduces central venous and intracranial pressure., This being said, intracranial pressure is not reduced to the levels observed in the 90 deg seated upright posture on Earth. Thus, over 24 h in zero gravity, pressure in the brain is slightly above that observed on Earth, which may explain remodelling of the eye in astronauts., Abstract Astronauts have recently been discovered to have impaired vision, with a presentation that resembles syndromes of elevated intracranial pressure (ICP). This syndrome is considered the most mission-critical medical problem identified in the past decade of manned spaceflight. We recruited five men and three women who had an Ommaya reservoir inserted for the delivery of prophylactic CNS chemotherapy, but were free of their malignant disease for at least 1 year. ICP was assessed by placing a fluid-filled 25 gauge butterfly needle into the Ommaya reservoir. Subjects were studied in the upright and supine position, during acute zero gravity (parabolic flight) and prolonged simulated microgravity (6 deg head-down tilt bedrest). ICP was lower when seated in the 90 deg upright posture compared to lying supine (seated, 4 ± 1 vs. supine, 15 ± 2 mmHg). Whilst lying in the supine posture, central venous pressure (supine, 7 ± 3 vs. microgravity, 4 ± 2 mmHg) and ICP (supine, 17 ± 2 vs. microgravity, 13 ± 2 mmHg) were reduced in acute zero gravity, although not to the levels observed in the 90 deg seated upright posture on Earth. Prolonged periods of simulated microgravity did not cause progressive elevations in ICP (supine, 15 ± 2 vs. 24 h head-down tilt, 15 ± 4 mmHg). Complete removal of gravity does not pathologically elevate ICP but does prevent the normal lowering of ICP when upright. These findings suggest the human brain is protected by the daily circadian cycles in regional ICPs, without which pathology may occur. [ABSTRACT FROM AUTHOR]

The purpose of this study was to review the study design, participants, intervention and its outcomes of studies for post-dura puncture headache using systematic review. Total 4234 studies were searched from 1980 to 2016 years,15 studies were included in final. Total 5239 patients were participated in studies, and 10 RCTs studies and 5 observational studies were included. The findings showed that experimental studies used the 24hr bedrest intervention as a control group for comparing the prevalence of headache with the early ambulation intervention group. The prevalence of headache in ambulation group was lower than 24hr bedrest group (except 2 studies). The high risk methodological bias should be considered when understandings the research findings. Based on this study, meta-analysis study for investigating the proper period of time for bedrest should be performed in further study. [ABSTRACT FROM AUTHOR]

While the benefits of physical exercise for a healthy aging are well-recognized, a growing body of evidence shows that sedentary behavior has deleterious health effects independently, to some extent, of physical activity levels. Yet, the increasing prevalence of sedentariness constitutes a major public health issue that contributes to premature aging but the potential cellular mechanisms through which prolonged immobilization may accelerate biological aging remain unestablished. This narrative review summarizes the impact of sedentary behavior using different models of extreme sedentary behaviors including bedrest, unilateral limb suspension and space travel studies, on the hallmarks of aging such as genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. We further highlight the remaining knowledge gaps that need more research in order to promote healthspan extension and to provide future contributions to the field of geroscience. • Sedentary behavior promotes most of the hallmarks of aging in muscular cells. • Its impact may be modulated by age, muscle fiber typology, and sedentary duration. • More research is needed regarding genetic-related hallmarks and cellular senescence. [ABSTRACT FROM AUTHOR]

Objective: To describe how using a supine arm cycle ergometer can safely reduce deconditioning experienced by patients with spinal cord injury or disorder (SCI/D) during their four to six weeks of complete bed rest after surgery to close a stage 4 pressure injury., Design: This pilot project used a newly designed arm cycle ergometer (known as the M-PACE) that extends over the bed, allowing a patient to lie completely supine while exercising., Setting: The M-PACE was designed and built at the Minneapolis Veterans Affairs Health Care System (MVAHCS) and pilot tested at the MVAHCS SCI/D Center., Participants: Patients with SCI/D, recovering from flap surgery and deemed appropriate to use the arm cycle ergometer were enrolled in the pilot study ( n  = 47)., Outcome Measures: A pre-post six-minute arm test (6MAT), a proxy for conditioning, was conducted on a subset ( n  = 15) of participants before and after the supine cycling exercise training program. Participants' rating of perceived exertion (RPE) scores were collected at cessation of each 6MAT. Participants gave feedback on their perception of using the M-PACE., Results/conclusions: The 6MAT RPE was significantly reduced after training with the M-PACE while on bed rest ( P  = 0.003). Also, significantly more rotations were performed after completing the training program ( P  = 0.02). Further, study participants who accessed the M-PACE found using it helped offset the tedium of laying supine during flap surgery recovery. The differences in the 6MAT pre- to post measures indicate the M-PACE should be further studied for offsetting the normal deconditioning that occurs with extended bedrest.