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1.
Life Sci Space Res (Amst) ; 42: 99-107, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39067998

ABSTRACT

Long-duration spaceflight (LDSF) is associated with unique hazards and linked with numerous human health risks including Spaceflight Associated Neuro-ocular Syndrome (SANS). The proposed mechanisms for SANS include microgravity induced cephalad fluid shift and increased Intracranial Pressure (ICP). SANS is a disorder seen only after LDSF and has no direct terrestrial pathologic counterpart as the zero G environment cannot be completely replicated on Earth. Head-down tilt, bed rest studies however have been used as a terrestrial analog and produce the cephalad fluid shift. Some proposed countermeasures for SANS include vasoconstrictive thigh cuffs and lower body negative pressure. Another potential researched countermeasure is the impedance threshold device (ITD) which can reduce ICP. We review the mechanisms of the ITD and its potential use as a countermeasure for SANS.


Subject(s)
Space Flight , Weightlessness , Humans , Weightlessness/adverse effects , Electric Impedance , Syndrome , Bed Rest/adverse effects , Eye Diseases/physiopathology , Eye Diseases/etiology , Weightlessness Countermeasures , Intracranial Pressure , Head-Down Tilt
2.
Can J Cardiol ; 40(8): 1468-1482, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38759726

ABSTRACT

Bedrest as an experimental paradigm or as an in-patient stay for medical reasons has negative consequences for cardiovascular health. The effects of severe inactivity parallel many of the changes experienced with natural aging but over a much shorter duration. Cardiac function is reduced, arteries stiffen, neural reflex responses are impaired, and metabolic and oxidative stress responses impose burden on the heart and vascular systems. The effect of these changes is revealed in studies of integrative function. Aerobic fitness progressively deteriorates with bedrest and tolerance of upright posture is rapidly impaired. In this review we consider the similarities of aging and bedrest-induced cardiovascular deconditioning. We concur with many recent clinical recommendations that early and regular mobility with upright posture will reduce likelihood of hospital-associated disability related to bedrest.


Subject(s)
Bed Rest , Humans , Bed Rest/adverse effects , Cardiovascular Diseases/physiopathology , Cardiovascular Diseases/etiology , Aging, Premature/physiopathology , Aging, Premature/etiology , Cardiovascular Deconditioning/physiology , Aging/physiology
3.
Hypertens Res ; 47(8): 2211-2216, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38783144

ABSTRACT

Orthostatic hypertension, defined by an increase of systolic blood pressure (SBP) of ≥20 mmHg upon standing, harbors an increased cardiovascular risk. We pooled data from two rigorously conducted head-down tilt bedrest studies to test the hypothesis that cardiopulmonary deconditioning and hypovolemia predispose to orthostatic hypertension. With bedrest, peak VO2 decreased by 6 ± 4 mlO2/min/kg (p < 0.0001) and plasma volume by 367 ± 348 ml (p < 0.0001). Supine SBP increased from 127 ± 9 mmHg before to 133 ± 10 mmHg after bedrest (p < 0.0001). In participants with stable hemodynamics following head-up tilt, the incidence of orthostatic hypertension was 2 out of 67 participants before bedrest and 2 out of 57 after bedrest. We conclude that in most healthy persons, cardiovascular deconditioning and volume loss associated with long-term bedrest are not sufficient to cause orthostatic hypertension.


Subject(s)
Bed Rest , Blood Pressure , Head-Down Tilt , Hypertension , Plasma Volume , Humans , Male , Female , Adult , Bed Rest/adverse effects , Middle Aged , Blood Pressure/physiology , Hypertension/physiopathology , Cardiovascular Deconditioning/physiology , Hypovolemia/physiopathology , Hypovolemia/complications , Hemodynamics/physiology , Oxygen Consumption/physiology
4.
J Physiol ; 602(12): 2985-2998, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38766932

ABSTRACT

Prolonged bed rest impairs standing balance but the underlying mechanisms are uncertain. Previous research suggests strength loss is not the cause, leaving impaired sensorimotor control as an alternative. Here we examine vestibular control of posture in 18 male volunteers before and after 60 days of bed rest. Stochastic vestibular stimulation (SVS) was used to evoke sway responses before, 1 and 6 days after bed rest under different head yaw orientations. The directional accuracy and precision of these responses were calculated from ground reaction force vectors. Bed rest caused up to 63% increases in spontaneous standing sway and 31% reductions in leg strength, changes which were uncorrelated. The increase in sway was exacerbated when the eyes were closed. Mean directions of SVS-evoked sway responses were unaffected, being directed towards the anodal ear and rotating in line with head orientation in the same way before and after bed rest. However, individual trial analysis revealed 25%-30% increases in directional variability, which were significantly correlated with the increase in spontaneous sway (r = 0.48-0.71; P ≤ 0.044) and were still elevated on day 6 post-bed rest. This reveals that individual sway responses may be inappropriately oriented, a finding masked by the averaging process. Our results confirm that impaired balance following prolonged bedrest is not related to loss of strength. Rather, they demonstrate that the sensorimotor transformation process which converts vestibular feedback into appropriately directed balance responses is impaired. KEY POINTS: Prolonged inactivity impairs balance but previous research suggests this is not caused by loss of strength. Here we investigated vestibular control of balance before and after 60 days of bed rest using electrical vestibular stimulation (EVS) to evoke sway responses. Spontaneous sway significantly increased and muscle strength reduced following bed rest, but, in keeping with previous research, these two effects were not correlated. While the overall accuracy of EVS-evoked sway responses was unaffected, their directional variability significantly increased following bed rest, and this was correlated with the increases in spontaneous sway. We have shown that the ability to transform head-centred vestibular feedback into an appropriately directed body sway response is negatively affected by prolonged inactivity; this may contribute to the impaired balance commonly observed following bed rest.


Subject(s)
Bed Rest , Postural Balance , Vestibule, Labyrinth , Humans , Male , Postural Balance/physiology , Adult , Vestibule, Labyrinth/physiology , Young Adult
5.
Ann Ital Chir ; 95(2): 174-180, 2024.
Article in English | MEDLINE | ID: mdl-38684495

ABSTRACT

BACKGROUND: Deep vein thrombosis (DVT), a frequent complication following percutaneous nephrolithotomy (PCNL), may lead to severe conditions like pulmonary embolism. Current knowledge on postoperative DVT risk factors is, however, limited. The aim of our study was to investigate the risk of DVT after PCNL. METHODS: A retrospective study was conducted on patients who underwent PCNL from March 2020 to March 2023 at our institution. Patient demographics and clinical data, including, DVT-specific information, preoperative labs, and surgical details, was evaluated. RESULTS: One hundred patients were included. Thirty-two (20 males, 12 females, mean age 52.5 ± 7.4 years) developed lower limb DVT post-surgery, while the remaining 68 (48 males, 20 females, mean age 51.1 ± 5.5 years) had no DVT symptoms. Analysis revealed significant correlations between hyperlipidemia, operating time, postoperative bed rest duration, D-dimer level on the first day after surgery, Caprini risk assessment model (RAM) score, and DVT risk. D-dimer on the first day after percutaneous nephrolithotomy, postoperative bed rest time and Caprini RAM scores were independent risk factors for DVT after PCNL. Sex, age, hypertension status, diabetes status and smoking and drinking habits were not significantly associated with DVT risk. CONCLUSIONS: D-dimer on the first day after PCNL, postoperative bed rest time and Caprini RAM scores were independent risk factors for DVT after PCNL.


Subject(s)
Nephrolithotomy, Percutaneous , Postoperative Complications , Venous Thrombosis , Humans , Female , Male , Middle Aged , Risk Factors , Venous Thrombosis/etiology , Venous Thrombosis/epidemiology , Retrospective Studies , Nephrolithotomy, Percutaneous/adverse effects , Postoperative Complications/etiology , Postoperative Complications/epidemiology , Adult , Fibrin Fibrinogen Degradation Products/analysis , Operative Time , Bed Rest , Risk Assessment
6.
Sci Rep ; 14(1): 9316, 2024 04 23.
Article in English | MEDLINE | ID: mdl-38654027

ABSTRACT

Floatation-REST (Reduced Environmental Stimulation Therapy) minimizes stimulation of the nervous system by immersing subjects in an environment without sound or light while they effortlessly float in thermoneutral water supersaturated with Epsom salt. Here we investigated the relationship between altered states of consciousness (ASC) and its association with the affective changes induced by Floatation-REST. Using a within-subject crossover design, 50 healthy subjects were randomized to 60 min of Floatation-REST or 60 min of Bed-REST (an active control condition that entailed lying supine on a warm waterbed in a dark and quiet room). Following Floatation-REST, subjects felt significantly more relaxed, less anxious, and less tired than after Bed-REST. Floatation-REST also induced significantly more pronounced ASC characterized by the dissolution of body boundaries and the distortion of subjective time. The loss of body boundaries mediated the loss of anxiety, revealing a novel mechanism by which Floatation-REST exerts its anxiolytic effect.


Subject(s)
Consciousness , Humans , Male , Female , Adult , Consciousness/physiology , Anxiety , Young Adult , Cross-Over Studies , Bed Rest , Rest/physiology
8.
Exp Physiol ; 109(6): 873-888, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38424716

ABSTRACT

Bed rest and limb immobilization are models of muscle disuse associated with skeletal muscle atrophy and reduced strength. The purpose of this systematic review was to examine the impact of protein or amino acid provision before and/or during a period of muscle disuse on muscle atrophy (primary outcome), strength and muscle protein synthesis (secondary outcomes) following a disuse period. We performed a systematic review of Embase, MEDLINE, Web of Science, PubMed and Clinical Trials in December 2022. Eligible studies were randomized controlled trials that combined a dietary protein or amino acid intervention versus control during an experimental model of disuse (bed rest or unilateral limb immobilization) in healthy individuals aged ≥18 years. Nine articles from eight independent trials were identified and rated for risk of bias by two authors. A meta-analysis of muscle mass data revealed no effect (standardized mean difference: 0.2; 95% confidence interval: -0.18 to 0.57, P = 0.31) of protein/amino acid intervention in preventing disuse-induced muscle atrophy. Although the meta-analysis was not conducted on strength or muscle protein synthesis data, there was insufficient evidence in the reviewed articles to support the use of protein/amino acid provision in mitigating the disuse-induced decline in either outcome measurement. Additional high-quality studies, including the reporting of randomization procedures and blinding procedures and the provision of statistical analysis plans, might be required to determine whether protein or amino acid provision serves as an effective strategy to attenuate muscle atrophy during periods of disuse.


Subject(s)
Amino Acids , Dietary Proteins , Immobilization , Muscle, Skeletal , Muscular Atrophy , Adult , Humans , Amino Acids/metabolism , Bed Rest/adverse effects , Dietary Proteins/administration & dosage , Immobilization/adverse effects , Muscle Proteins/metabolism , Muscle Proteins/biosynthesis , Muscle Strength/physiology , Muscle, Skeletal/metabolism , Muscle, Skeletal/physiopathology , Muscular Atrophy/metabolism
10.
J Appl Physiol (1985) ; 136(4): 753-763, 2024 Apr 01.
Article in English | MEDLINE | ID: mdl-38357726

ABSTRACT

Sleep and circadian temperature disturbances occur with spaceflight and may, in part, result from the chronically elevated carbon dioxide (CO2) levels on the international space station. Impaired sleep may contribute to decreased glymphatic clearance and, when combined with the chronic headward fluid shift during actual spaceflight or the spaceflight analog head-down tilt bed rest (HDTBR), may contribute to the development of optic disc edema. We determined if strict HDTBR combined with mildly elevated CO2 levels influenced sleep and core temperature and was associated with the development of optic disc edema. Healthy participants (5 females) aged 25-50 yr, underwent 30 days of strict 6° HDTBR with ambient Pco2 = 4 mmHg. Measures of sleep, 24-h core temperature, overnight transcutaneous CO2, and Frisén grade edema were made pre-HDTBR, on HDTBR days 4, 17, 28, and post-HDTBR days 4 and 10. During all HDTBR time points, sleep, core temperature, and overnight transcutaneous CO2 were not different than the pre-HDTBR measurements. However, independent of the HDTBR intervention, the odds ratios {mean [95% confidence interval (CI)]} for developing Frisén grade optic disc edema were statistically significant for each hour below the mean total sleep time (2.2 [1.1-4.4]) and stage 2 nonrapid eye movement (NREM) sleep (4.8 [1.3-18.6]), and above the mean for wake after sleep onset (3.6 [1.2-10.6]) and for each 0.1°C decrease in core temperature amplitude below the mean (4.0 [1.4-11.7]). These data suggest that optic disc edema occurring during HDTBR was more likely to occur in those with short sleep duration and/or blunted temperature amplitude.NEW & NOTEWORTHY We determined that sleep and 24-h core body temperature were unaltered by 30 days exposure to the spaceflight analog strict 6° head-down tilt bed rest (HDTBR) in a 0.5% CO2 environment. However, shorter sleep duration, greater wake after sleep onset, and lower core temperature amplitude present throughout the study were associated with the development of optic disc edema, a key finding of spaceflight-associated neuro-ocular syndrome.


Subject(s)
Papilledema , Space Flight , Female , Humans , Bed Rest , Sleep Duration , Carbon Dioxide , Head-Down Tilt , Temperature , Hypercapnia , Sleep
11.
Exp Physiol ; 109(5): 812-827, 2024 May.
Article in English | MEDLINE | ID: mdl-38372420

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.


Subject(s)
Astronauts , Bed Rest , Humans , Middle Aged , Aged , Canada , Male , Female , Exercise/physiology , Space Flight , Head-Down Tilt/physiology , Cognition/physiology , Quality of Life , Body Composition/physiology , Mental Health , Bone Density/physiology , Cardiorespiratory Fitness/physiology , Weightlessness/adverse effects
12.
J Appl Physiol (1985) ; 136(5): 1015-1039, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38328821

ABSTRACT

The efficacy of the NASA SPRINT exercise countermeasures program for quadriceps (vastus lateralis) and triceps surae (soleus) skeletal muscle health was investigated during 70 days of simulated microgravity. 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). All groups were periodically tested for muscle (n = 9 times) and aerobic (n = 4 times) power during bedrest. In BR, surprisingly, the typical bedrest-induced decrements in vastus lateralis myofiber size and power were either blunted (myosin heavy chain, MHC I) or eliminated (MHC IIa), along with no change (P > 0.05) in %MHC distribution and blunted quadriceps atrophy. In BRE, MHC I (vastus lateralis and soleus) and IIa (vastus lateralis) contractile performance was maintained (P > 0.05) or increased (P < 0.05). Vastus lateralis hybrid fiber percentage was reduced (P < 0.05) and energy metabolism enzymes and capillarization were generally maintained (P > 0.05), while not all of these positive responses were observed in the soleus. Exercise offsets 100% of quadriceps and approximately two-thirds of soleus whole muscle mass loss. Testosterone (BRE + T) did not provide any benefit over exercise alone for either muscle and for some myocellular parameters appeared detrimental. In summary, the periodic testing likely provided a partial exercise countermeasure for the quadriceps in the bedrest group, which is a novel finding given the extremely low exercise dose. The SPRINT exercise program appears to be viable for the quadriceps; however, refinement is needed to completely protect triceps surae myocellular and whole muscle health for astronauts on long-duration spaceflights.NEW & NOTEWORTHY This study provides unique exercise countermeasures development information for astronauts on long-duration spaceflights. The NASA SPRINT program was protective for quadriceps myocellular and whole muscle health, whereas the triceps surae (soleus) was only partially protected as has been shown with other programs. The bedrest control group data may provide beneficial information for overall exercise dose and targeting fast-twitch muscle fibers. Other unique approaches for the triceps surae are needed to supplement existing exercise programs.


Subject(s)
Exercise , Muscle, Skeletal , Myosin Heavy Chains , Quadriceps Muscle , Weightlessness Simulation , Humans , Male , Quadriceps Muscle/physiology , Quadriceps Muscle/metabolism , Weightlessness Simulation/methods , Adult , Exercise/physiology , Myosin Heavy Chains/metabolism , Muscle, Skeletal/physiology , Muscle, Skeletal/metabolism , United States National Aeronautics and Space Administration , United States , Bed Rest/adverse effects , Testosterone/metabolism , Testosterone/blood , Space Flight/methods , Muscular Atrophy/prevention & control , Muscular Atrophy/physiopathology , Resistance Training/methods , Weightlessness/adverse effects , Muscle Strength/physiology
13.
Acta Physiol (Oxf) ; 240(3): e14102, 2024 03.
Article in English | MEDLINE | ID: mdl-38294173

ABSTRACT

AIM: Altered mitochondrial function across various tissues is a key determinant of spaceflight-induced physical deconditioning. In comparison to tissue biopsies, blood cell bioenergetics holds promise as a systemic and more readily accessible biomarker, which was evaluated during head-down tilt bed rest (HDTBR), an established ground-based analog for spaceflight-induced physiological changes in humans. More specifically, this study explored the effects of HDTBR and an exercise countermeasure on mitochondrial respiration in peripheral blood mononuclear cells (PBMCs). METHODS: We subjected 24 healthy participants to a strict 30-day HDTBR protocol. The control group (n = 12) underwent HDTBR only, while the countermeasure group (n = 12) engaged in regular supine cycling exercise followed by veno-occlusive thigh cuffs post-exercise for 6 h. We assessed routine blood parameters 14 days before bed rest, the respiratory capacity of PBMCs via high-resolution respirometry, and citrate synthase activity 2 days before and at day 30 of bed rest. We confirmed PBMC composition by flow cytometry. RESULTS: The change of the PBMC maximal oxidative phosphorylation capacity (OXPHOS) amounted to an 11% increase in the countermeasure group, while it decreased by 10% in the control group (p = 0.04). The limitation of OXPHOS increased in control only while other respiratory states were not affected by either intervention. Correlation analysis revealed positive associations between white blood cells, lymphocytes, and basophils with PBMC bioenergetics in both groups. CONCLUSION: This study reveals that a regular exercise countermeasure has a positive impact on PBMC mitochondrial function, confirming the potential application of blood cell bioenergetics for human spaceflight.


Subject(s)
Bed Rest , Space Flight , Humans , Leukocytes, Mononuclear , Exercise/physiology , Energy Metabolism
14.
Life Sci Space Res (Amst) ; 40: 19-20, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38245344

ABSTRACT

Rapid deconditioning and comprehensive deleterious physiological changes that result in bedrest affect every system, function and cell of the body. It was assumed that the inherent inactivity was the cause of the problem, and that exercise would restore good health (Vernikos, 2018). However, numerous studies exploring different types and bouts of exercise once a day during bedrest produced only partial benefits. The usual frequent signal to the vestibular system of the inner ear and the brain, of changing posture, such as standing up regularly during a normal day's activities, goes silent in the microgravity of space, in bedrest or when sitting continuously. Making frequent use of gravity stimulation by standing up often throughout the day accelerates rehabilitation. Though centrifugation has been used in the aerospace field, this is a new approach in clinical practice. Postural change apart, another type of Gravity Therapy is the passive riding of a human centrifuge with or without activity. Accelerated rehabilitation through Gravity Therapy can get patients up and about, back to health sooner, in addition to cutting practical and emotional costs of rehabilitation dramatically. KEY POINT: Other than getting a good night's sleep, spending too much time in bed is bad for your health.


Subject(s)
Weightlessness , Humans , Centrifugation , Posture , Bed Rest , Exercise/physiology
15.
Cell Rep Med ; 5(1): 101372, 2024 01 16.
Article in English | MEDLINE | ID: mdl-38232697

ABSTRACT

Insulin sensitivity and metabolic flexibility decrease in response to bed rest, but the temporal and causal adaptations in human skeletal muscle metabolism are not fully defined. Here, we use an integrative approach to assess human skeletal muscle metabolism during bed rest and provide a multi-system analysis of how skeletal muscle and the circulatory system adapt to short- and long-term bed rest (German Clinical Trials: DRKS00015677). We uncover that intracellular glycogen accumulation after short-term bed rest accompanies a rapid reduction in systemic insulin sensitivity and less GLUT4 localization at the muscle cell membrane, preventing further intracellular glycogen deposition after long-term bed rest. We provide evidence of a temporal link between the accumulation of intracellular triglycerides, lipotoxic ceramides, and sphingomyelins and an altered skeletal muscle mitochondrial structure and function after long-term bed rest. An intracellular nutrient overload therefore represents a crucial determinant for rapid skeletal muscle insulin insensitivity and mitochondrial alterations after prolonged bed rest.


Subject(s)
Insulin Resistance , Humans , Insulin Resistance/physiology , Bed Rest/adverse effects , Muscle, Skeletal/metabolism , Energy Metabolism/physiology , Glycogen/metabolism
17.
Osteoarthritis Cartilage ; 32(2): 177-186, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37989468

ABSTRACT

OBJECTIVE: To investigate the effects of 21 days of bed rest immobilization (with and without exercise and nutrition interventions) on type II collagen biomarker concentrations in healthy individuals. DESIGN: Twelve healthy male participants (age 34.2 ± 8.3 years; body mass index 22.4 ± 1.7 kg/m²) were exposed to 6 days ambulatory baseline data collection (BDC), 21 days head-down-tilt bed rest (HDT, CON) + interventions (HDT + resistive vibration exercise (2 times/week, 25 minutes): RVE; HDT + RVE + whey protein (0.6 g/kg body weight/day) and bicarbonate supplementation (90 mmol KHCO3/day: NeX), and 6 days of re-ambulation (R) in a cross-over designed study. The starting HDT condition was randomized (CON-RVE-NEX, RVE-NEX-CON, NEX-CON-RVE). Blood and urine samples were collected before, during, and after HDT. Serum concentrations (s) of CPII, C2C, C1,2C, and urinary concentrations (u) of CTX-II and Coll2-1NO2 were measured. RESULTS: Twenty-one days of HDT resulted in increased sCPII (p < 0.001), sC2C (p < 0.001), and sC1,2C (p = 0.001) (highest increases: sCPII (+24.2% - HDT5), sC2C (+24.4% - HDT7), sC1,2C (+13.5% - HDT2). sC2C remained elevated at R+1 (p = 0.002) and R+6 (p < 0.001) compared to baseline. NeX led to lower sCPII (p < 0.001) and sC1,2C (p = 0.003) compared to CON. uCTX-II (second void and 24-hour urine) increased during HDT (p < 0.001, highest increase on HDT21: second void +82.8% (p < 0.001); 24-hour urine + 77.8% (p < 0.001). NeX resulted in lower uCTX-II concentrations in 24-hour urine (p = 0.012) compared to CON. CONCLUSIONS: Twenty-one days of bed rest immobilization results in type II collagen degradation that does not recover within 6 days of resuming ambulation. The combination of resistive vibration exercise and protein/bicarbonate supplementation minimally counteracted this effect.


Subject(s)
Bed Rest , Bicarbonates , Humans , Male , Adult , Collagen Type II , Bed Rest/methods , Exercise Therapy/methods , Head-Down Tilt
18.
Sci Rep ; 13(1): 19258, 2023 11 07.
Article in English | MEDLINE | ID: mdl-37935771

ABSTRACT

Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spaceflight. This study investigates changes in retinal microcirculation during a ten-day bed rest protocol. Ten healthy young males (22.9 ± 4.7 years; body mass index: 23.6 ± 2.5 kg·m-2) participated in a strictly controlled repeated-measures bed rest study lasting ten days. High-resolution images were obtained using a hand-held fundus camera at baseline, daily during the 10 days of bed rest, and 1 day after re-ambulation. Retinal vessel analysis was performed using a semi-automated software system to obtain metrics for retinal arteriolar and venular diameters, central retinal artery equivalent and central retinal vein equivalent, respectively. Data analysis employed a mixed linear model. At the end of the bed rest period, a significant decrease in retinal venular diameter was observed, indicated by a significantly lower central retinal vein equivalent (from 226.1 µm, CI 8.90, to 211.4 µm, CI 8.28, p = .026), while no significant changes in central retinal artery equivalent were noted. Prolonged bed rest confinement resulted in a significant (up to 6.5%) reduction in retinal venular diameter. These findings suggest that the changes in retinal venular diameter during bedrest may be attributed to plasma volume losses and reflect overall (cardio)-vascular deconditioning.


Subject(s)
Retinal Artery , Retinal Vein , Male , Humans , Bed Rest/adverse effects , Retinal Vessels/diagnostic imaging , Retinal Artery/diagnostic imaging , Retinal Vein/diagnostic imaging , Fluorescein Angiography
19.
J Cachexia Sarcopenia Muscle ; 14(6): 2959-2968, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37989600

ABSTRACT

BACKGROUND: Bed rest during hospitalization can negatively impact functional independence and clinical status of older individuals. Strategies focused on maintaining and improving muscle function may help reverse these losses. This study investigated the effects of a short-term multicomponent exercise intervention on maximal strength and muscle power in hospitalized older patients. METHODS: This secondary analysis of a randomized clinical trial was conducted in an acute care unit in a tertiary public hospital. Ninety (39 women) older patients (mean age 87.7 ± 4.8 years) undergoing acute-care hospitalization [median (IQR) duration 8 (1.75) and 8 (3) days for intervention and control groups, respectively]) were randomly assigned to an exercise intervention group (n = 44) or a control group (n = 46). The control group received standard care hospital including physical rehabilitation as needed. The multicomponent exercise intervention was performed for 3 consecutive days during the hospitalization, consisting of individualized power training, balance, and walking exercises. Outcomes assessed at baseline and discharge were maximal strength through 1 repetition maximum test (1RM) in the leg press and bench press exercises, and muscle power output at different loads (≤30% of 1RM and between 45% and 55% of 1RM) in the leg press exercise. Mean peak power during 10 repetitions was assessed at loads between 45% and 55% of 1RM. RESULTS: At discharge, intervention group increased 19.2 kg (Mean Δ% = 40.4%) in leg press 1RM [95% confidence interval (CI): 12.1, 26.2 kg; P < 0.001] and 2.9 kg (Mean Δ% = 19.7%) in bench press 1RM (95% CI: 0.6, 5.2 kg; P < 0.001). The intervention group also increased peak power by 18.8 W (Mean Δ% = 69.2%) (95% CI: 8.4, 29.1 W; P < 0.001) and mean propulsive power by 9.3 (Mean Δ% = 26.8%) W (95% CI: 2.5, 16.1 W; P = 0.002) at loads ≤30% of 1RM. The intervention group also increased peak power by 39.1 W (Mean Δ% = 60.0%) (95% CI: 19.2, 59.0 W; P < 0.001) and mean propulsive power by 22.9 W (Mean Δ% = 64.1%) (95% CI: 11.7, 34.1 W; P < 0.001) at loads between 45% and 55% of 1RM. Mean peak power during the 10 repetitions improved by 20.8 W (Mean Δ% = 36.4%) (95% CI: 3.0, 38.6 W; P = 0.011). No significant changes were observed in the control group for any endpoint. CONCLUSIONS: An individualized multicomponent exercise program including progressive power training performed over 3 days markedly improved muscle strength and power in acutely hospitalized older patients.


Subject(s)
Exercise Therapy , Exercise , Humans , Female , Aged, 80 and over , Bed Rest , Hospitalization , Muscles
20.
Neurosurg Rev ; 46(1): 310, 2023 Nov 22.
Article in English | MEDLINE | ID: mdl-37989906

ABSTRACT

Incidental durotomies are frequent complications of spine surgery associated with cerebrospinal fluid (CSF) leak-related symptoms. Management typically involves prolonged bed rest to reduce CSF pressure at the durotomy site. However, early ambulation may be a safer, effective alternative. PubMed, Web of Science, Embase, Cochrane, and Scopus were systematically searched for studies comparing early ambulation (bed rest ≤ 24 h) with prolonged bed rest (> 24 h) for patients with incidental durotomies in spine surgeries. The outcomes of interest were CSF leak, hypotensive headache, additional surgical repair, pseudomeningocele, and pulmonary complications. Systematic reviews and meta-analysis were performed following the Cochrane Handbook for Systematic Reviews of Interventions. We included a total of 704 patients from 6 studies. There was a significant reduction in the incidence of pulmonary complications (RR 0.23; 95% CI 0.08-0.67; p = 0.007) in the early mobilization group. The incidence of CSF leak (RR 1.34; 95% CI 0.83-2.14; p = 0.23), hypotensive headache (RR 0.72; 95% CI 0.27-1.90; p = 0.50), additional repair surgery (RR 1.29; 95% CI 0.76-2.2; p = 0.35), and pseudomeningocele (RR 1.29; 95% CI 0.20-8.48; p = 0.79) did not differ significantly. In patients with incidental durotomy following spinal surgery, early mobilization was associated with a lower incidence of pulmonary complications as compared with prolonged bed rest. There was no significant difference between groups in terms of CSF leak, need for additional repair, pseudomeningocele, and hypotensive headache.


Subject(s)
Bed Rest , Early Ambulation , Humans , Early Ambulation/adverse effects , Bed Rest/adverse effects , Spine/surgery , Neurosurgical Procedures/adverse effects , Headache/surgery , Cerebrospinal Fluid Leak/surgery , Cerebrospinal Fluid Leak/etiology , Dura Mater/surgery , Postoperative Complications/etiology
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