The Aging Muscle in Experimental Bed Rest: A Systematic Review and Meta-Analysis

Identifying factors associated with post-hospital falls in older patients: a territory-wide cohort study

OBJECTIVES

Post-hospital falls impose a substantial healthcare burden on older adults, yet contributing factors remain inadequately examined. This study aimed to investigate underinvestigated factors associated with post-hospital falls.

STUDY DESIGN

Retrospective territory-wide cohort study.

METHODS

We examined the electronic medical records of patients aged ≥65 who were discharged from public hospitals in Hong Kong (2007-2018). During the 12 months following discharge, participants were monitored to identify falls based on diagnosis codes or clinical notes from inpatient episodes, the emergency department (ED) visits, and death records. Falls were categorized into two groups: those only requiring ED visits and those requiring hospitalizations. Binary logistic and multinomial logistic regressions examined the associated factors for post-hospital falls and subcategories of falls, respectively.

RESULTS

Among 606,392 older patients, 28,593 (4.71%; 95% CI = 4.66%-4.77%) experienced falls within 12 months after discharge. Of those, 8438 (29.5%) only required ED visits, and 20,147 (70.5%) required hospitalizations. Discharge from non-surgical wards, length of stay over two weeks, receiving the Geriatric Day Hospital and Rehabilitation Day Program, advancing age, being female, having more comorbidities, taking more fall risk increasing drugs, previous admission for falls, and living in Hong Kong Island were associated with increased fall risk. Receiving allied health service or nurse service was associated with reduced risk. The same factors were more associated with falls requiring hospitalizations rather than falls only requiring ED visits.

CONCLUSIONS

Older patients with identified factors were particularly vulnerable to post-hospital falls leading to rehospitalizations. Fall risk assessment and tailored prevention should prioritize this group.

Usefulness of non-surgical treatment without weight bearing restriction versus surgical treatment for maintaining activities of daily living in patients with peri-prosthetic femoral fractures

PURPOSE

Non-surgical treatment without weight-bearing restriction, even in the early post-injury phase, may have a favourable effect on the activities of daily living (ADLs) in elderly patients with peri-prosthetic femoral fractures (PFFs). This study aimed to assess the effectiveness of surgical and non-surgical treatments for PFFs in terms of ADL maintenance and clinical safety.

METHODS

This retrospective cohort study included 44 patients with PFFs proximal to the stem fixation site without stem loosening. Rehabilitation with weight bearing was initiated after internal fixation of the fracture site in the surgical group (n = 12) and immediately after the injury in the non-surgical group (n = 32). Clinical and radiological outcomes, including time until the first weight-bearing exercise, time until independent walking, ADL deterioration, and bone union rate, were compared between groups. Independent risk factors for ADL deterioration were also evaluated.

RESULTS

The time until first weight-bearing exercise was shorter and the ADL deterioration rate was smaller in the non-surgical group than in the surgical group (8.8 ± 9.2 vs. 21 ± 13 days, P = 0.004; 6.2% vs. 12.5%, P = 0.04, respectively). Bone union rates were similar between groups (91% vs. 83%, P = 0.42), and aseptic loosening of the stem was not observed. Time until first weight-bearing exercise was identified as an independent risk factor for ADL deterioration (odds ratio, 1.13; 95% confidence interval, 1.01-1.26; P = 0.03).

CONCLUSION

Non-surgical treatment of PFFs proximal to the stem fixation site without stem loosening, which does not restrict early weight-bearing exercise after injury, is an effective and safe treatment procedure that maintains ADL performance in elderly patients.

Waiting for surgery after hip fracture-Health and/or economic risk?

OBJECTIVES

Waiting for surgery is a disconcerting experience. It can have a negative impact on patients' outcomes and length of stay (LOS) as driver for treatment costs. Process-optimisation may be a strategy to improve quality and cost-efficacy. The study investigates the correlation between waiting for hip fracture surgery and patient characteristics, organisational variables, outcomes, LOS, and the distribution of waiting times and LOS over time, including cost estimates. Thereby the study aims to identify the potential for organisational improvements with respect to managing the waiting time.

METHODS

Ten-year routine health data (patient characteristics and follow-up information) and process-indicators that is, waiting time and LOS from a Swiss trauma-centre were analysed retrospectively. Cost-estimates were calculated based on Swiss diagnosis related groups and daily costs to evaluate hospital revenues.

RESULTS

In total, 2572 patients aged ≥60 years with low-energy hip fractures were included. Waiting times >48 h were associated with sub-optimal outcomes. Over the years long waiting times decreased. This reduction was not reflected by a reduction in LOS which remained stable around 10 days, primarily driven by late discharge to in-patient rehabilitation. Reimbursement persisted at an average revenue in the low 4-5-digit range, depending on implant costs.

CONCLUSIONS

While there has been a reduction of waiting times, this has not translated into a reduction of LOS or potential savings in health care costs, due to the various dependencies along the patient journey. Managing waiting times may be an area for improvement, increasing cost-efficacy, especially since long waiting times are still associated with inferior outcomes and LOS.

The impact of changes in physical activity on functional recovery for older inpatients in post-acute rehabilitation units

PURPOSE

The effect of increased physical activity duration on functional recovery in older inpatients in subacute settings is not well established. This study aimed to investigate the relationship between physical activity and functional recovery in older patients receiving post-acute and subacute care.

METHODS

We analyzed cohort data of hospitalized older patients (age ≥ 65 years) in the post-acute rehabilitation units. The main outcome was functional independence measure (FIM) gain. Physical activity was measured using a triaxial accelerometer. Changes in sedentary behavior and total physical activity time from admission to discharge were measured as changes in each physical activity time. Logistic regression analysis was performed to examine the relationship between changes in physical activity and FIM gain.

RESULTS

A total of 210 patients were eligible for analysis. The mean age of the study patients was 83.6 ± 7.2 years, and 63.8% (n = 134) were female. According to the multivariate regression analysis, changes in sedentary behavior time were significantly associated with high recovery of FIM gain (odds ratio [OR] 0.996, 95% confidence interval [CI]: 0.993-1.000; p = 0.026), and changes in total physical activity time also showed a similar association (OR 1.006, 95% CI 1.000-1.011; p = 0.041).

CONCLUSION

Decreased sedentary behavior time and increased total physical activity time were significantly associated with high functional recovery in post-acute rehabilitation units. These results suggest that interventions for physical activity duration may be effective in improving activities of daily living in older post-acute and subacute patients.

Early Postoperative Functional Recovery in Older Patients With Periprosthetic Femoral Fractures: Comparison Between Cemented and Cementless Stem Revisions

Background

Early postoperative functional recovery is important in older patients with lower-extremity fractures to prevent disuse, and periprosthetic femoral fractures (PFFs) are no exception. This study aimed to compare the postoperative functional recovery in the early phase after revision for PFF with loose stems between cemented and cementless stems.

Methods

Eighteen patients with Unified Classification System type B2 PFF were included in this retrospective cohort study with a follow-up period of about 2 years. All patients underwent stem revision and were divided into 2 groups: the cemented stem group (n = 9) and the cementless stem group (n = 9). In postrevision, functional independence measure score, independent walk rate, activities of daily living recovery rate to the original level at 2 weeks postoperatively, the Beals and Tower classification for radiological status, and survival rate for readmission as endpoints were compared between the 2 groups.

Results

Patients in the cemented group recovered functional mobility earlier than in the cementless group, with higher postoperative functional independence measure functional subscale values (73 vs 50 points, P = .02), higher independent walk rate (89 vs 11%, P < .01), and more postoperative activities of daily living recovery (100% vs 44%, P = .03) at 2 weeks postoperatively. The Beals and Tower classification and survival rates were similar in both groups.

Conclusions

Revision using a cemented stem for PFF in older patients was a useful surgical procedure in terms of early postoperative functional recovery. Cemented stem revision was comparable with cementless in bone union and safety at 2 years postoperatively.

The Detrimental Effects of Bedrest: Premature Cardiovascular Aging and Dysfunction

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.

Innovations in the Assessment of Skeletal Muscle Health: A Glimpse into the Future

Skeletal muscle is the largest organ system in the human body and plays critical roles in athletic performance, mobility, and disease pathogenesis. Despite growing recognition of its importance by major health organizations, significant knowledge gaps remain regarding skeletal muscle health and its crosstalk with nearly every physiological system. Relevant public health challenges like pain, injury, obesity, and sarcopenia underscore the need to accurately assess skeletal muscle health and function. Feasible, non-invasive techniques that reliably evaluate metrics including muscle pain, dynamic structure, contractility, circulatory function, body composition, and emerging biomarkers are imperative to unraveling the complexities of skeletal muscle. Our concise review highlights innovative or overlooked approaches for comprehensively assessing skeletal muscle in vivo. We summarize recent advances in leveraging dynamic ultrasound imaging, muscle echogenicity, tensiomyography, blood flow restriction protocols, molecular techniques, body composition, and pain assessments to gain novel insight into muscle physiology from cellular to whole-body perspectives. Continued development of precise, non-invasive tools to investigate skeletal muscle are critical in informing impactful discoveries in exercise and rehabilitation science.

Skeletal muscle immobilisation-induced atrophy: mechanistic insights from human studies

Periods of skeletal muscle disuse lead to rapid declines in muscle mass (atrophy), which is fundamentally underpinned by an imbalance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). The complex interplay of molecular mechanisms contributing to the altered regulation of muscle protein balance during disuse have been investigated but rarely synthesised in the context of humans. This narrative review discusses human models of muscle disuse and the ensuing inversely exponential rate of muscle atrophy. The molecular processes contributing to altered protein balance are explored, with a particular focus on growth and breakdown signalling pathways, mitochondrial adaptations and neuromuscular dysfunction. Finally, key research gaps within the disuse atrophy literature are highlighted providing future avenues to enhance our mechanistic understanding of human disuse atrophy.

Dose-Response Relationship Between Exercise Duration and Enhanced Function and Cognition in Acutely Hospitalized Older Adults: A Secondary Analysis of a Randomized Clinical Trial

Background and Objectives

Exercise may reverse functional decline in hospitalized older adults, but the optimal duration is unclear. This study examined the potential relationship between in-hospital multicomponent exercise program duration and changes in physical function, cognition, and muscle function to maximize exercise-related health benefits in acutely hospitalized older patients.

Research Design and Methods

This secondary analysis of a multicenter randomized controlled trial examined the relationship between the duration of an in-hospital multicomponent exercise program and changes in physical function, cognition, and muscle strength in 570 acutely hospitalized older adults. Participants completed 3, 4, or 5-7 consecutive days of exercise based on the progression of their acute medical illness. The acute clinical condition of the older patients was similar across the study groups (i.e., 3/4/5-7 days) at admission. Outcomes included the Short Physical Performance Battery (SPPB) for functional capacity, Gait Velocity Test for gait speed, handgrip for muscle strength, and cognitive tests.

Results

Of the 570 patients included in the analysis, 298 were women (52.3%), and the mean (SD) age was 87.3 (4.8) years. Exercise groups increased SPPB scores compared with controls, with gains of 1.09 points after three days, 1.97 points after four days, and 2.02 points after 5-7 days (p < .001). The 4-day program showed the most significant benefit for functional capacity. Gait velocity increased by 0.11 m/s after 4 and 5-7 days (p = .032). Similar dose-response relationships were seen for handgrip strength and cognition, with 5-7 days showing more significant gains than three days (p < .05).

Discussion and Implications

Multicomponent exercise programs enhance physical and cognitive function in hospitalized older adults, regardless of exercise dosage. A 4-day program significantly boosts functional capacity, although 5-7 days improves handgrip strength and cognition, highlighting the importance of exercise dosage in countering functional decline. Implementing evidence-based inpatient exercise prescriptions can help reverse muscle weakness and improve cognitive and physical function.Clinical Trial Registration: NCT04600453.

Myths and Methodologies: Understanding the health impact of head down bedrest for the benefit of older adults and astronauts. Study protocol of the Canadian Bedrest Study

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.

Sarcopenia increases mortality risk in liver transplantation: a systematic review and meta-analysis

INTRODUCTION

Liver transplantation is an efficacious treatment option for those with liver cirrhosis. However, the prognostic role of sarcopenia in these patients is unknown. Given this background, we conducted a systematic review and meta-analysis of the impact of sarcopenia on mortality in patients listed, evaluated and undergoing liver transplantation.

EVIDENCE ACQUISITION

Several databases were searched from the inception to December 2022 for observational studies regarding sarcopenia in liver transplant and mortality. We calculated the risk of mortality in sarcopenia vs. no sarcopenia using the most adjusted estimate available and summarizing the data as risk ratios (RRs) with their 95% confidence intervals (CIs). A random-effect model was considered for all analyses.

EVIDENCE SYNTHESIS

Among 1135 studies initially considered, 33 articles were included for a total of 12,137 patients (mean age: 55.3 years; 39.4% females). Over a median of 2.6 years and after adjusting for a median of 3 covariates, sarcopenia increased the risk of mortality approximately 2-fold (RR: 2.01; 95% CI: 1.70-2.36). After accounting for publication bias, the re-calculated RR was 1.75 (95% CI: 1.49-2.06). The quality of the studies was generally low, as determined by the Newcastle Ottawa Scale.

CONCLUSIONS

Sarcopenia was significantly linked with an increased risk of mortality in patients listed, evaluated, and undergoing a liver transplantation, indicating the need of interventional studies in this special population with the main aim to reverse this potential reversible condition and decrease mortality risk.

Predictors of 2-Year Post-Discharge Mortality in Hospitalized Older Patients

BACKGROUND

Understanding prognostic factors for adverse health outcomes is clinically relevant for improving treatment decision-making processes, potentially leading to enhanced patient prognosis. This secondary analysis of a prospective observational study aimed to identify independent factors associated with 2-year post-discharge mortality in acutely hospitalized older patients.

METHODS

All-cause mortality and date of death of 115 patients (83.3 ± 6.3 years, females: n = 75, 65.2%) admitted to acute geriatric wards were determined two years after hospital discharge through telephone interviews. Potential prognostic factors measured at hospital admission included demographic and clinical characteristics, nutritional, cognitive, and psychological status, Fried frailty phenotype, functioning in activities of daily living, locomotor capacity, and 24 h in-hospital mobility and objectively measured physical activity (PA) behaviors.

RESULTS

The 2-year mortality rate was 36.7% (n = 41). Univariate and multivariate Cox proportional hazards regression models revealed that mean daily PA level (hazards ratio (HR) = 0.59, 95% confidence interval (CI) 0.90-1.00; p = 0.042), frailty (HR = 3.39, 95% CI 1.20-9.51; p = 0.020), and underweight, in contrast to overweight (HR = 3.10, 95% CI 1.07-9.01; p = 0.038), at hospital admission were independently predictive of post-discharge mortality.

CONCLUSION

PA, frailty, and underweight at hospital admission should be considered when evaluating long-term survival prognosis, establishing risk profiles, and developing personalized care pathways in acute hospital care of older adults.

Program with last minute abstracts of the Padua Days on Muscle and Mobility Medicine, 27 February - 2 March, 2024 (2024Pdm3)

During the 2023 Padua Days on Muscle and Mobility Medicine the 2024 meeting was scheduled from 28 February to 2 March 2024 (2024Pdm3). During autumn 2023 the program was expanded with Scientific Sessions which will take place over five days (in 2024 this includes February 29), starting from the afternoon of 27 February 2024 in the Conference Rooms of the Hotel Petrarca, Thermae of Euganean Hills (Padua), Italy. As per consolidated tradition, the second day will take place in Padua, for the occasion in the Sala San Luca of the Monastery of Santa Giustina in Prato della Valle, Padua, Italy. Confirming the attractiveness of the Padua Days on Muscle and Mobility Medicine, over 100 titles were accepted until 15 December 2023 (many more than expected), forcing the organization of parallel sessions on both 1 and 2 March 2024. The five days will include lectures and oral presentations of scientists and clinicians from Argentina, Austria, Belgium, Brazil, Bulgaria, Canada, Denmark, Egypt, France, Germany, Iceland, Ireland, Italy, Romania, Russia, Slovenia, Switzerland, UK and USA. Only Australia, China, India and Japan are missing from this edition. But we are confident that authors from those countries who publish articles in the PAGEpress: European Journal of Translational Myology (EJTM: 2022 ESCI Clarivate's Impact Factor: 2.2; SCOPUS Cite Score: 3.2) will decide to join us in the coming years. Together with the program established by 31 January 2024, the abstracts will circulate during the meeting only in the electronic version of the EJTM Issue 34 (1) 2024. See you soon in person at the Hotel Petrarca in Montegrotto Terme, Padua, for the inauguration scheduled the afternoon of 27 February 2024 or on-line for free via Zoom. Send us your email address if you are not traditional participants listed in Pdm3 and EJTM address books.

Mobility outcomes and associated factors of acute geriatric care in hospitalized older patients: results from the PAGER study

PURPOSE

To examine distinct mobility outcomes (locomotor capacity, physical activity, life-space mobility) of acute geriatric care (AGC) in acutely hospitalized older adults and identify predictors associated with these outcomes.

METHODS

The PAGER study was designed as a prospective observational study. Mobility outcomes of 107 hospitalized older patients (age = 83.2 ± 6.4 years, female: n = 68, 63.6%) receiving AGC were measured at hospital admission and discharge. Locomotor capacity was assessed with the Short Physical Performance Battery (SPPB), 24-h physical activity (step count) with an activity monitor, and life-space mobility with the Life-Space Assessment in Institutionalized Settings (LSA-IS). Baseline demographical, clinical, physical, cognitive, and psychological characteristics were analyzed as candidate predictors of mobility outcomes.

RESULTS

SPPB (median [interquartile range] 4.0 [2.8-5.0] pt. vs. 5.0 [3.0-6.3] pt.), step count (516 [89-1806] steps vs. 1111 [228-3291] steps), and LSA-IS total score (10.5 [6.0-15.0] pt. vs. 16.3 [12.0-24.1] pt.) significantly improved during AGC (all p < 0.001). Adjusting for baseline status, frailty was identified as an independent negative predictor of SPPB, step count, and LSA-IS at discharge (p = 0.003-0.005). Barthel Index was also independently positively associated with step count (p = 0.017) at discharge, as was the mean daily PA level with SPPB (p = 0.027) at discharge, both independent of baseline status.

CONCLUSION

AGC improves distinct mobility outcomes in hospitalized older patients. Frailty was consistently found to be an independent negative predictor of all mobility outcomes. Frailty assessment in AGC may be important to identify patients at risk for decreased treatment gains in mobility. Early PA promotion in AGC seems to be beneficial in improving patients' locomotor capacity.

Effects of short-term multicomponent exercise intervention on muscle power in hospitalized older patients: A secondary analysis of a randomized clinical trial

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.

High-protein diet with excess leucine prevents inactivity-induced insulin resistance in women

BACKGROUND AND AIMS

Muscle inactivity leads to muscle atrophy and insulin resistance. The branched-chain amino acid (BCAA) leucine interacts with the insulin signaling pathway to modulate glucose metabolism. We have tested the ability of a high-protein BCAA-enriched diet to prevent insulin resistance during long-term bed rest (BR).

METHODS

Stable isotopes were infused to determine glucose and protein kinetics in the postabsorptive state and during a hyperinsulinemic-euglycemic clamp in combination with amino acid infusion (Clamp + AA) before and at the end of 60 days of BR in two groups of healthy, young women receiving eucaloric diets containing 1 g of protein/kg per day (n = 8) or 1.45 g of protein/kg per day enriched with 0.15 g/kg per day of BCAAs (leucine/valine/isoleucine = 2/1/1) (n = 8). Body composition was determined by Dual X-ray Absorptiometry.

RESULTS

BR decreased lean body mass by 7.6 ± 0.3 % and 7.2 ± 0.8 % in the groups receiving conventional or high protein-BCAA diets, respectively. Fat mass was unchanged in both groups. At the end of BR, percent changes of insulin-mediated glucose uptake significantly (p = 0.01) decreased in the conventional diet group from 155 ± 23 % to 84 ± 10 % while did not change significantly in the high protein-BCAA diet group from 126 ± 20 % to 141 ± 27 % (BR effect, p = 0.32; BR/diet interaction, p = 0.01; Repeated Measures ANCOVA). In contrast, there were no BR/diet interactions on proteolysis and protein synthesis Clamp + AA changes in the conventional diet and the high protein-BCAA diet groups.

CONCLUSION

A high protein-BCAA enriched diet prevented inactivity-induced insulin resistance in healthy women.

Low physical activity and depression are the prominent predictive factors for falling in older adults: the Birjand Longitudinal Aging Study (BLAS)

BACKGROUND

Falling in the older adults has many irreparable consequences, including hospitalization to long-term care centers and loss of independence, depression and social isolation, financial burden, and death. The present study was conducted to estimate the incidence of falls and their associated factors among community-dwelling older adults.

METHODS

This program is a population-based prospective cohort study (≥ 60 years) in Birjand City from 2019 to 2020. A total of 1418 participants were included in the study, and 1344 participants were analyzed according to the inclusion criteria. Thirty-nine risk factors were evaluated. Basic information included demographic information, lifestyle factors, general health and medical history, and mental and functional health.

RESULT

The incidence of falls among community-dwelling older adults in the previous approximately 24 months in the present study was 9.26% in women and 2.65% in men. In the multiple Cox proportional regression model based on fall risk factors, there was a strong significant relationship between male sex (HR = 0.37, CI = 0.21 to 0.64), being physically active (HR = 0.59, CI = 0.36 to 0.96), moderate-to-severe depression (HR = 2.97, CI = 1.47 to 6.01), severe depression (HR = 3.26, CI = 1.24 to 8.54), and high risk of falls according to the TUG test (HR = 1.73, CI = 1.10 to 2.72).

CONCLUSIONS

Inactivity and depression were recognized as important factors in falls in older adults. It is recommended for older adults to have an active lifestyle to prevent falls and to prioritize the diagnosis and treatment of depression in older adults. Women as a group at higher risk should be considered in prevention programs. In addition, the use of the TUG test to identify high-risk older adults should be considered.

A single bout of prior resistance exercise attenuates muscle atrophy and declines in myofibrillar protein synthesis during bed-rest in older men

Impairments in myofibrillar protein synthesis (MyoPS) during bed rest accelerate skeletal muscle loss in older adults, increasing the risk of adverse secondary health outcomes. We investigated the effect of prior resistance exercise (RE) on MyoPS and muscle morphology during a disuse event in 10 healthy older men (65-80 years). Participants completed a single bout of unilateral leg RE the evening prior to 5 days of in-patient bed-rest. Quadriceps cross-sectional area (CSA) was determined prior to and following bed-rest. Serial muscle biopsies and dual stable isotope tracers were used to determine rates of integrated MyoPS (iMyoPS) over a 7 day habitual 'free-living' phase and the bed-rest phase, and rates of acute postabsorptive and postprandial MyoPS (aMyoPS) at the end of bed rest. Quadriceps CSA at 40%, 60% and 80% of muscle length significantly decreased in exercised (EX) and non-exercised control (CTL) legs with bed-rest. The decline in quadriceps CSA at 40% and 60% of muscle length was attenuated in EX compared with CTL. During bed-rest, iMyoPS rates decreased from habitual values in CTL, but not EX, and were significantly different between legs. Postprandial aMyoPS rates increased above postabsorptive values in EX only. The change in iMyoPS over bed-rest correlated with the change in quadriceps CSA in CTL, but not EX. A single bout of RE attenuated the decline in iMyoPS rates and quadriceps atrophy with 5 days of bed-rest in older men. Further work is required to understand the functional and clinical implications of prior RE in older patient populations. KEY POINTS: Age-related skeletal muscle deterioration, linked to numerous adverse health outcomes, is driven by impairments in muscle protein synthesis that are accelerated during periods of disuse. Resistance exercise can stimulate muscle protein synthesis over several days of recovery and therefore could counteract impairments in this process that occur in the early phase of disuse. In the present study, we demonstrate that the decline in myofibrillar protein synthesis and muscle atrophy over 5 days of bed-rest in older men was attenuated by a single bout of unilateral resistance exercise performed the evening prior to bed-rest. These findings suggest that concise resistance exercise intervention holds the potential to support muscle mass retention in older individuals during short-term disuse, with implications for delaying sarcopenia progression in ageing populations.

Environmental enrichment through virtual reality as multisensory stimulation to mitigate the negative effects of prolonged bed rest

Prolonged bed rest causes a multitude of deleterious physiological changes in the human body that require interventions even during immobilization to prevent or minimize these negative effects. In addition to other interventions such as physical and nutritional therapy, non-physical interventions such as cognitive training, motor imagery, and action observation have demonstrated efficacy in mitigating or improving not only cognitive but also motor outcomes in bedridden patients. Recent technological advances have opened new opportunities to implement such non-physical interventions in semi- or fully-immersive environments to enable the development of bed rest countermeasures. Extended Reality (XR), which covers augmented reality (AR), mixed reality (MR), and virtual reality (VR), can enhance the training process by further engaging the kinesthetic, visual, and auditory senses. XR-based enriched environments offer a promising research avenue to investigate the effects of multisensory stimulation on motor rehabilitation and to counteract dysfunctional brain mechanisms that occur during prolonged bed rest. This review discussed the use of enriched environment applications in bedridden patients as a promising tool to improve patient rehabilitation outcomes and suggested their integration into existing treatment protocols to improve patient care. Finally, the neurobiological mechanisms associated with the positive cognitive and motor effects of an enriched environment are highlighted.

The use of tensiomyography in older adults: a systematic review

Introduction: Aging of skeletal muscles results in a cascade of events negatively affecting muscle mass, strength, and function, leading to reduced mobility, increased risk of falls, disability, and loss of independence. To date, different methods are used to assess muscle mechanical function, tensiomyography (TMG) being one of them. The aim of this review was twofold: to summarize the evidence-based usefulness of tensiomyography in older adults and to establish reference values for the main tensiomyography parameters in older adults. Methods: The PubMed, Web of Science, SPORTDiscus, and tensiomyography databases were searched from inception until 25 December 2022. Studies investigating older adults (aged 60+ years) that reported tensiomyography-derived parameters such as contraction time (Tc) and/or maximal displacement (Dm) were included. Methodological quality was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Results: In total, eight studies satisfied the inclusion criteria. Tensiomyography has been used on different groups of older adults, including asymptomatic, master athletes, patients with peripheral arterial disease, and patients with end-stage knee osteoarthritis with a mean age of 71.5 ± 5.38 (55.7% male subjects). The most evaluated were leg muscles such as vastus lateralis (VL), gastrocnemius medialis (GM), and biceps femoris (BF). The present review demonstrates that tensiomyography is used to assess neuromuscular function in asymptomatic and diseased older adults. When compared to asymptomatic individuals, power master athletes, knee osteoarthritis patients, and patients diagnosed with peripheral arterial disease have the shortest Tc in BF, VL, and GM muscles, respectively. On the other hand, endurance master athletes showed the longest Tc in all three evaluated muscles. Less mobile, nursing-home residents showed higher Dm in VL and BF, while lower Dm in GM than the asymptomatic group. The knee osteoarthritis group showed the largest Dm in BF and VL while having the smallest Dm in GM. Conclusion: Tensiomyography can serve as a valuable tool for assessing neuromuscular function in older adults. The method is sensitive to muscle composition, architecture, and (pre) atrophic changes of the skeletal muscles and might be responsive to muscle quality changes in aging and diseased populations. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=402345, identifier CRD42023402345.

Low Cardiorespiratory Fitness Post-COVID-19: A Narrative Review

Patients recovering from COVID-19 often report symptoms of exhaustion, fatigue and dyspnoea and present with exercise intolerance persisting for months post-infection. Numerous studies investigated these sequelae and their possible underlying mechanisms using cardiopulmonary exercise testing. We aimed to provide an in-depth discussion as well as an overview of the contribution of selected organ systems to exercise intolerance based on the Wasserman gears. The gears represent the pulmonary system, cardiovascular system, and periphery/musculature and mitochondria. Thirty-two studies that examined adult patients post-COVID-19 via cardiopulmonary exercise testing were included. In 22 of 26 studies reporting cardiorespiratory fitness (herein defined as peak oxygen uptake-VO2peak), VO2peak was < 90% of predicted value in patients. VO2peak was notably below normal even in the long-term. Given the available evidence, the contribution of respiratory function to low VO2peak seems to be only minor except for lung diffusion capacity. The prevalence of low lung diffusion capacity was high in the included studies. The cardiovascular system might contribute to low VO2peak via subnormal cardiac output due to chronotropic incompetence and reduced stroke volume, especially in the first months post-infection. Chronotropic incompetence was similarly present in the moderate- and long-term follow-up. However, contrary findings exist. Peripheral factors such as muscle mass, strength and perfusion, mitochondrial function, or arteriovenous oxygen difference may also contribute to low VO2peak. More data are required, however. The findings of this review do not support deconditioning as the primary mechanism of low VO2peak post-COVID-19. Post-COVID-19 sequelae are multifaceted and require individual diagnosis and treatment.

Early lean mass sparing effect of high-protein diet with excess leucine during long-term bed rest in women

Muscle inactivity leads to muscle atrophy. Leucine is known to inhibit protein degradation and to promote protein synthesis in skeletal muscle. We tested the ability of a high-protein diet enriched with branched-chain amino acids (BCAAs) to prevent muscle atrophy during long-term bed rest (BR). We determined body composition (using dual energy x-ray absorptiometry) at baseline and every 2-weeks during 60 days of BR in 16 healthy young women. Nitrogen (N) balance was assessed daily as the difference between N intake and N urinary excretion. The subjects were randomized into two groups: one received a conventional diet (1.1 ± 0.03 g protein/kg, 4.9 ± 0.3 g leucine per day) and the other a high protein, BCAA-enriched regimen (1.6 ± 0.03 g protein-amino acid/kg, 11.4 ± 0.6 g leucine per day). There were significant BR and BR × diet interaction effects on changes in lean body mass (LBM) and N balance throughout the experimental period (repeated measures ANCOVA). During the first 15 days of BR, lean mass decreased by 4.1 ± 0.9 and 2.4 ± 2.1% (p < 0.05) in the conventional and high protein-BCAA diet groups, respectively, while at the end of the 60-day BR, LBM decreased similarly in the two groups by 7.4 ± 0.7 and 6.8 ± 2.4%. During the first 15 days of BR, mean N balance was 2.5 times greater (p < 0.05) in subjects on the high protein-BCAA diet than in those on the conventional diet, while we did not find significant differences during the following time intervals. In conclusion, during 60 days of BR in females, a high protein-BCAA diet was associated with an early protein-LBM sparing effect, which ceased in the medium and long term.

Motor unit dysregulation following 15 days of unilateral lower limb immobilisation

Disuse atrophy, caused by situations of unloading such as limb immobilisation, causes a rapid yet diverging reduction in skeletal muscle function when compared to muscle mass. While mechanistic insight into the loss of mass is well studied, deterioration of muscle function with a focus towards the neural input to muscle remains underexplored. This study aimed to determine the role of motor unit adaptation in disuse-induced neuromuscular deficits. Ten young, healthy male volunteers underwent 15 days of unilateral lower limb immobilisation with intramuscular electromyography (iEMG) bilaterally recorded from the vastus lateralis (VL) during knee extensor contractions normalised to maximal voluntary contraction (MVC), pre and post disuse. Muscle cross-sectional area was determined by ultrasound. Individual MUs were sampled and analysed for changes in motor unit (MU) discharge and MU potential (MUP) characteristics. VL CSA was reduced by approximately 15% which was exceeded by a two-fold decrease of 31% in muscle strength in the immobilised limb, with no change in either parameter in the non-immobilised limb. Parameters of MUP size were reduced by 11% to 24% with immobilisation, while neuromuscular junction (NMJ) transmission instability remained unchanged, and MU firing rate decreased by 8% to 11% at several contraction levels. All adaptations were observed in the immobilised limb only. These findings highlight impaired neural input following immobilisation reflected by suppressed MU firing rate which may underpin the disproportionate reductions of strength relative to muscle size. KEY POINTS: Muscle mass and function decline rapidly in situations of disuse such as bed rest and limb immobilisation. The reduction in muscle function commonly exceeds that of muscle mass, which may be associated with the dysregulation of neural input to muscle. We have used intramuscular electromyography to sample individual motor unit and near fibre potentials from the vastus lateralis following 15 days of unilateral limb immobilisation. Following disuse, the disproportionate loss of muscle strength when compared to size coincided with suppressed motor unit firing rate. These motor unit adaptations were observed at multiple contraction levels and in the immobilised limb only. Our findings demonstrate neural dysregulation as a key component of functional loss following muscle disuse in humans.

Mechanism of action and therapeutic use of bempedoic acid in atherosclerosis and metabolic syndrome

Bempedoic acid is a new cholesterol-lowering drug, which has recently received US FDA and EMA approval. This drug targets lipid and glucose metabolism as well as inflammation via downregulation of ATP-citrate lyase and upregulation of AMP-activated protein kinase (AMPK). The primary effect is the reduction of cholesterol synthesis in the liver and its administration is generally not associated to unwanted muscle effects. Suppression of hepatic fatty acid synthesis leads to decreased triglycerides and, possibly, improved non-alcoholic fatty liver disease. Bempedoic acid may decrease gluconeogenesis leading to improved insulin sensitivity, glucose metabolism, and metabolic syndrome. The anti-inflammatory action of bempedoic acid is mainly achieved via activation of AMPK pathway in the immune cells, leading to decreased plasma levels of C-reactive protein. Effects of bempedoic acid on atherosclerotic cardiovascular disease, type 2 diabetes and chronic liver disease have been assessed in randomized clinical trials but require further confirmation. Safety clinical trials in phase III indicate that bempedoic acid administration is generally well-tolerated in combination with statins, ezetimibe, or proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors to achieve low-density lipoprotein cholesterol targets. The aim of this narrative review on bempedoic acid is to explore the underlying mechanisms of action and potential clinical targets, present existing evidence from clinical trials, and describe practical management of patients.

Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA)

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

Inter-Person Differences in Isometric Coactivations of Triceps Surae and Tibialis Anterior Decrease in Young, but Not in Older Adults After 14 Days of Bed Rest

We examined activation patterns of the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), soleus (SO), and tibialis anterior (TA) muscles in eight older (58.4 ± 3.3 years) and seven young (23.1 ± 2.9 years) participants, before and after 14 days of horizontal bed rest. Visual feedback on the exerted muscle torque was provided to the participants. The discharge patterns of individual motor units (MUs) were studied in three repetitions of isometric plantar flexion at 30 and 60% of Maximum Voluntary Contraction (MVC), before, and 1 day after the 14-day bed rest, respectively. In the GL and GM muscles, the older participants demonstrated higher MU discharge rates than the young, regardless of the contraction level, both before and after the bed rest. In the TA and SO muscles, the differences between the older and young participants were less consistent. Detailed analysis revealed person-specific changes in the MU discharge rates after the bed rest. To quantify the coactivation patterns we calculated the correlation coefficients between the cumulative spike trains of identified MUs from each muscle, and measured the root mean square difference of the correlation coefficients between the trials of the same session (intra-session variability) and between different sessions (inter-session variability) in each participant (intra-person comparison) and across participants (inter-person comparison). In the intra-person comparison, the inter-session variability was higher than the intra-session variability, either before or after the bed rest. At 60% MVC torque, the young demonstrated higher inter-person variability of coactivation than the older participants, but this variability decreased significantly after the bed rest. In older participants, inter-person variability was consistently lower at 60% than at 30% MVC torque. In young participants, inter-person variability became lower at 60% than at 30% MVC torque only after the bed rest. Precaution is required when analyzing the MU discharge and coactivation patterns, as individual persons demonstrate individual adaptations to aging or bed rest.

Skeletal Muscle in Hypoxia and Inflammation: Insights on the COVID-19 Pandemic

SARS-CoV-2 infection is often associated with severe inflammation, oxidative stress, hypoxia and impaired physical activity. These factors all together contribute to muscle wasting and fatigue. In addition, there is evidence of a direct SARS-CoV-2 viral infiltration into skeletal muscle. Aging is often characterized by sarcopenia or sarcopenic obesity These conditions are risk factors for severe acute COVID-19 and long-COVID-19 syndrome. From these observations we may predict a strong association between COVID-19 and decreased muscle mass and functions. While the relationship between physical inactivity, chronic inflammation, oxidative stress and muscle dysfunction is well-known, the effects on muscle mass of COVID-19-related hypoxemia are inadequately investigated. The aim of this review is to highlight metabolic, immunity-related and redox biomarkers potentially affected by reduced oxygen availability and/or muscle fatigue in order to shed light on the negative impact of COVID-19 on muscle mass and function. Possible countermeasures are also reviewed.