Changes in musculoskeletal structure and function with prolonged bed rest

Effect of Exercise Rehabilitation in Patients With Acute Heart Failure: A Systematic Review and Meta-analysis

BACKGROUND

Exercise rehabilitation is conducive to increasing functional ability and improving health outcomes, but its effectiveness in patients with acute heart failure (AHF) is still controversial.

PURPOSE

In this study, our aim was to systematically examine the efficacy of exercise rehabilitation in people with AHF.

METHODS

A search was conducted for randomized controlled trial studies on exercise rehabilitation in patients with AHF up to November 2021. Two investigators conducted literature selection, quality assessments, and data extractions independently. The primary outcome was 6-minute walk distance, and the secondary outcomes were left ventricular ejection fraction, quality of life, Short Physical Performance Battery, readmission, and mortality. RevMan (version 5.3) software was used for the meta-analysis.

RESULTS

Twelve studies with 1215 participants were included. Exercise rehabilitation significantly improved the 6-minute walk distance (mean difference [MD], 33.04; 95% confidence interval [CI], 31.37-34.70; P < .001; I2 = 0%), quality of life (MD, -11.57; 95% CI, -19.25 to -3.89; P = .003; I2 = 98%), Short Physical Performance Battery (MD, 1.40; 95% CI, 1.36-1.44; P < .001; I2 = 0%), and rate of readmission for any cause (risk ratio, 0.48; 95% CI, 0.26-0.88; P = .02; I2 = 7%), compared with routine care. However, no statistically significant effects on left ventricular ejection fraction (MD, 0.94; 95% CI, -1.62 to 3.51; P = .47; I2 = 0%) and mortality (risk ratio, 1.07; 95% CI, 0.64-1.80; P = .79; I2 = 0%) were observed.

CONCLUSIONS

Compared with routine care, exercise rehabilitation improved functional ability and quality of life, reducing readmission in patients with AHF.

Exploring the influence of microgravity on chemotherapeutic drug response in cancer: Unveiling new perspectives

Microgravity, an altered gravity condition prevailing in space, has been reported to have a profound impact on human health. Researchers are very keen to comprehensively investigate the impact of microgravity and its intricate involvement in inducing physiological changes. Evidenced transformations were observed in the internal architecture including cytoskeletal organization and cell membrane morphology. These alterations can significantly influence cellular function, signalling pathways and overall cellular behaviour. Further, microgravity has been reported to alter in the expression profile of genes and metabolic pathways related to cellular processes, signalling cascades and structural proteins in cancer cells contributing to the overall changes in the cellular architecture. To investigate the effect of microgravity on cellular and molecular levels numerous ground-based simulation systems employing both in vitro and in vivo models are used. Recently, researchers have explored the possibility of leveraging microgravity to potentially modulate cancer cells against chemotherapy. These findings hold promise for both understanding fundamental processes and could potentially lead to the development of more effective, personalized and innovative approaches in therapeutic advancements against cancer.

Effects of Bed Rest on Physical Performance in Athletes: A Systematic and Narrative Review

BACKGROUND

Athletes can face scenarios in which they are confined to bed rest (e.g., due to injury or illness). Existing research in otherwise healthy individuals indicates that those entering bed rest with the greatest physical performance level might experience the greatest performance decrements, which indirectly suggests that athletes might be more susceptible to the detrimental consequences of bed rest than general populations. Therefore, a comprehensive understanding of the effects of bed rest might help guide the medical care of athletes during and following bed rest.

OBJECTIVE

This systematic and narrative review aimed to (1) establish the evidence for the effects of bed rest on physical performance in athletes; (2) discuss potential countermeasures to offset these negative consequences; and (3) identify the time-course of recovery following bed rest to guide return-to-sport rehabilitation.

METHODS

This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four databases were searched (SPORTDiscus, Web of Science, Scopus, and MEDLINE/PubMed) in October of 2022, and studies were included if they were peer-reviewed investigations, written in English, and investigated the effects of horizontal bed rest on changes in physical capacities and qualities in athletes (defined as Tier 3-5 participants). The reporting quality of the research was assessed using a modified version of the Downs & Black checklist. Furthermore, findings from studies that involved participants in Tiers 1-2 were presented and synthesized using a narrative approach.

RESULTS

Our systematic review of the literature using a rigorous criterion of 'athletes' revealed zero scientific publications. Nevertheless, as a by-product of our search, seven studies were identified that involved apparently healthy individuals who performed specific exercise training prior to bed rest.

CONCLUSIONS

Based on the limited evidence from studies involving non-athletes who were otherwise healthy prior to bed rest, we generally conclude that (1) bed rest rapidly (within 3 days) decreases upright endurance exercise performance, likely due to a rapid loss in plasma volume; whereas strength is reduced within 5 days, likely due to neural factors as well as muscle atrophy; (2) fluid/salt supplementation may be an effective countermeasure to protect against decrements in endurance performance during bed rest; while a broader array of potentially effective countermeasures exists, the efficacy of these countermeasures for previously exercise-trained individuals requires further study; and (3) athletes likely require at least 2-4 weeks of progressive rehabilitation following bed rest of ≤ 28 days, although the timeline of recovery might need to be extended depending on the underlying reason for bed rest (e.g., injury or illness). Despite these general conclusions from studies involving non-athletes, our primary conclusion is that substantial effort and research is still required to quantify the effects of bed rest on physical performance, identify effective countermeasures, and provide return-to-sport timelines in bona fide athletes.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

Registration ID: osf.io/d3aew; Date: October 24, 2022.

Children's growth and motor development following a severe burn: a systematic review

Background

The epidemiological data on post-burn growth, body composition and motor development is ambiguous and scattered. The aim of this systematic review was therefore to summarize the current body of evidence on post-burn growth, body composition and motor development in children.

Methods

A literature search was conducted in PubMed, EMBASE and Web of Science up to March 2021. We considered observational studies that reported (1) metrics on weight, height, body composition, bone mineral content, bone mineral density or motor development, in (2) paediatric burn patients and (3) published in a peer-reviewed journal.

Results

A total of 16 studies were included. Each of the included studies used quantitative methods, but with differing methodology: prospective cohort studies (n = 8), retrospective chart reviews (n = 3), case-control studies (n = 2), cross sectional studies (n = 2) and a retrospective cohort study (n = 1). When combined, the included studies represented 2022 paediatric burn patients, with a mean age of 7.7 (±3.2) years. The average burn size was 52.8% (±12.7) of the total body surface area. Identified outcome measures included weight (n = 12), height (n = 7), muscular strength (n = 4), bone mineral content (n = 5), bone mineral density (n = 5), body mass index (n = 3), fat mass (n = 5), lean body mass (n = 7) and fine and gross motor development (n = 1).

Conclusions

Following an initial decline, patients' growth and motor development started to recover during the first or second year post-burn. Nonetheless, burns may have a profound and prolonged effect on the paediatric burn patients' muscular strength, bone mineral content and lean body mass. It should be noted that the vast majority of studies included only patients with burns covering ≥30% total body surface area. The evidence presented in this review may thus not be representative of the whole paediatric burn population.

Changes in Fat-Free Mass, Protein Intake and Habitual Physical Activity Following Roux-en-Y Gastric Bypass Surgery: A Prospective Study

PURPOSE

Large inter-individual variations in post-bariatric fat-free mass loss (FFML) are observed, which might relate to differences in protein intake and physical activity across patients. We performed repetitive assessments of protein intake and physical activity before and after banded Roux-en-Y gastric bypass surgery, and examined its relations to FFML during 6 months of follow-up.

MATERIALS AND METHODS

FFML (bio-impedance analyses), protein intake (24-h dietary recalls) and moderate-to-vigorous physical activity (MVPA; activPAL) were assessed in 28 patients (4 males, age 42 ± 12 years) before surgery and at 1-, 3- and 6-months post-surgery. Changes in protein intake and MVPA were evaluated with mixed model analysis, whereas associations with FFML were assessed by univariate regression analysis.

RESULTS

Six-month FFML was -7.3 ± 3.6 kg. Protein intake decreased from 80 ± 29 g/day (pre-surgery) to 45 ± 26 g/day (1 month post-surgery (P < 0.001)) and did not improve thereafter (51 ± 21 g/day; P > 0.05). Seven participants (25%) consumed ≥ 60 g protein/day at 6 months post-surgery. Participants performed 7394 ± 2420 steps/day in 54 ± 20 min/day of MVPA, which did not change from pre- to post-surgery (P > 0.05). A higher step count (B = -0.002; 95%CI = [-0.004 - 0.000]; P = 0.048) and higher level of MVPA (B = -0.29; 95%CI = [-0.54 - -0.03]; P = 0.018) were related to a lower FFML.

CONCLUSION

A lower post-surgery FFML was attributable to higher MVPA levels but not protein intake. This may be due to the low total protein intake and the observation that only a minority of patients achieved a protein intake ≥ 60 g/day. Future studies should focus on interventions to increase post-bariatric protein intake and MVPA levels.

Characterising tibialis posterior tendinopathy using the International Classification of Functioning, Disability and Health: a cross sectional study

BACKGROUND

Tibialis posterior tendinopathy (TPT) is characterised by pain around the medial foot/ankle and difficulties weightbearing.

OBJECTIVE

Compare individuals who have TPT with asymptomatic controls across the International Classification of Functioning, Disability and Health (ICF) domains of body structure and function, activity, participation and personal factors.

METHODS

Twenty-two individuals meeting the selection criteria for TPT (86% female, mean ± SD age:43 ± 13 years; body mass index [BMI]:28 ± 7 kg/m²) were compared to 27 controls (93% female, age:44 ± 16 years, BMI:23 ± 5 kg/m²). Standardised differences (and 95% confidence intervals [CIs]) between groups were estimated for outcomes under each ICF domain using Cliff's delta to allow for comparison of the magnitude of deficits across outcomes (>0.47 considered large).

RESULTS

Impairments in body structure and function in individuals with TPT were accompanied by activity limitations including difficulties due to foot problems (-1.0 (-1.0, -1.0)) and with independent living (-0.8 (-1.0, -0.3)) and greater time to complete stair descent/ascent (-0.6 (-0.8, -0.3)). Considering participation, overall foot-related function (-1.0 (-1.0, -1.0)), ability to participate in activities (-0.7 (-0.08, -0.3)), social restrictions (-0.8 (-1.0, -0.4)) and quality of life (-0.7 (-0.9, -0.5)) were poorer in individuals with TPT.

CONCLUSION

Individuals with TPT have large impairments in body structure and function, activity limitations and participation restrictions, particularly relating to independent living, mental health and pain. Personal factors appear to contribute to a lesser extent to the TPT presentation. Treatment plans should consider activity and participation limitations in addition to body structure and function.

Does wing use and disuse cause behavioural and musculoskeletal changes in domestic fowl (Gallus gallus domesticus)?

Domestic chickens may live in environments which restrict wing muscle usage. Notably, reduced wing activity and accompanying muscle weakness are hypothesized risk factors for keel bone fractures and deviations. We used radio-frequency identification (RFID) to measure duration spent at elevated resources (feeders, nest-boxes), ultrasonography to measure muscle thickness (breast and lower leg) changes, radiography and palpation to determine fractures and deviations, respectively, following no, partial (one-sided wing sling) and full (cage) immobilization in white- and brown-feathered birds. We hypothesized partially immobilized hens would reduce elevated resource usage and that both immobilization groups would show decreased pectoralis thickness (disuse) and increased prevalence of fractures and deviations. Elevated nest-box usage was 42% lower following five weeks of partial immobilization for brown-feathered hens but no change in resource usage in white-feathered birds was observed. Fully immobilized, white-feathered hens showed a 17% reduction in pectoralis thickness, while the brown-feathered counterparts showed no change. Lastly, fractures and deviations were not affected in either strain or form of wing immobilization; however, overall low numbers of birds presented with these issues. Altogether, this study shows a profound difference between white- and brown-feathered hens in response to wing immobilization and associated muscle physiology.

Absolute Bed Rest Duration of 3 Days for Osteoporotic Vertebral Fractures: A Retrospective Study

STUDY DESIGN

Retrospective case-control study.

PURPOSE

To reduce unnecessary absolute bed rest (ABR), this study sought to determine the optimal aimed length of ABR in older patients getting conservative treatment for osteoporotic vertebral fractures (OVFs).

OVERVIEW OF LITERATURE

OVFs are quite common in elderly patients. ABR is a vital part of conservative treatment for OVFs, although the length of ABR may increase patient. No recommendations regarding how long ABR should last.

METHODS

This study was conducted in 134 patients with OVFs initially treated conservatively. The patients were split into two groups: 3-day and 7-day ABR. From the time of injury to 1, 4, and 12 weeks after injury, compression rate (CR) and local kyphotic angle (LKA) were assessed and compared between the two groups. Any complications such as pneumonia, deep vein thrombosis, delirium, and urinary tract infection known to be related to ABR were examined based on the electronic medical record.

RESULTS

Forty-four patients underwent ABR for 3 days and 90 underwent ABR for 7 days. There was no significant difference in CR and LKA between the two groups at the time of injury versus 1, 4, and 12 weeks after injury. The patients were divided into two groups: those who received a 3-day ABR and those who received a 7-day ABR. CR and LKA were measured and compared between the two groups from the time of damage to 1, 4, and 12 weeks after injury. The ABR-related complication rate was 43.4% in the 7-day ABR group and 22.7% in 3-day ABR group (p=0.02). The duration of hospital stay was significantly shorter in the 3-day ABR group (12.8 days) than in the 7-day group (16 days) (p=0.01).

CONCLUSIONS

Considering radiological outcomes, prognosis, complications, patient convenience, and economic impact, a 3-day ABR period is appropriate for the conservative treatment of OVFs.

Physical and Quality of Life Changes in Elderly Patients after Laparoscopic Surgery for Colorectal Cancer-A Prospective Cohort Study

Background-The incidence of colorectal cancer is increasing among elderly people, where postoperative complications are frequent. Methods-We evaluated postoperative physical and quality of life changes in elderly patients undergoing laparoscopic surgery for colorectal cancer. A prospective cohort study was performed in 31 colorectal cancer patients ≥60 years who were scheduled for laparoscopic surgery due to colorectal cancer. Outcomes were measured one month preoperative (T1), three days postoperative (T2) and one month postoperative (T3). Results-The largest early postoperative (from T1 to T2) declines were observed for isometric knee extension strength (33.1%), 30 s Chair Stand Test (27.9%) and handgrip strength (16.9%). Significant reductions in quality of life measured with the QLQ-C30 summary score and the EQ 5D index score were found between T1-T3 and T1-T2, respectively. Conclusions-A decline in isometric knee extension strength, 30 s Chair Stand Test, handgrip strength and quality of life is evident in elderly patients in the days following laparoscopic surgery for colorectal cancer. Preoperative values are recovered one month after surgery for all the outcomes, except for isometric knee extension, which should receive especial attention.

The Effects of COVID-19 on Skeletal Muscles, Muscle Fatigue and Rehabilitation Programs Outcomes

Background and Objectives: Consequences due to infection with SARS-CoV-2 virus can have a direct impact on skeletal muscle, due to the fact that both cardiac and skeletal muscle tissue show robust ACE2(angiotensin-converting enzyme 2) expression, suggesting a potential susceptibility to SARS-CoV-2 infection in both types of tissues. From the articles analyzed we concluded that the musculoskeletal damage is firstly produced by the inflammatory effects, cytokine storm and muscle catabolism. However, myopathy, polyneuropathy and therapies such as corticoids were also considered important factors in muscle fatigue and functional incapacity. Pulmonary rehabilitation programs and early mobilization had a highly contribution during the acute phase and post-illness recovery process and helped patients to reduce dyspnea, increase the capacity of physical effort, overcome psychological disorders and improved the quality of their life. Materials and Methods: We have included in this review 33 articles that contain data on muscle damage following SARS-CoV-2 infection. We used the following keywords to search for articles: SARS-CoV-2, COVID-19, muscle weakness, muscle disease, muscle fatigue, neurological disorders. As a search strategy we used PubMed, Cochrane Database of Systematic Reviews; Database of Abstracts of Reviews of Effects and Health Technology Assessment Database to collect the information. We also have chosen the most recent articles published in the last 5 years. Conclusions: Muscular damage, as well as the decrease in the quality of life, are often a consequence of severe SARS-CoV-2 infection through: systemic inflammation, corticotherapy, prolonged bed rest and other unknown factors. Pulmonary rehabilitation programs and early mobilization had a highly contribution during the acute phase and post-illness recovery process and helped patients to reduce dyspnea, increase the capacity of physical effort, overcome psychological disorders and improve the quality of their life.

Skeletal muscle deconditioning during partial weight-bearing in rodents - A systematic review and meta-analysis

Space agencies are planning to send humans back to the Lunar surface, in preparation for crewed exploration of Mars. However, the effect of hypogravity on human skeletal muscle is largely unknown. A recently established rodent partial weight-bearing model has been employed to mimic various levels of hypogravity loading and may provide valuable insights to better understanding how human muscle might respond to this environment. The aim of this study was to perform a systematic review regarding the effects of partial weight-bearing on the morphology and function of rodent skeletal muscle. Five online databases were searched with the following inclusion criteria: population (rodents), intervention (partial weight-bearing for ≥1 week), control (full weight-bearing), outcome(s) (skeletal muscle morphology/function), and study design (animal intervention). Of the 2,993 studies identified, eight were included. Partial weight-bearing at 20%, 40%, and 70% of full loading caused rapid deconditioning of skeletal muscle morphology and function within the first one to two weeks of exposure. Calf circumference, hindlimb wet muscle mass, myofiber cross-sectional area, front/rear paw grip force, and nerve-stimulated plantarflexion force were reduced typically by medium to very large effects. Higher levels of partial weight-bearing often attenuated deconditioning but failed to entirely prevent it. Species and sex mediated the deconditioning response. Risk of bias was low/unclear for most studies. These findings suggest that there is insufficient stimulus to mitigate muscular deconditioning in hypogravity settings highlighting the need to develop countermeasures for maintaining astronaut/cosmonaut muscular health on the Moon and Mars.

Current Perspectives on the Management of Bone Fragments in Open Tibial Fractures: New Developments and Future Directions

Open tibial fractures may be associated with bone loss at the time of the injury or following surgical debridement of the fracture. This article discusses the various treatment options available and the latest developments surrounding the management of free bone fragments in open tibial fractures.

The Impact of COVID-19 and Muscle Fatigue on Cardiorespiratory Fitness and Running Kinetics in Female Recreational Runners

Background: There is evidence that fully recovered COVID-19 patients usually resume physical exercise, but do not perform at the same intensity level performed prior to infection. The aim of this study was to evaluate the impact of COVID-19 infection and recovery as well as muscle fatigue on cardiorespiratory fitness and running biomechanics in female recreational runners.

Methods: Twenty-eight females were divided into a group of hospitalized and recovered COVID-19 patients (COV, n = 14, at least 14 days following recovery) and a group of healthy age-matched controls (CTR, n = 14). Ground reaction forces from stepping on a force plate while barefoot overground running at 3.3 m/s was measured before and after a fatiguing protocol. The fatigue protocol consisted of incrementally increasing running speed until reaching a score of 13 on the 6–20 Borg scale, followed by steady-state running until exhaustion. The effects of group and fatigue were assessed for steady-state running duration, steady-state running speed, ground contact time, vertical instantaneous loading rate and peak propulsion force.

Results: COV runners completed only 56% of the running time achieved by the CTR (p < 0.0001), and at a 26% slower steady-state running speed (p < 0.0001). There were fatigue-related reductions in loading rate (p = 0.004) without group differences. Increased ground contact time (p = 0.002) and reduced peak propulsion force (p = 0.005) were found for COV when compared to CTR.

Conclusion: Our results suggest that female runners who recovered from COVID-19 showed compromised running endurance and altered running kinetics in the form of longer stance periods and weaker propulsion forces. More research is needed in this area using larger sample sizes to confirm our study findings.

Construction and Analysis of Disuse Atrophy Model of the Gastrocnemius Muscle in Chicken

Disuse muscle atrophy is identified as the physiological, biochemical, morphological, and functional changes during restricted movement, immobilization, or weightlessness. Although its internal mechanism has been extensively studied in mammals and was thought to be mainly related to oxidative stress, it was unclear whether it behaved consistently in non-mammals such as chickens. In this study, we tried to construct a disuse atrophy model of the gastrocnemius muscle in chickens by limb immobilization, and collected the gastrocnemius muscles of the fixed group and the control group for RNA sequencing. Through analysis of muscle loss, HE staining, immunohistochemistry, and oxidative stress level, we found that limb immobilization could lead to loss of muscle mass, decrease in muscle fiber diameter, decrease in the proportion of slow muscle fibers, and increase in the proportion of fast muscle fibers, and also cause elevated levels of oxidative stress. In addition, a total of 565 different expression genes (DEGs) were obtained by RNA sequencing, which was significantly enriched in the biological processes such as cell proliferation and apoptosis, reactive oxygen species metabolism, and fast and slow muscle fiber transformation, and it showed that the FOXO signaling pathway, closely related to muscle atrophy, was activated. In brief, we initially confirmed that limb immobilization could induce disuse atrophy of skeletal muscle, and oxidative stress was involved in the process of disuse muscle atrophy.

Secreted Protein Acidic and Rich in Cysteine as an Exercise-Induced Gene: Towards Novel Molecular Therapies for Immobilization-Related Muscle Atrophy in Elderly Patients

Long periods of immobilization, among other etiologies, would result is muscle atrophy. Exercise is the best approach to reverse this atrophy. However, the limited or the non-ability to perform the required physical activity for such patients and the limited pharmacological options make developing novel therapeutic approaches a necessity. Within this context, secreted protein acidic and rich in cysteine (SPARC) has been characterized as an exercise-induced gene. Whereas the knock-out of this gene leads to a phenotype that mimics number of the ageing-induced and sarcopenia-related changes including muscle atrophy, overexpressing SPARC in mice or adding it to muscular cell culture produces similar effects as exercise including enhanced muscle mass, strength and metabolism. Therefore, this piece of writing aims to provide evidence supporting the potential use of SPARC/SPARC as a molecular therapy for muscle atrophy in the context of immobilization especially for elderly patients.

Cardiac Rehabilitation in Advanced aGE after PCI for acute coronary syndromes: predictors of exercise capacity improvement in the CR-AGE ACS study

BACKGROUND

The positive effect of cardiac rehabilitation (CR) on outcomes after acute coronary syndromes (ACS) is established. Nevertheless, enrollment rates into CR programs remain low, although ACS carry a high risk of functional decline particularly in the elderly.

AIM

We aimed to determine if a multidisciplinary CR improves exercise capacity in an older population discharged after ACS systematically treated with PCI.

METHODS

CR-AGE ACS is a prospective, single-center, cohort study. All patients aged 75+ years consecutively referred to Cardiac Rehabilitation outpatient Unit at Careggi University Hospital, were screened for eligibility. Moderate/severe cognitive impairment, disability in 2+ basic activities of daily living, musculoskeletal diseases, contraindication to Cardiopulmonary Exercise Test, and diseases with an expected survival < 6 months, were exclusion criteria. Participants attended a CR program, based on 5-day-per-week aerobic training sessions for 4 weeks.

RESULTS

We enrolled 253 post-ACS patients with a mean age 80.6 ± 4.4 years. After CR, 136 (56.2%) 77 (31.3%) patients obtained, respectively, at least a moderate (∆+5%) or an optimal (∆+15%) increase in VO₂peak. Baseline VO₂peak (- 1 ml/kg/min: OR 1.18; 95% CI 1.09-1.28), the number of training sessions (+1 session: OR 1.07; 95% CI 1.01-1.15), and mild-to-moderate baseline disability (yes vs. no: OR 0.22; 95% CI 0.01-0.57) were the predictors of VO₂peak changes.

CONCLUSIONS

A CR program started early after discharge from ACS produces a significant increase in exercise capacity in very old patients with mild-to-moderate post-acute physical impairment. Baseline VO₂peak, the number of training sessions, and the level of baseline disability are the independent predictors of improvement.

Relationship between skeletal bone mineral density and subjective masticatory difficulty

Background

Masticatory ability is an essential factor for sustaining quality of life and social and systemic well-being, particularly in elderly. This study aimed to reveal the association between subjective masticatory difficulty and skeletal bone mineral density (BMD).

Methods

Data from the Korean National Health and Nutrition Examination Survey, which was conducted from 2008 to 2011 were analyzed. This study included 13,092 Koreans (5656 males, 7436 females) over 50 years of age. Masticatory difficulty was evaluated based on a self-reported questionnaire. Areal BMD of the total hip, femoral neck, and lumbar spine as well as lean body mass were determined using dual-energy X-ray absorptiometry. Data about the sociodemographic characteristics, physical activity, number of teeth present, sum of decayed, missing, and filled permanent teeth (DMFT) index and Community Periodontal Index (CPI) were collected. Multivariate logistic regression analysis was conducted to analyze associations between subjective masticatory difficulty and BMD, adjusting for the confounding covariates.

Results

Significant differences were observed in the areal BMD of the total hip, femoral neck, and lumbar spine as well as lean body mass accordance with the presence of subjective masticatory difficulty in both males and females. The number of teeth, DMFT, and CPI score did not show significant differences based on the presence of self-reported satisfaction of chewing performance in both males and females. Results from multivariate logistic regression demonstrated that the subjective masticatory difficulty showed significant interactions with skeletal BMD and the associations between masticatory satisfaction and BMD of the total hip and femoral neck were more prominent in females compared to those in males.

Conclusions

The skeletal BMD, particularly areal BMD of the femoral neck was significantly associated with subjective masticatory difficulty in elderly, especially in elder females.

Sarcopenia in Children with Solid Organ Tumors: An Instrumental Era

Sarcopenia has recently been studied in both adults and children and was found to be a prognostic marker for adverse outcome in a variety of patient groups. Our research showed that sarcopenia is a relevant marker in predicting outcome in children with solid organ tumors, such as hepatoblastoma and neuroblastoma. This was especially true in very ill, high-risk groups. Children with cancer have a higher likelihood of ongoing loss of skeletal muscle mass due to a mismatch in energy intake and expenditure. Additionally, the effects of cancer therapy, hormonal alterations, chronic inflammation, multi-organ dysfunction, and a hypermetabolic state all contribute to a loss of skeletal muscle mass. Sarcopenia seems to be able to pinpoint this waste to a high degree in a new and objective way, making it an additional tool in predicting and improving outcome in children. This article focuses on the current state of sarcopenia in children with solid organ tumors. It details the pathophysiological mechanisms behind sarcopenia, highlighting the technical features of the available methods for measuring muscle mass, strength, and function, including artificial intelligence (AI)-based techniques. It also reviews the latest research on sarcopenia in children, focusing on children with solid organ tumors.

Bone Union Assessment with Computed Tomography (CT) and Statistical Associations with Mechanical or Histological Testing: A Systematic Review of Animal Studies

Objective and accurate assessment of bone union after a fracture, arthrodesis, or osteotomy is relevant for scientific and clinical purposes. Bone union is most accurately imaged with computed tomography (CT), but no consensus exists about objective assessment of bone union from CT images. It is unclear which CT-generated parameters are most suitable for bone union assessment. The aim of this review of animal studies is to find which CT-generated parameters are associated most strongly with actual bone union. Scientific databases were systematically searched. Eligible studies were studies that (1) were animal studies, (2) created a fracture, (3) assessed bone union with CT, (4) performed mechanical or histological testing as measure of actual bone union, and (5) associated CT-generated outcomes to mechanical or histological testing results. Two authors selected eligible studies and performed risk of bias assessment with QUADAS-2 tool. From 2567 studies that were screened, thirteen studies were included. Most common CT parameters that were investigated were bone mineral density, bone volume, and total callus volume. Studies showed conflicting results concerning the associations of these parameters with actual bone union. CT-assessed torsional rigidity (assessed by three studies) and callus density (assessed by two studies) showed best results. The studies investigating these two parameters reported moderate to strong associations with actual bone union. CT-assessed torsional rigidity and callus density seem the most promising parameters to represent actual bone union after a fracture, arthrodesis, or osteotomy.Prospero trial registration number: CRD42020164733.

Cell-Free Fat Extract Prevents Tail Suspension–Induced Bone Loss by Inhibiting Osteocyte Apoptosis

Introduction: As the space field has developed and our population ages, people engaged in space travel and those on prolonged bed rest are at increasing risk for bone loss and fractures. Disuse osteoporosis occurs frequently in these instances, for which the currently available anti-osteoporosis agents are far from satisfactory and have undesirable side effects. CEFFE is a cell-free fraction isolated from nanofat that is enriched with a variety of growth factors, and we aim to investigate its potential therapeutic effects on disuse osteoporosis.

Methods: A tail suspension–induced osteoporosis model was applied in this study. Three weeks after tail suspension, CEFFE was intraperitoneally injected, and PBS was used as a control. The trabecular and cortical bone microstructures of the tibia in each group were assessed by μCT after 4 weeks of administration. Osteocyte lacunar-canalicularity was observed by HE and silver staining. In vitro, MLO-Y4 cell apoptosis was induced by reactive oxygen species (ROSUP). TUNEL staining and flow cytometry were used to detect apoptosis. CCK-8 was used to detect cell proliferation, and Western blotting was used to detect MAPK signaling pathway changes.

Results: CEFFE increased the bone volume (BV/TV) and trabecular number (Tb.N) of the trabecular bone and increased the thickness of the cortical bone. HE and silver staining results showed that CEFFE reduced the number of empty lacunae and improved the lacuna-canalicular structure. CEFFE promoted osteocyte proliferative capacity in a dose-dependent manner. CEFFE protected MLO-Y4 from apoptosis by activating the serine/threonine-selective protein kinase (ERK) signaling pathways.

Conclusion: CEFFE attenuated immobilization-induced bone loss by decreasing osteocyte apoptosis. CEFFE increased the survival of osteocytes and inhibited osteocyte apoptosis by activating the ERK signaling pathway in vitro.

The Association Between Early Versus Late Physical Therapy Initiation and Outcomes of Trauma Patients With and Without Traumatic Brain Injuries

BACKGROUND

There is a lack of literature regarding the most effective timing to initiate physical therapy (PT) among traumatically injured patients. We aim to evaluate the association between early PT/mobilization versus delayed or late PT/mobilization and clinical outcomes of trauma patients.

METHODS

A retrospective cohort analysis of an urban level-I trauma center from 2014 to 2019 was performed. Univariate analyses and multivariable logistic regression were performed with significance defined as P < 0.05.

RESULTS

A total of 11,937 patients were analyzed. Among patients without a traumatic brain injury (TBI), late PT initiation times were associated with 60% lower odds of being discharged home without services (P < 0.05), significantly increased hospital and ICU length of stay (H-LOS, ICU-LOS) (P < 0.05), and significantly higher odds of complications (VTE, pneumonia, pressure ulcers, ARDS) (P < 0.001). Among patients with a TBI, late PT initiation time had 76% lower odds of being discharged home without services (P < 0.05) and significantly longer H-LOS and ICU-LOS (P < 0.05) however did not experience significantly higher odds of complications (P > 0.05).

CONCLUSIONS

Among traumatically injured patients, early PT is associated with decreased odds of complications, shorter H-LOS and ICU-LOS, and a favorable discharge disposition to home without services. Adoption of early PT initiation/mobilization protocols and establishment of prophylactic measures against complications associated with delayed PT is critical to maximize quality of care and trauma patient outcomes. Multi-center prospective studies are needed to ascertain the impact of PT initiation times in greater detail and to minimize trauma patient morbidity.

Decoding accelerometry for classification and prediction of critically ill patients with severe brain injury

Our goal is to explore quantitative motor features in critically ill patients with severe brain injury (SBI). We hypothesized that computational decoding of these features would yield information on underlying neurological states and outcomes. Using wearable microsensors placed on all extremities, we recorded a median 24.1 (IQR: 22.8-25.1) hours of high-frequency accelerometry data per patient from a prospective cohort (n = 69) admitted to the ICU with SBI. Models were trained using time-, frequency-, and wavelet-domain features and levels of responsiveness and outcome as labels. The two primary tasks were detection of levels of responsiveness, assessed by motor sub-score of the Glasgow Coma Scale (GCSm), and prediction of functional outcome at discharge, measured with the Glasgow Outcome Scale-Extended (GOSE). Detection models achieved significant (AUC: 0.70 [95% CI: 0.53-0.85]) and consistent (observation windows: 12 min-9 h) discrimination of SBI patients capable of purposeful movement (GCSm > 4). Prediction models accurately discriminated patients of upper moderate disability or better (GOSE > 5) with 2-6 h of observation (AUC: 0.82 [95% CI: 0.75-0.90]). Results suggest that time series analysis of motor activity yields clinically relevant insights on underlying functional states and short-term outcomes in patients with SBI.

Electrically stimulated eccentric contraction during non-weight bearing knee bending exercise in the supine position increases oxygen uptake: A randomized, controlled, exploratory crossover trial

It is well known that prolonged bed rest induces muscle weakness, muscle atrophy, cardiovascular deconditioning, bone loss, a loss of functional capacity, and the development of insulin resistance. Neuromuscular electrical stimulation is anticipated to be an interventional strategy for disuse due to bed rest. A hybrid training system (HTS), synchronized neuromuscular electrical stimulation for voluntary exercise using an articular motion sensor, may increase the exercise load though bed rest. We assessed oxygen uptake or heart rate during knee bending exercise in the supine position on a bed both simultaneously combined with HTS and without HTS to evaluate exercise intensity on different days in ten healthy subjects (8 men and 2 women) by a randomized controlled crossover trial. The values of relative oxygen uptake during knee bending exercise with HTS were significantly greater than those during knee bending exercise without HTS (7.29 ± 0.91 ml/kg/min vs. 8.29 ± 1.06 ml/kg/min; p = 0.0115). That increment with HTS was a mean of 14.42 ± 13.99%. Metabolic equivalents during knee bending exercise with HTS and without HTS were 2.08 ± 0.26 and 2.39 ± 0.30, respectively. The values of heart rate during knee bending exercise with HTS were significantly greater than those during knee bending exercise without HTS (80.82 ± 9.19 bpm vs. 86.36 ± 5.50 bpm; p = 0.0153). HTS could increase exercise load during knee bending exercise which is easy to implement on a bed. HTS might be a useful technique as a countermeasure against the disuse due to bed rest, for example during acute care or the quarantine for infection prophylaxis.

Molecular and Metabolic Mechanism of Low-Intensity Pulsed Ultrasound Improving Muscle Atrophy in Hindlimb Unloading Rats

Low-intensity pulsed ultrasound (LIPUS) has been proved to promote the proliferation of myoblast C2C12. However, whether LIPUS can effectively prevent muscle atrophy has not been clarified, and if so, what is the possible mechanism. The aim of this study is to evaluate the effects of LIPUS on muscle atrophy in hindlimb unloading rats, and explore the mechanisms. The rats were randomly divided into four groups: normal control group (NC), hindlimb unloading group (UL), hindlimb unloading plus 30 mW/cm² LIPUS irradiation group (UL + 30 mW/cm²), hindlimb unloading plus 80 mW/cm² LIPUS irradiation group (UL + 80 mW/cm²). The tails of rats in hindlimb unloading group were suspended for 28 days. The rats in the LIPUS treated group were simultaneously irradiated with LIPUS on gastrocnemius muscle in both lower legs at the sound intensity of 30 mW/cm² or 80 mW/cm² for 20 min/d for 28 days. C2C12 cells were exposed to LIPUS at 30 or 80 mW/cm² for 5 days. The results showed that LIPUS significantly promoted the proliferation and differentiation of myoblast C2C12, and prevented the decrease of cross-sectional area of muscle fiber and gastrocnemius mass in hindlimb unloading rats. LIPUS also significantly down regulated the expression of MSTN and its receptors ActRIIB, and up-regulated the expression of Akt and mTOR in gastrocnemius muscle of hindlimb unloading rats. In addition, three metabolic pathways (phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism) were selected as important metabolic pathways for hindlimb unloading effect. However, LIPUS promoted the stability of alanine, aspartate and glutamate metabolism pathway. These results suggest that the key mechanism of LIPUS in preventing muscle atrophy induced by hindlimb unloading may be related to promoting protein synthesis through MSTN/Akt/mTOR signaling pathway and stabilizing alanine, aspartate and glutamate metabolism.

Factors Influencing Functional Recovery during Rehabilitation after Severe Acquired Brain Injuries: A Retrospective Analysis

Severe acquired brain injuries (sABI) represent one of the main causes of disability and limitation in social life participation that need an intensive rehabilitation approach. The purpose of this study was to identify a possible correlation between different supposed conditioning factors and the efficiency of rehabilitation interventions. In this retrospective study, data were processed regarding 44 patients admitted to a neurorehabilitation department after sABI. A significant correlation with the efficiency of the rehabilitation intervention (expressed as the variation of the Barthel score between discharge and admittance in relation to the duration of the rehabilitative hospitalization) was found for both the etiology of the brain injury (p = 0.023), the precocity of the rehabilitation treatment (p = 0.0475), the presence of a tracheal cannula (p = 0.0084) and forms of nutrition other than oral (p < 0.0001). The results of this study suggest that improving the management of the respiratory system, swallowing and nutritional aspects, and favoring an early and personalized rehabilitation treatment, can help to optimize the overall care of patients suffering from sABI, thus allowing a reduction in complications, improvement in functional recovery and ensuring a better management of economic, social and health resources.

Suppression of cancer-associated bone loss through dynamic mechanical loading

Patients afflicted with or being treated for cancer constitute a distinct and alarming subpopulation who exhibit elevated fracture risk and heightened susceptibility to developing secondary osteoporosis. Cancer cells uncouple the regulatory processes central for the adequate regulation of musculoskeletal tissue. Systemically taxing treatments to target tumors or disrupt the molecular elements driving tumor growth place considerable strain on recovery efforts. Skeletal tissue is inherently sensitive to mechanical forces, therefore attention to exercise and mechanical loading as non-pharmacological means to preserve bone during treatment and in post-treatment rehabilitative efforts have been topics of recent focus. This review discusses the dysregulation that cancers and the ensuing metabolic dysfunction that confer adverse effects on musculoskeletal tissues. Additionally, we describe foundational mechanotransduction pathways and the mechanisms by which they influence both musculoskeletal and cancerous cells. Functional and biological implications of mechanical loading at the tissue and cellular levels will be discussed, highlighting the current understanding in the field. Herein, in vitro, translational, and clinical data are summarized to consider the positive impact of exercise and low magnitude mechanical loading on tumor-bearing skeletal tissue.

Rehabilitative Exercise Training for Burn Injury

Due to improvements in acute burn care over the last few decades, most patients with severe burns (up to 90% of the total body surface) survive. However, the metabolic and cardiovascular complications that accompany a severe burn can persist for up to 3 years post injury. Accordingly, there is now a greater appreciation of the need for strategies that can hasten recovery and reduce long-term morbidity post burn. Rehabilitation exercise training (RET) is a proven effective treatment to restore lean body mass, glucose and protein metabolism, cardiorespiratory fitness, and muscle strength in burn survivors. Despite this, very few hospitals incorporate RET in programs to aid the rehabilitation of patients with severe burns. Given that RET is a safe and efficacious treatment that restores function and reduces post-burn morbidity, we propose that a long-term exercise prescription plan should be considered for all patients with severe burns. In this literature review, we discuss the current understanding of burn trauma on major organ systems, and the positive benefits of incorporating RET as a part of the long-term rehabilitation of severely burned individuals. We also provide burn-specific exercise prescription guidelines for clinical exercise physiologists.

Protective effects of Enterococcus faecium strain R30 supplementation on decreased muscle endurance under disuse in rats

NEW FINDINGS

What is the central question of this study? Does Enterococcus faecium strain R30 (R30), a new lactic acid bacterial strain for supplementation, attenuate shifts in the typology of whole muscle fibres from slow- to fast-twitch by altering the autonomic nervous system in atrophied skeletal muscles? What is the main finding and its importance? R30 supplementation may attenuate the shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres by upregulating peroxisome proliferator-activated receptor-γ coactivator-1α and activating the calcineurin-nuclear factor of activated T-cells signalling pathway, thus ameliorating the decrease in muscle endurance associated with disuse.

ABSTRACT

Enterococcus faecium strain R30 (R30), a new lactic acid bacterial strain for supplementation, was hypothesized to attenuate shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres in atrophied skeletal muscles. We further postulated that the prevention of slow-to-fast fibre shifts would suppress the decreased muscle endurance associated with atrophy. To evaluate the protective effects of R30, we analysed slow-to-fast fibre shifts and disuse-associated reduced muscle endurance. R30 was administered to rats with an acclimation period of 7 days before hindlimb unloading (HU) for 2 weeks. The composition ratio of the fibre type and the expression levels of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), calcineurin and nuclear factor of activated T-cells (NFAT) were measured. Muscle endurance was evaluated at the end of the 2-week HU period in an in situ environment. R30 supplementation suppressed the slow-to-fast fibre switch and decreased the HU-induced expression of PGC-1α proteins and the deactivation of the calcineurin-NFAT pathway. Furthermore, R30 prevented a decrease in HU-associated muscle endurance in calf muscles. These results indicate that R30 supplementation may attenuate the shifts in the typology of whole muscle fibres from slow- to fast-twitch fibres via the upregulation of PGC-1α and the activation of the calcineurin-NFAT signalling pathway, thereby ameliorating the decrease in muscle endurance associated with disuse.

Bone Health in Idiopathic Inflammatory Myopathies: Diagnosis and Management

PURPOSE OF REVIEW

This article provides an update on the most recent advances in epidemiology, pathogenesis, diagnostic procedures, and therapeutic approaches for myositis-associated bone diseases, such as osteoporosis and bone fractures.

RECENT FINDINGS

In the recent years, several studies showed that osteoporosis and consequent fractures are a common and frequently underestimated complication in patients with idiopathic inflammatory myopathies (IIM). In younger patients, asymptomatic fractures might present in the early phase of the disease which could increase the risk of development of further fractures. High-risk patients could be selected with early application of combined diagnostic procedures, such as fracture risk scores with steroid dose adjustments and imaging. Recent advances might help clinicians from different fields of medicine in the early recognition and management of myositis-associated osteoporosis, which will potentially improve the quality of life of patients with IIM.

The Physiology Associated With "Bed Rest" and Inactivity and How It May Relate to the Veterinary Patient With Spinal Cord Injury and Physical Rehabilitation

In the twentieth century, bed rest was commonly prescribed by human healthcare professionals as a treatment for a variety of ailments including spinal cord injury and disease. With time, the negative impact of bed rest was recognized as a source of slow and even reduced patient healing. As treatment paradigms shifted, the utility and importance of physical rehabilitation (PR) as a critical adjunctive treatment for human patients with spinal cord injury became fully recognized. Today, standardized PR protocols exist for humans with the spinal cord disease, but the same cannot be said for our veterinary patients with spinal cord injury. The purpose of this manuscript is to discuss the effects of inactivity on the musculoskeletal system and to explore how and why PR can play a critical role in improved mobility and overall health in the veterinary patient with spinal cord injury. Research with a focus on the effects of inactivity, in the form of cage rest, for the veterinary patient with spinal cord injury is lacking.

Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review

Muscle atrophy and decline in muscle strength appear very rapidly with prolonged disuse or mechanical unloading after acute hospitalization or experimental bed rest. The current study analyzed data from short-, medium-, and long-term bed rest (5-120 days) in a pooled sample of 318 healthy adults and modeled the mathematical relationship between muscle strength decline and atrophy. The results show a logarithmic disuse-induced loss of strength and muscle atrophy of the weight-bearing knee extensor muscles. The greatest rate of muscle strength decline and atrophy occurred in the earliest stages of bed rest, plateauing later, and likely contributed to the rapid neuromuscular loss of function in the early period. In addition, during the first 2 wk of bed rest, muscle strength decline is much faster than muscle atrophy: on day 5, the ratio of muscle atrophy to strength decline as a function of bed rest duration is 4.2, falls to 2.4 on day 14, and stabilizes to a value of 1.9 after ∼35 days of bed rest. Positive regression revealed that ∼79% of the muscle strength loss may be explained by muscle atrophy, while the remaining is most likely due to alterations in single fiber mechanical properties, excitation-contraction coupling, fiber architecture, tendon stiffness, muscle denervation, neuromuscular junction damage, and supraspinal changes. Future studies should focus on neural factors as well as muscular factors independent of atrophy (single fiber excitability and mechanical properties, architectural factors) and on the role of extracellular matrix changes. Bed rest results in nonuniform loss of isometric muscle strength and atrophy over time, where the magnitude of change was greater for muscle strength than for atrophy. Future research should focus on the loss of muscle function and the underlying mechanisms, which will aid in the development of countermeasures to mitigate or prevent the decline in neuromuscular efficiency.NEW & NOTEWORTHY Our study contributes to the characterization of muscle loss and weakness processes reflected by a logarithmic decline in muscle strength induced by chronic bed rest. Acute short-term hospitalization (≤5 days) associated with periods of disuse/immobilization/prolonged time in the supine position in the hospital bed is sufficient to significantly decrease muscle mass and size and induce functional changes related to weakness in maximal muscle strength. By bringing together integrated evaluation of muscle structure and function, this work identifies that 79% of the loss in muscle strength can be explained by muscle atrophy, leaving 21% of the functional loss unexplained. The outcomes of this study should be considered in the development of daily countermeasures for preserving neuromuscular integrity as well as preconditioning interventions to be implemented before clinical bed rest or chronic gravitational unloading (e.g., spaceflights).

The effects of exposure to microgravity and reconditioning of the lumbar multifidus and anterolateral abdominal muscles: implications for people with LBP

BACKGROUND CONTEXT

One of the primary changes in the neuromuscular system in response to microgravity is skeletal muscle atrophy, which occurs especially in muscles that maintain posture while being upright on Earth. Reduced size of paraspinal and abdominal muscles has been documented after spaceflight. Exercises are undertaken on the International Space Station (ISS) during and following space flight to remediate these effects. Understanding the adaptations which occur in trunk muscles in response to microgravity could inform the development of specific countermeasures, which may have applications for people with conditions on Earth such as low back pain (LBP).

PURPOSE

The aim of this study was to examine the changes in muscle size and function of the lumbar multifidus (MF) and anterolateral abdominal muscles (1) in response to exposure to 6 months of microgravity on the ISS and (2) in response to a 15-day reconditioning program on Earth.

DESIGN

Prospective longitudinal series.

PATIENT SAMPLE

Data were collected from five astronauts who undertook seven long-duration missions on the ISS.

OUTCOME MEASURES

For the MF muscle, measures included cross-sectional area (CSA) and linear measures to assess voluntary isometric contractions at vertebral levels L2 to L5. For the abdominal muscles, the thickness of the transversus abdominis (TrA), obliquus internus abdominis (IO) and obliquus externus abdominis (EO) muscles at rest and on contraction were measured.

METHODS

Ultrasound imaging of trunk muscles was conducted at four timepoints (preflight, postflight, mid-reconditioning, and post reconditioning). Data were analyzed using multilevel linear models to estimate the change in muscle parameters of interest across three time periods.

RESULTS

Beta-coefficients (estimates of the expected change in the measure across the specified time period, adjusted for the baseline measurement) indicated that the CSA of the MF muscles decreased significantly at all lumbar vertebral levels (except L2) in response to exposure to microgravity (L3=12.6%; L4=6.1%, L5=10.3%; p<.001), and CSAs at L3-L5 vertebral levels increased in the reconditioning period (p<.001). The thickness of the TrA decreased by 34.1% (p<.017), IO decreased by 15.4% (p=.04), and the combination of anterolateral abdominal muscles decreased by 16.2% (p<.001) between pre- and postflight assessment and increased (TrA<0.008; combined p=.035) during the postreconditioning period. Results showed decreased contraction of the MF muscles at the L2 (from 12.8% to 3.4%; p=.007) and L3 (from 12.2% to 5%; p=.032) vertebral levels following exposure to microgravity which increased (L2, p=.046) after the postreconditioning period. Comparison with preflight measures indicated that there were no residual changes in muscle size and function after the postreconditioning period, apart from CSA of MF at L2, which remained 15.3% larger than preflight values (p<.001).

CONCLUSIONS

In-flight exercise countermeasures mitigated, but did not completely prevent, changes in the size and function of the lumbar MF and anterolateral abdominal muscles. Many of the observed changes in size and control of the MF and abdominal muscles that occurred in response to prolonged exposure to microgravity paralleled those seen in people with LBP or exposed to prolonged bed rest on Earth. Daily individualized postflight reconditioning, which included both motor control training and weight-bearing exercises with an emphasis on retraining strength and endurance to re-establish normal postural alignment with respect to gravity, restored the decreased size and control of the MF (at the L3-L5 vertebral levels) and anterolateral abdominal muscles. Drawing parallels between changes which occur to the neuromuscular system in microgravity and which exercises best recover muscle size and function could help health professionals tailor improved interventions for terrestrial populations. Results suggested that the principles underpinning the exercises developed for astronauts following prolonged exposure to microgravity (emphasizing strength and endurance training to re-establish normal postural alignment and distribution of load with respect to gravity) can also be applied for people with chronic LBP, as the MF and anterolateral abdominal muscles were affected in similar ways in both populations. The results may also inform the development of new astronaut countermeasures targeting the MF and abdominal muscles.

Heterogeneous role of integrins in fibroblast response to small cyclic mechanical stimulus generated by a nanoporous gold actuator

It is important to understand the effects of mechanical stimulation on cell behaviors for homeostasis. Many studies have been performed on cell responses to mechanical stimuli, but the mechanosensing mechanism is still under debate. In the present study, experiments employing molecular dynamics (MD) simulations concerning the effects of cyclic mechanical stimulus on cell proliferation were performed based on the hypothesis that mechanosensing depends on integrin types. We used a nanoporous gold (NPG) actuator to prevent transfer of a mechanical stimulus via molecules other than integrins. Surprisingly, a small cyclic strain of only 0.5% enhanced the proliferation of fibroblasts. α₅β₁ and α_vβ₃ integrins showed high sensitivity to the mechanical stimulus, whereas α₁β₁ and α₂β₁ integrins exhibited low mechanosensitivity. The MD simulations showed that different conformational changes of the integrin headpiece induced by binding to the ECM led to a difference in mechanosensitivity between αI and αI-less integrin types. Thus, the present study provides evidence to support the hypothesis and suggests the mechanism for the heterogeneous roles of integrins in mechanosensing.

Chiropractic Nimmo Receptor-Tonus Technique and McKenzie Self-Therapy Program in the Management of Adjacent Segment Disease: A Case Report

Objective

The objective of the present study objective was to describe adjacent segment disease (ASD) from a chiropractic management prospective and subsequently to stimulate further research into the chiropractic therapeutic effects on such cases and to contribute to chiropractic literature.

Clinical Features

A 44-year-old woman had a history of lumbar stabilization revision operation by pedicle screw fixation for spondylolisthesis. Her intractable back pain episodes, which were diagnosed as ASD, began shortly after this surgery. At presentation, she was taking pregabalin 75 mg 2 times a day for postoperative neuropathic pain without any pain relief. Clinical testing revealed myofascial tender points reproducing the pain.

Intervention and Outcome

After taking the case history and performing a physical examination, the patient was managed with chiropractic Nimmo receptor-tonus technique in combination with McKenzie exercises. Nimmo was applied by manually pressing on clinically relevant points for 5 to 15 seconds in 11 visits over 3 weeks. The patient by herself did McKenzie exercises 5 to 10 times a day for 10 to 12 repetitions over 2 months. After 3 weeks of therapy, visual analog scale and Oswestry Disability Index scores were improved. Furthermore, because of the amelioration of the patient's symptoms, her neurosurgeon successfully discontinued pregabalin 75 mg 2 times a day without negative consequences to care.

Conclusion

As far as the authors are aware, there is currently no published case of ASD care in chiropractic literature. Our rehabilitative management received a favorable response. It can be hypothesized that it offers a perspective that informs improved patient care.

Detraining effects after 18 months of high intensity resistance training on osteosarcopenia in older men-Six-month follow-up of the randomized controlled Franconian Osteopenia and Sarcopenia Trial (FrOST)

PURPOSE

Detraining after dedicated exercise programs might be a frequent situation in older people's exercise patterns. The aim of the present study was thus to determine the effects of 6 months of detraining after 18 months of high intensity resistance exercise (HIT-RT) on musculoskeletal outcomes in older men with sarcopenia.

METHODS

Community-dwelling men aged 72 years and older with osteosarcopenia (n = 43) were randomly assigned to an 18-month HIT-RT (EG: n = 21) or a non-training control group (CG, n = 22). After the intervention, participants of the EG stopped HIT-RT for 6 months, but continued their habitual physical activity. Study outcomes were skeletal muscle mass index, bone mineral density (BMD) at the lumbar-spine and total-hip, maximum hip/leg-extensor strength, handgrip strength and gait velocity. We applied an intention-to-treat analysis with multiple imputation.

RESULTS

Changes in the HIT-RT were much more pronounced during the detraining period compared with the CG, although this effect was only significant for skeletal muscle mass index and hip-/leg-extensor strength (p = .002 and p = .013), but not for lumbar-spine BMD (p = .068), total-hip BMD (p = .069), handgrip strength (p = .066) or gait velocity (p = .067). Apart from total-hip BMD (p = .055), handgrip strength (p = .069) and gait velocity (p = .881) values of the HIT-RT group decreased significantly during detraining. However, after 24 months, overall effects (p < .001) were still observed for skeletal muscle mass index and hip-/leg-extensor strength.

CONCLUSION

Although unable to state from which point in time relevant detraining effects emerge, we conclude that health care providers should focus on continuous rather than intermitted exercise programs for older people. Clinical trial number: clinicalTrials.gov: NCT03453463; NCT04444661.

COVID-19: Short and Long-Term Effects of Hospitalization on Muscular Weakness in the Elderly

The COVID-19 pandemic has recently been the cause of a global public health emergency. Frequently, elderly patients experience a marked loss of muscle mass and strength during hospitalization, resulting in a significant functional decline. This paper describes the impact of prolonged immobilization and current pharmacological treatments on muscular metabolism. In addition, the scientific evidence for an early strength intervention, neuromuscular electrical stimulation or the application of heat therapy during hospitalization to help prevent COVID-19 functional sequels is analyzed. This review remarks the need to: (1) determine which potential pharmacological interventions have a negative impact on muscle quality and quantity; (2) define a feasible and reliable pharmacological protocol to achieve a balance between desired and undesired medication effects in the treatment of this novel disease; (3) implement practical strategies to reduce muscle weakness during bed rest hospitalization and (4) develop a specific, early and safe protocol-based care of functional interventions for older adults affected by COVID-19 during and after hospitalization.

Using Electrical Impedance Myography as a Biomarker of Muscle Deconditioning in Rats Exposed to Micro- and Partial-Gravity Analogs

As astronauts prepare to undertake new extra-terrestrial missions, innovative diagnostic tools are needed to better assess muscle deconditioning during periods of weightlessness and partial gravity. Electrical impedance myography (EIM) has been used to detect muscle deconditioning in rodents exposed to microgravity during spaceflight or using the standard ground-based model of hindlimb unloading via tail suspension (HU). Here, we used EIM to assess muscle changes in animals exposed to two new models: hindlimb suspension using a pelvic harness (HLS) and a partial weight-bearing (PWB) model that mimics partial gravity (including Lunar and Martian gravities). We also used a simple needle array electrode in lieu of surface or ex vivo EIM approaches previously employed. Our HLS results confirmed earlier findings obtained after spaceflight and tail suspension. Indeed, one EIM measure (i.e., phase-slope) that was previously reported as highly sensitive, was significantly decreased after HLS (day 0: 14.60 ± 0.97, day 7: 11.03 ± 0.81, and day 14: 10.13 ± 0.55 | Deg/MHz|, p < 0.0001), and was associated with a significant decrease in muscle grip force. Although EIM parameters such as 50 kHz phase, reactance, and resistance remained variable over 14 days in PWB animals, we identified major PWB-dependent effects at 7 days. Moreover, the data at both 7 and 14 days correlated to previously observed changes in rear paw grip force using the same PWB model. In conclusion, our data suggest that EIM has the potential to serve as biomarker of muscle deconditioning during exposure to both micro- and partial- gravity during future human space exploration.

Effects of Testosterone on Serum Concentrations, Fat-free Mass, and Physical Performance by Population: A Meta-analysis

Testosterone (T) administration (TA) increases serum T and fat-free mass (FFM). Although TA-mediated increases in FFM may enhance physical performance, the data are largely equivocal, which may be due to differences in study populations, the magnitude of change in serum T and FFM, or the performance metrics. This meta-analysis explored effects of TA on serum T, FFM, and performance. Associations between increases in serum T and FFM were assessed, and whether changes in serum T or FFM, study population, or the performance metrics affected performance was determined. A systematic review of double-blind randomized trials comparing TA versus placebo on serum T, FFM, and performance was performed. Data were extracted from 20 manuscripts. Effect sizes (ESs) were assessed using Hedge's g and a random effects model. Data are presented as ES (95% confidence interval). No significant correlation between changes in serum T and FFM was observed (P = .167). Greater increases in serum T, but not FFM, resulted in larger effects on performance. Larger increases in testosterone (7.26 [0.76-13.75]) and FFM (0.80 [0.20-1.41]) were observed in young males, but performance only improved in diseased (0.16 [0.05-0.28]) and older males (0.19 [0.10-0.29]). TA increased lower body (0.12 [0.07-0.18]), upper body (0.26 [0.11-0.40]), and handgrip (0.13 [0.04-0.22]) strength, lower body muscular endurance (0.38 [0.09-0.68]), and functional performance (0.20 [0.00-0.41]), but not lower body power or aerobic endurance. TA elicits increases in serum T and FFM in younger, older, and diseased males; however, the performance-enhancing effects of TA across studies were small, observed mostly in muscular strength and endurance, and only in older and diseased males.

Nuclear mechanosensing: mechanism and consequences of a nuclear rupture

The physical connections between the cytoskeletal system and the nucleus provide a route for the nucleus to sense the mechanical stress both inside and outside of the cell. Failure to withstand such stress leads to nuclear rupture, which is observed in human diseases. In this review, we will go through the recent findings and our current understandings of nuclear rupture. Starting with the triggers of nuclear rupture, including the aberrant nuclear lamina composition and the elevated actomyosin contractility. We will also discuss the role of ESCRT-III in nuclear rupture repair and the biological consequences of nuclear rupture, including the negative impacts on cellular compartmentalization, DNA damage, and cellular differentiation. Recent studies on nuclear rupture provide further insights into the direct mechanistic link between nuclear rupture and several pathological conditions. Such knowledge can guide us in developing potential therapeutic solutions for the patients.

Nutritional interventions during bed rest and spaceflight: prevention of muscle mass and strength loss, bone resorption, glucose intolerance, and cardiovascular problems

Bed rest is necessary for many medical conditions but also used as a ground-based model for space flight (along with head-down tilt to simulate fluid shifts in microgravity). The purpose of this review is to examine nutritional interventions during bed rest and spaceflight for prevention of muscle and strength loss, glucose intolerance, bone resorption, and cardiovascular problems. Increased dietary protein intake and supplementation with amino acids, β-hydroxy-β-methylbutyrate, or cofactors with antioxidant properties are effective for ameliorating bed rest-induced loss of muscle mass and strength. Previous literature involving bed rest with dietary protein/amino acid supplementation had mixed findings, likely due to differences in dosage. Although high protein intake in some studies prevents bed rest-induced muscle loss, it also increases bone resorption. High calcium intake and vitamin D supplementation are not beneficial for preventing bone degradation during bed rest or spaceflight. Very few studies investigated countermeasures to prevent glucose intolerance and cardiovascular risks during bed rest/spaceflight. Low-glycemic index diets might be beneficial for the prevention of bed rest-induced glucose intolerance and cardiovascular problems. The present evidence warrants additional studies on the exact threshold of protein/amino acid intake to prevent the loss of muscle mass and strength during bed rest/spaceflight specifically to maintain the beneficial effects of proteins on muscle mass and function without increasing bone resorption. Furthermore, it is suggested to study the effects of vitamin K supplementation on bone health during bed rest/spaceflight and determine the role of long-term low-glycemic index diets on glucose regulation and cardiovascular health during extended bed rest.

Falls and Cancer

Falls among older people are common and are associated with substantial morbidity, mortality and healthcare costs. Increasingly cancer is becoming a disease of older people and fall rates are higher in elders living with cancer. Cancer and its treatments potentiate important risk factors for falls, including muscle weakness, poor balance, proprioception, cognitive impairment and functional disability. Sarcopenia refers to the progressive deterioration in muscle strength, mass and quality with ageing. Chronic conditions and cancer amplify this decline and are associated with a greater negative effect on function. Age-related impairments of lower limb neurological function are commonly exacerbated by neurotoxic chemotherapy, resulting in gait and balance deficits. Postural instability and falls erode confidence and result in a negative cycle of diminishing activity levels, further deconditioning and a higher risk of further falls. Cancer-related fatigue, sleep and mood disturbances compound this progressive frailty, further worsening treatment tolerance and outcomes. Cognitive impairment is a potent risk factor for falling and is frequently associated with gait abnormalities. The well-recognised effects of cancer treatment on working memory, attention, processing speed and executive function are often apparent (when their presence is sought) before treatment and may be as much the result of the cancer itself as they are 'chemo brain'. Structured exercise programmes focusing on progressively challenging strength and balance training are of proven benefit in falls prevention. Regular aerobic exercise accrues additional benefits in improved cardiorespiratory resilience and concomitant positive effects on treatment tolerance. Increased activity levels positively influence cognition, mood and foster an improved sense of well-being. Simple, practicable clinic-based tests of physical functioning, cognition and neurological function can help to identify those at high risk of falls and functional decline. The use of such instruments can aid judicious treatment planning and identify those most likely to benefit from more detailed specialist comprehensive geriatric assessment.

The Vascular Side of Chronic Bed Rest: When a Therapeutic Approach Becomes Deleterious

The interplay between chronic constraint and advanced aging on blood flow, shear-rate, vascular function, nitric oxide (NO)-bioavailability, microcirculation, and vascular inflammation factors is still a matter of debate. Ninety-eight individuals (Young, n = 28, 23 ± 3 yrs; Old, n = 36, 85 ± 7 yrs; Bedridden, n = 34, 88 ± 6 yrs) were included in the study. The bedridden group included old individuals chronically confined to bed (3.8 ± 2.3 yrs). A blood sample was collected and analyzed for plasma nitrate, and vascular inflammatory markers. Hyperemic response (∆peak) during the single passive leg movement (sPLM) test was used to measure vascular function. Skeletal muscle total hemoglobin was measured at the vastus lateralis during the sPLM test, by means of near infrared spectroscopy (NIRS). Bedridden subjects revealed a depletion of plasma nitrates compared with Old (−23.8%) and Young (−31.1%). Blood flow was lower in the Bedridden in comparison to Old (−20.1%) and Young (−31.7%). Bedridden presented lower sPLM ∆peak compared Old (−72.5%) and the Young (−83.3%). ∆peak of NIRS total hemoglobin was lower in the Bedridden compared to that in the Young (−133%). All vascular inflammatory markers except IL-6 were significantly worse in the Bedridden compared to Old and Young. No differences were found between the Old and Young in inflammatory markers. Results of this study confirm that chronic physical constraint induces an exacerbation of vascular disfunction and differential regulation of vascular-related inflammatory markers. The mechanisms involved in these negative adaptations seems to be associated with endothelial dysfunction and consequent diminished NO-bioavailability likely caused by the reduced shear-rate consequential to long-term reduction of physical activity.

Quantification of an Exercise Rehabilitation Program for Severely Burned Children: The Standard of Care at Shriners Hospitals for Children®-Galveston

Currently, there are no clear guidelines for the implementation of rehabilitative exercise training (RET) in burned individuals. Therefore, we quantified the training logs for exercise intensity, frequency, and duration of 6 weeks of this program to develop a basic framework for outpatient RET in patients recovering from severe burns. Thirty-three children (11 female, [mean ± SD] 12 ± 3 years, 145 ± 18 cm, 40 ± 11 kg, 49 ± 31 BMI percentile) with severe burns (49 ± 15% total body surface area burned, with 35 ± 22% third-degree burns) completed our 6-week resistance and aerobic exercise training program. Cardiorespiratory fitness (peak VO2), strength, power, and lean body mass (LBM) were measured before and after RET. Outcome measures were analyzed as a relative percentage of values in age- and sex-matched nonburned children (11 female, 12 ± 3 years, 154 ± 20 cm, 49 ± 22 kg, 56 ± 25 BMI percentile). At discharge, burned children had lower LBM (77% of age-sex-matched nonburn values), peak torque (53%), power (62%), and cardiorespiratory fitness (56%). After 6 weeks of training, LBM increased by 5% (82% of nonburn values), peak torque by 18% (71%), power by 20% (81%), and cardiorespiratory fitness by 18% (74%; P < .0001 for all). Quantification of data in exercise training logs suggested that physical capacity can be improved by aerobic exercise training performed at five metabolic equivalents (>70% of peak VO2) at least 3 days/week and 150 minutes/week and by resistance training performed at volume loads (reps × sets × weight) of 131 kg for the upper body and 275 kg for the lower body for 2 days/week. We present for the first time the quantification of our RET and provide clear exercise prescription guidelines specific to children with severe burn injury.

Strength and Cardiorespiratory Exercise Rehabilitation for Severely Burned Patients During Intensive Care Units: A Survey of Practice

Minimizing the deconditioning of burn injury through early rehabilitation programs (RP) in the intensive care unit (ICU) is of importance for improving the recovery time. The aim of this study was to assess current standard of care (SOC) for early ICU exercise programs in major burn centers. We designed a survey investigating exercise RP on the ICU for burn patients with >30% total burned surface area. The survey was composed of 23 questions and submitted electronically via SurveyMonkey® to six major (pediatric and adult) burn centers in Texas and California. All centers responded and reported exercise as part of their RP on the ICU. The characteristics of exercises implemented were not uniform. All centers reported to perform resistive and aerobic exercises but only 83% reported isotonic and isometric exercises. Determination of intensity of exercise varied with 50% of centers using patient tolerance and 17% using vital signs. Frequency of isotonic, isometric, aerobic, and resistive exercise was reported as daily by 80%, 80%, 83%, and 50% of centers, respectively. Duration for all types of exercises was extremely variable. Mobilization was used as a form of exercise by 100% of burn centers. Our results demonstrate that although early RP seem to be integral during burn survivor's ICU stay, no SOC exists. Moreover, early RP are inconsistently administered and large variations exist in frequency, intensity, duration, and type of exercise. Thus, future prospective studies investigating the various components of exercise interventions are needed to establish a SOC and determine how and if early exercise benefits the burn survivor.

Decreased mandibular cortical bone quality after botulinum toxin injections in masticatory muscles in female adults

This study aimed to clarify how masticatory muscle atrophy induced by botulinum toxin (BTX) injection affects cortical bone quality of the mandible using 3D modeling technology. A total of 39 young (26.9 ± 6.0 years) and 38 post-menopausal (55.3 ± 6.3 years) females were included. Computed tomography (CT) images were obtained before and after 12 months of treatment. Predictor variables were application of a stabilization splint, and/or two times of BTX injection in the bilateral temporalis and masseter muscles within a six-month interval. Outcome variables were changes in average Hounsfield units (HU) and cortical thickness of region of interest (ROI). 3D mandibular models were reconstructed using CT images, and models were used to calculate average HU and cortical thickness of ROIs, including inferior half of the lateral surface of ascending ramus, coronoid process, and temporomandibular joint condyle. Cortical bone quality at muscle insertion site was influenced by decreased muscle thickness but seemed not to be affected by decreased functional loading. Reduced functional loading seemed to influence cortical bone quality of the condyles. These effects were more remarkable in post-menopausal females. Hence, decreased masticatory muscle thickness may lead to alterations of the mandibular cortical structures, especially in post-menopausal females.

Early Mobility in the Intensive Care Unit: Evidence, Barriers, and Future Directions

Early mobility is an element of the ABCDEF bundle designed to improve outcomes such as ventilator-free days and decreased length of stay. Evidence indicates that adherence to an early mobility protocol can prevent delirium and reduce length of stay in the intensive care unit and the hospital and may decrease length of stay in a rehabilitation facility. Yet many barriers exist to implementing early mobility effectively, including patient acuity, uncertainty about when to start mobilizing the patient, staffing and equipment needs, increased costs, and limited nursing time. Implementation of early mobility requires interdisciplinary collaboration, commitment, and tools that facilitate mobility and prevent injury to nurses. This article focuses on aspects of care that can affect patient outcomes, such as preventing delirium, reducing sedation, monitoring the patient's ability to wean from the ventilator, and encouraging early mobility. It also addresses the effects of immobility as well as challenges in achieving mobility and how to overcome them.

Changes in Provider Perceptions Regarding Early Mobility in the PICU

OBJECTIVES

Early mobility in the PICU is safe and feasible. However, PICUs continue to meet barriers to implementing early mobility. PICU providers were surveyed before and after initiating an early mobility protocol to determine perceived barriers and continued challenges in performing early mobility.

DESIGN

This single-center prospective study surveyed PICU providers regarding 26 potential barriers to early mobility using a five-point Likert scale. A survey was distributed 1 month prior to and 6 months after beginning an early mobility protocol.

SETTING

Free-standing academic tertiary care children's hospital.

SUBJECTS

PICU providers of various professions.

INTERVENTIONS

Implementation of PICU-wide early mobility protocol.

MEASUREMENTS AND MAIN RESULTS

Paired pre- and post-early mobility protocol implementation surveys from 97 providers were compared. System-based barriers decreased after implementation of the early mobility protocol, such as lack of guidelines (75-20%; p < 0.01), inadequate training (74-33%; p < 0.01), lack of early mobility orders (72-30%; p < 0.01), and delayed recognition of early mobility candidates (68-35%; p < 0.01). Difficulty coordinating early mobility sessions, although significantly decreased, still remained a concern for 66% of providers in the postsurvey. Lack of resources, specifically staff (85-82%; p = 0.68) and equipment (67-60%; p = 0.36), also remained significant barriers. Presence of an endotracheal tube was a barrier for only 29% of providers' post-early mobility protocol, compared with 69% prior (p < 0.01). Clinical instability remained a top concern (82-79%; p = 0.63) as well as agitation (74-67%; p = 0.23). Day shift providers, with more early mobility exposure, perceived fewer barriers compared with night shift providers. Ninety percentage of post-early mobility survey participants felt that early mobility positively impacted their patients.

CONCLUSIONS

Implementation of an early mobility protocol significantly changed provider perceptions regarding barriers to early mobility. Certain factors, such as staff availability, coordination difficulty, equipment shortage, and patient clinical factors, continue to be significant challenges to early mobility in the PICU population.

Advances and applications of environmental stress adaptation research

Evolution has produced animals that survive extreme fluctuations in environmental conditions including freezing temperatures, anoxia, desiccating conditions, and prolonged periods without food. For example, the wood frog survives whole-body freezing every winter, arresting all gross physiological functions, but recovers functions upon thawing in the spring. Likewise, many small mammals hibernate for months at a time with minimal metabolic activity, organ perfusion, and movement, yet do not suffer significant muscle atrophy upon arousal. These conditions and the biochemical adaptations employed to deal with them can be viewed as Nature's answer to problems that humans wish to answer, particularly in a biomedical context. This review focuses on recent advances in the field of animal environmental stress adaptation, starting with an emphasis on new areas of research such as epigenetics and microRNA. We then examine new and emerging technologies such as genome editing, novel sequencing applications, and single cell analysis and how these can push us closer to a deeper understanding of biochemical adaptation. Next, evaluate the potential contributions of new high-throughput technologies (e.g. next-generation sequencing, mass spectrometry proteomics) to better understanding the adaptations that support these extreme phenotypes. Concluding, we examine some of the human applications that can be gained from understanding the principles of biochemical adaptation including organ preservation and treatments for conditions such as ischemic stroke and muscle disuse atrophy.

Factors Associated with Functional Disability Among Lebanese Elderly Living in Rural Areas: Role of Polypharmacy, Alcohol Consumption, and Nutrition-based on the Aging and Malnutrition in Elderly Lebanese (AMEL) Study

The objective is to describe disability risk factors in Lebanese elderly living in rural settings, focusing on the role of polypharmacy, alcohol consumption, and nutrition. The Aging and Malnutrition in Elderly Lebanese study, a cross-sectional population-based one (April 2011–April 2012), included 1200 individuals aged ≥65 years from 24 Lebanese rural districts. The results showed that 288 (24%) were disabled and 287 (23.9%) exposed to polypharmacy. More disabled participants were found among patients exposed to polypharmacy (40.8%) than those who were not (18.8%). Major classes associated with disability were “Parkinson” and “Alzheimer” medications, with “alcohol consumption” being responsible for a major interaction with medications. Chronic diseases, nutrition, and socioeconomic status also had a large effect on disability. Skin ulcer (ORa = 8.569; CI 5.330–14.823), followed by dementia (ORa = 3.667; CI 1.167–8.912), and anti-gout drugs (ORa = 3.962; CI 1.290–7.622) were found to be significantly associated with increased odds of disability the most. Many factors are associated with disability among elderly, including polypharmacy and the association of medications with alcohol. Counseling of the elderly caregivers is warranted.