Distinct effects of acute exercise and breaks in sitting on working memory and executive function in older adults: a three-arm, randomised cross-over trial to evaluate the effects of exercise with and without breaks in sitting on cognition

Effects of exercise interventions on brain-derived neurotrophic factor levels in overweight and obesity: A systematic review and meta-analysis

Background

/Objective. An explosion in global obesity epidemic poses threats to the healthcare system by provoking risks of many debilitating diseases, including cognitive dysfunction. Physical activity has been shown to alleviate the deleterious effects of obesity-associated cognitive deficits across the lifespan. Given the strong neuroprotective role of brain-derived neurotrophic factor (BDNF) and exercise training as a known modulator for its elevation, this systematic review sought to examine the strength of the association between exercise and BDNF levels in healthy people with overweight and obesity.

Methods

Six electronic databases (PubMed, MEDLINE, EMBASE, Web of Science, Ovid Nursing Database, and SPORTDiscus) were searched from their inceptions through December 2022. The primary outcome of interest was BDNF levels. Interventional studies (randomized and quasi-experimental) with English full text available were included. Risk of bias of the included studies was assessed using the Physiotherapy Evidence Database Scale. Data were extracted for meta-analyses by random-effects models.

Results

Thirteen studies (n = 750), of which 69.2% (9/13) had low risk of bias, were included. In the meta-analysis, exercise interventions had no significant effect on resting BDNF levels (standardized mean difference: -0.30, 95% CI -0.80 to 0.21, P = 0.25). Subgroup analyses also indicated no effects of age and types of control groups being compared on moderating the association.

Conclusion

To further inform the role of BDNF in obesity-related cognitive functioning, rigorous studies with larger samples of participants and raw data available were imperatively deserved.

The mitochondrial quality control system: a new target for exercise therapeutic intervention in the treatment of brain insulin resistance-induced neurodegeneration in obesity

Obesity is a major global health concern because of its strong association with metabolic and neurodegenerative diseases such as diabetes, dementia, and Alzheimer's disease. Unfortunately, brain insulin resistance in obesity is likely to lead to neuroplasticity deficits. Since the evidence shows that insulin resistance in brain regions abundant in insulin receptors significantly alters mitochondrial efficiency and function, strategies targeting the mitochondrial quality control system may be of therapeutic and practical value in obesity-induced cognitive decline. Exercise is considered as a powerful stimulant of mitochondria that improves insulin sensitivity and enhances neuroplasticity. It has great potential as a non-pharmacological intervention against the onset and progression of obesity associated neurodegeneration. Here, we integrate the current knowledge of the mechanisms of neurodegenration in obesity and focus on brain insulin resistance to explain the relationship between the impairment of neuronal plasticity and mitochondrial dysfunction. This knowledge was synthesised to explore the exercise paradigm as a feasible intervention for obese neurodegenration in terms of improving brain insulin signals and regulating the mitochondrial quality control system.

Relationship Between Physical Exercise and Cognitive Function Among Older Adults in China: Cross-Sectional Population-Based Study

BACKGROUND

The existing literature reveals several significant knowledge gaps that hinder health care providers in formulating exercise prescriptions for cognitive health.

OBJECTIVE

This study endeavors to elucidate the relationship between the level of physical activity and cognitive function in older adults in China. Moreover, it seeks to explore the associations between distinct exercise behaviors-such as exercise types, the purpose motivating engagement in exercise, the accessibility of exercise fields, and the inclination toward exercise-and cognitive function.

METHODS

Using data from the China Longitudinal Aging Social Survey (CLASS conducted in 2016, cognitive function was meticulously assessed through the modified Chinese version of the Mini-Mental State Examination, encompassing measures of orientation, memory, and calculation. Using self-report structured questionnaires, a myriad of information about physical activity during leisure time, exercise engagement, exercise intensity, primary exercise types, reasons for exercise participation, availability of sports facilities, and exercise willingness was diligently gathered. Robust ordinary least squares regression models were then used to compute coefficients along with 95% CIs.

RESULTS

A discernible inverted U-shaped trend in cognitive scores emerged as the level of physical activity surpassed the threshold of 500 metabolic equivalents of task (MET) minutes per week. Notably, individuals with a physical activity level between 500 and 999 MET minutes per week exhibited a coefficient of 0.31 (95% CI 0.09 to 0.54), those with a physical activity level between 1000 and 1499 MET minutes per week displayed a coefficient of 0.75 (95% CI 0.52 to 0.97), and those with a physical activity level above 1500 MET minutes per week demonstrated a coefficient of 0.45 (95% CI 0.23 to 0.68). Older individuals engaging in exercise at specific MET levels showcased superior cognitive function compared to their inactive counterparts. Furthermore, individuals driven by exercise motivations aimed at enhancing physical fitness and health, as well as those using sports facilities or public spaces for exercise, exhibited notably higher cognitive function scores.

CONCLUSIONS

The findings underscore the potential of exercise as a targeted intervention for the prevention and treatment of dementia or cognitive decline associated with aging in older individuals. Leveraging these insights to formulate informed exercise recommendations holds promise in addressing a significant public health challenge linked to aging populations.

Exploring the Effect of Acute and Regular Physical Exercise on Circulating Brain-Derived Neurotrophic Factor Levels in Individuals with Obesity: A Comprehensive Systematic Review and Meta-Analysis

Obesity is a major global health concern linked to cognitive impairment and neurological disorders. Circulating brain-derived neurotrophic factor (BDNF), a protein crucial for neuronal growth and survival, plays a vital role in brain function and plasticity. Notably, obese individuals tend to exhibit lower BDNF levels, potentially contributing to cognitive decline. Physical exercise offers health benefits, including improved circulating BDNF levels and cognitive function, but the specific impacts of acute versus regular exercise on circulating BDNF levels in obesity are unclear. Understanding this can guide interventions to enhance brain health and counter potential cognitive decline in obese individuals. Therefore, this study aimed to explore the impact of acute and regular physical exercise on circulating BDNF in individuals with obesity. The target population comprised individuals classified as overweight or obese, encompassing both acute and chronic protocols involving all training methods. A comprehensive search was conducted across computerized databases, including PubMed, Academic Search Complete, and Web of Science, in August 2022, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Initially, 98 studies were identified, from which 16 studies, comprising 23 trials, met the selection criteria. Substantial heterogeneity was observed for both acute (I2 = 80.4%) and long-term effects (I2 = 88.7%), but low risk of bias for the included studies. A single session of exercise increased circulating BDNF levels among obese patients compared to the control group (ES = 1.25, 95% CI = 0.19 to 2.30, p = 0.021). However, with extended periods of physical exercise, there was no significant increase in circulating BDNF levels when compared to the control group (ES = 0.49, 95% CI = -0.08 to 1.06, p = 0.089). These findings highlight the need to consider exercise duration and type when studying neurobiological responses in obesity and exercise research. The study's results have implications for exercise prescription in obesity management and highlight the need for tailored interventions to optimize neurotrophic responses. Future research should focus on elucidating the adaptive mechanisms and exploring novel strategies to enhance BDNF modulation through exercise in this population. However, further research is needed considering limitations such as the potential age-related confounding effects due to diverse participant ages, lack of sex-specific analyses, and insufficient exploration of how specific exercise parameters (e.g., duration, intensity, type) impact circulating BDNF.

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

The Effects of Simultaneous Aerobic Exercise and Video Game Training on Executive Functions and Brain Connectivity in Older Adults

OBJECTIVE

The study was designed to examine the effects of simultaneous combination of aerobic exercise and video game training on executive functions (EFs) and brain functional connectivity in older adults.

DESIGN

A four-armed, quasi-experimental study.

SETTING AND PARTICIPANTS

Community-dwelling adults aged 55 years and older.

METHODS

A total of 97 older adults were divided into one of four groups: aerobic exercise (AE), video game (VG), combined intervention (CI), and passive control (PC). Participants in intervention groups received 32 sessions of training over a 4-month period at a frequency of twice a week. EFs was evaluated using a composite score derived from a battery of neuropsychological tests. The Montreal Cognitive Assessment (MoCA) was employed to evaluate overall cognitive function, while the 6-Minute Walking Test (6MWT) was utilized to gauge physical function. Additionally, the functional connectivity (FC) of the frontal-parietal networks (FPN) was examined as a neural indicator of cognitive processing and connectivity changes.

RESULTS

In terms of EFs, both VG and CI groups demonstrated improvement following the intervention. This improvement was particularly pronounced in the CI group, with a large effect size (Hedge's g = 0.83), while the VG group showed a medium effect size (Hedge's g = 0.56). A significant increase in MoCA scores was also observed in both the VG and CI groups, whereas a significant increase in 6MWT scores was observed in the AE and CI groups. Although there were no group-level changes observed in FC of the FPN, we found that changes in FC was behaviorally relevant as increased FC was associated with greater improvement in EFs.

CONCLUSION

The study offers preliminary evidence that both video game training and combined intervention could enhance EFs in older adults. Simultaneous combined intervention may hold greater potential for facilitating EFs gains. The initial evidence for correlated changes in brain connectivity and EFs provides new insights into understanding the neural basis underlying the training gains.

Sedentary behavior and lifespan brain health

Higher levels of physical activity are known to benefit aspects of brain health across the lifespan. However, the role of sedentary behavior (SB) is less well understood. In this review we summarize and discuss evidence on the role of SB on brain health (including cognitive performance, structural or functional brain measures, and dementia risk) for different age groups, critically compare assessment approaches to capture SB, and offer insights into emerging opportunities to assess SB via digital technologies. Across the lifespan, specific characteristics of SB (particularly whether they are cognitively active or cognitively passive) potentially act as moderators influencing the associations between SB and specific brain health outcomes. We outline challenges and opportunities for future research aiming to provide more robust empirical evidence on these observations.

Physical exercise frequency and cognition: a multicenter cross-sectional cohort study

Background and aims

Dementia imposes a heavy burden on society and families, therefore, effective drug treatments, exploring and preventing factors associated with dementia, are paramount. To provide reference points for the best frequency of physical exercise (physical exercise), we investigated the association between frequency of PE and cognition in Chinese old adults.

Methods

16,181 Chinese participants aged 65 years or older were included in this study. Associations between PE and cognition were estimated multivariate logistic and linear regression analyses. Associations were further investigated across dementia subtypes (Alzheimer dementia, vascular dementia, and other types of dementia). Subgroup analyses were performed in different age groups, in populations with and without stroke, and those with and without hypertension.

Results

PE associated with dementia after adjusting for full covariates (OR: 0.5414, 95% CI: 0.4536-0.6491, p < 0.001). Exercise performed at ≥3 times/week associated with lower risk of dementia (OR: 0.4794-0.6619, all p value <0.001). PE was associated with improved cognition (β: 12851, p < 0.001), and any PE frequency contributed to cognitive improvement (p values for exercise performed ≥1 time/week were <0.001). Similar conclusions were identified when we repeated analyses in different dementia subtypes and age groups. Subgroup analyses suggested that the cognition of individuals without hypertension also benefitted from exercising 1-2 times/week (OR: 0.6168, 95% CI: 0.4379-0.8668, p = 0.005).

Conclusion

The best exercise frequency is exercising ≥3 times/week for individuals from different dementia subtypes and age groups. While for those without hypertension, PE at 1-2 times /week is also beneficial.

Exercise breaks prevent attenuation in cerebrovascular function following an acute bout of uninterrupted sitting in healthy children

The purpose of this study was to examine the effect of an acute bout of prolonged sitting with and without exercise breaks on cerebrovascular function in 7- to 13-year-old children. Forty-two children and adolescents were recruited to a crossover trial, with 15 girls (mean age 10.1 ± 2.5 years) and 16 boys (mean age 10.5 ± 1.3 years) completing the two trial conditions: SIT, uninterrupted sitting for 3 h and CYCLE, 3 h of sitting interrupted hourly with a 10-min moderate intensity exercise break. Cerebrovascular function was measured Pre and Post SIT and CYCLE from blood flow (Q ̇ ${\dot{Q}}$ ), diameter, and shear rate of the internal carotid artery (ICA) at rest and in response to CO2 . Blood velocity in the middle (MCA) and posterior (PCA) cerebral arteries was assessed at rest, during a neurovascular coupling task (NVC) and in response to CO2 . We demonstrate that SIT but not CYCLE reduced ICA cerebrovascular reactivity to CO2 (%Δ ICAQ ̇ ${\dot{Q}}$ /Δ end-tidal CO2 : SIT: Pre 5.0 ± 2.4%/mmHg to Post 3.3 ± 2.8%/mmHg vs. CYCLE: Pre 4.4 ± 2.3%/mmHg to Post 5.3 ± 3.4%/mmHg, P = 0.05) and slowed the MCA blood velocity onset response time to hypercapnia (SIT: Pre 57.2 ± 32.6 s to Post 76.6 ± 55.2 s, vs. CYCLE: Pre 64.1 ± 40.4 s to Post 52.3 ± 28.8 s, P = 0.05). There were no changes in NVC. Importantly, breaking up prolonged sitting with hourly exercise breaks prevented the reductions in cerebrovascular reactivity to CO2 and the slowed intracranial blood velocity onset response time to hypercapnia apparent with uninterrupted sitting in children. NEW FINDINGS: What is the central question of this study? What are the effects of interrupting prolonged sitting on cerebrovascular function in children? What is the main finding and its importance? Prolonged sitting results in declines in cerebrovascular reactivity, a valuable index of cerebrovascular health. Breaking up prolonged sitting with hourly 10 min exercise breaks prevented these changes. These initial findings suggest excessive sedentary behaviour does impact cerebrovascular function in childhood, but taking exercise breaks prevents declines.

Mechanisms of the Beneficial Effects of Exercise on Brain-Derived Neurotrophic Factor Expression in Alzheimer's Disease

Brain-derived neurotrophic factor (BDNF) is a key molecule in promoting neurogenesis, dendritic and synaptic health, neuronal survival, plasticity, and excitability, all of which are disrupted in neurological and cognitive disorders such as Alzheimer's disease (AD). Extracellular aggregates of amyloid-β (Aβ) in the form of plaques and intracellular aggregates of hyperphosphorylated tau protein have been identified as major pathological insults in the AD brain, along with immune dysfunction, oxidative stress, and other toxic stressors. Although aggregated Aβ and tau lead to decreased brain BDNF expression, early losses in BDNF prior to plaque and tangle formation may be due to other insults such as oxidative stress and contribute to early synaptic dysfunction. Physical exercise, on the other hand, protects synaptic and neuronal structure and function, with increased BDNF as a major mediator of exercise-induced enhancements in cognitive function. Here, we review recent literature on the mechanisms behind exercise-induced BDNF upregulation and its effects on improving learning and memory and on Alzheimer's disease pathology. Exercise releases into the circulation a host of hormones and factors from a variety of peripheral tissues. Mechanisms of BDNF induction discussed here are osteocalcin, FNDC5/irisin, and lactate. The fundamental mechanisms of how exercise impacts BDNF and cognition are not yet fully understood but are a prerequisite to developing new biomarkers and therapies to delay or prevent cognitive decline.

Physiology of sedentary behavior

Sedentary behaviors (SB) are characterized by low energy expenditure while in a sitting or reclining posture. Evidence relevant to understanding the physiology of SB can be derived from studies employing several experimental models: bed rest, immobilization, reduced step count, and reducing/interrupting prolonged SB. We examine the relevant physiological evidence relating to body weight and energy balance, intermediary metabolism, cardiovascular and respiratory systems, the musculoskeletal system, the central nervous system, and immunity and inflammatory responses. Excessive and prolonged SB can lead to insulin resistance, vascular dysfunction, shift in substrate use toward carbohydrate oxidation, shift in muscle fiber from oxidative to glycolytic type, reduced cardiorespiratory fitness, loss of muscle mass and strength and bone mass, and increased total body fat mass and visceral fat depot, blood lipid concentrations, and inflammation. Despite marked differences across individual studies, longer term interventions aimed at reducing/interrupting SB have resulted in small, albeit marginally clinically meaningful, benefits on body weight, waist circumference, percent body fat, fasting glucose, insulin, HbA1c and HDL concentrations, systolic blood pressure, and vascular function in adults and older adults. There is more limited evidence for other health-related outcomes and physiological systems and for children and adolescents. Future research should focus on the investigation of molecular and cellular mechanisms underpinning adaptations to increasing and reducing/interrupting SB and the necessary changes in SB and physical activity to impact physiological systems and overall health in diverse population groups.

The brain-derived neurotrophic factor Val66met polymorphism is associated with better attention and working memory performance and resilience to mild chronic stress

The val66met polymorphism of the brain-derived neurotrophic factor (BDNF) gene has been identified as a potential moderator for the relationship between chronic stress and executive functioning. However, whether the presence of the met allele increases cognitive vulnerability or resilience to stress has yet to be determined. Given the established effects of autonomic activity and psychological arousal on executive functioning, in the present study, 56 healthy university students completed self-report measures of chronic stress, positive arousal (vigour) and negative arousal (anxiety) and measured heart-rate variability to quantify autonomic activity. Participants then completed a cognitive test battery that measured attention, decision-making, visual learning and working memory. Regression analyses demonstrated that Val/met participants performed better on attention and working memory tasks than Val/val participants, but no differences were seen in decision-making and visual learning. Further, Val/met participants were protected from stress-related differences in attention seen in Val/val participants. Val66met was not associated with physiological or psychological arousal. This study demonstrates that val66met plays an important but selective role in cognitive performance.

Move Your Body, Boost Your Brain: The Positive Impact of Physical Activity on Cognition across All Age Groups

While the physical improvements from exercise have been well documented over the years, the impact of physical activity on mental health has recently become an object of interest. Physical exercise improves cognition, particularly attention, memory, and executive functions. However, the mechanisms underlying these effects have yet to be fully understood. Consequently, we conducted a narrative literature review concerning the association between acute and chronic physical activity and cognition to provide an overview of exercise-induced benefits during the lifetime of a person. Most previous papers mainly reported exercise-related greater expression of neurotransmitter and neurotrophic factors. Recently, structural and functional magnetic resonance imaging techniques allowed for the detection of increased grey matter volumes for specific brain regions and substantial modifications in the default mode, frontoparietal, and dorsal attention networks following exercise. Here, we highlighted that physical activity induced significant changes in functional brain activation and cognitive performance in every age group and could counteract psychological disorders and neural decline. No particular age group gained better benefits from exercise, and a specific exercise type could generate better cognitive improvements for a selected target subject. Further research should develop appropriate intervention programs concerning age and comorbidity to achieve the most significant cognitive outcomes.

Pre- and Postoperative Exercise Effectiveness in Mobility, Hemostatic Balance, and Prognostic Biomarkers in Hip Fracture Patients: A Study Protocol for a Randomized Controlled Trial

Hip fractures are a major health concern, particularly for older adults, as they can reduce life quality, mobility loss, and even death. Current evidence reveals that early intervention is recommended for endurance in patients with hip fractures. To our knowledge, preoperative exercise intervention in patients with hip fractures remains poorly researched, and no study has yet applied aerobic exercise preoperatively. This study aims to investigate the short-term benefits of a supervised preoperative aerobic moderate-intensity interval training (MIIT) program and the added effect of an 8-week postoperative MIIT aerobic exercise program with a portable upper extremity cycle ergometer. The work-to-recovery ratio will be 1-to-1, consisting of 120 s for each bout and four and eight rounds for the pre- and postoperative programs, respectively. The preoperative program will be delivered twice a day. A parallel group, single-blinded, randomized controlled trial (RCT) was planned to be conducted with 58 patients each in the intervention and control groups. This study has two primary purposes. First, to study the effect of a preoperative aerobic exercise program with a portable upper extremity cycle ergometer on immediate postoperative mobility. Second, to investigate the additional effect of an 8-week postoperative aerobic exercise program with a portable upper extremity cycle ergometer on the walking distance at eight weeks after surgery. This study also has several secondary objectives, such as ameliorating surgical and keeping hemostatic balance throughout exercise. This study may expand our knowledge of preoperative exercise effectiveness in hip fracture patients and enhance the current literature about early intervention benefits.

The Association Between Objectively-Measured Physical Activity and Cognitive Functioning in Middle-Aged and Older People Living with HIV

Middle-aged and older people living with HIV (PWH) are at higher risk for cognitive impairment and engage in lower levels of physical activity (PA) than seronegative counterparts. Research examining the association between objectively-measured PA and cognitive function in this population is scarce. This cross-sectional study examined the association between accelerometry-measured PA and cognitive functioning among 75 PWH (mean age 55.63). Light PA was the PA variable with the most consistent associations with cognition, with more minutes per week of light PA (performed in bouts of ≥ 10 min) being associated with better executive function, working memory/attention, and speed of processing performance, adjusted for age and current CD4 count. Findings suggest that although middle-aged and older PWH engage in more light than moderate-to-vigorous PA, light PA may be beneficial to cognition. Longitudinal studies are needed to understand PA dose-response associations with cognitive trajectories, cognitive domain specificity of PA effects, and underlying neural mechanisms of PA.

Influence of Sedentary Behaviour Interventions on Vascular Functions and Cognitive Functions in Hypertensive Adults-A Scoping Review on Potential Mechanisms and Recommendations

Since the workplace has become desk-based and leisure time has become dominated by digital relaxation modes, the world is moving at a pace where physical activity has become a time-bound routine. The negative effects of extended sitting are a global concern since the workforce is becoming more desk based. There is a dearth of reviews that may link the knowledge on the effects of sedentary behaviour on hypertension and its accompanying damage to the brain and blood vessels and provide a future scope for the investigations connected to the relationship between sedentary behaviour and hypertension. Methods: Based on the database search and extensive research we did, we found studies that concentrated on the adverse effects of sedentary behaviour in association with blood pressure, cognitive decline and brain damage on adults. Results: We extracted 12 articles out of 20,625. We identified the potential adverse effects of sedentary behaviour, methods to reduce sedentary behaviour and the positive changes on health due to the interventions introduced. Sedentary lifestyle has shown a decline in human health. However, the visible symptoms presented later in life makes it very important to know the areas of decline and look for ways to curb the decline or procrastinate it.

Cross-Sectional Associations of Body Adiposity, Sedentary Behavior, and Physical Activity with Hemoglobin and White Blood Cell Count

BACKGROUND

This study examined whether hemoglobin (Hb) and white blood cell count (WBC) associate with body adiposity and other cardiometabolic risk factors, as well as accelerometer-measured sedentary behavior (SB) and physical activity (PA), when adjusted for body mass index (BMI).

METHODS

The cross-sectional analysis included 144 participants (42 men) with a mean age of 57.0 years and a mean BMI of 31.7 kg/m². SB and standing time, breaks in sedentary time and PA were measured during four consecutive weeks with hip-worn accelerometers. A fasting blood sample was collected from each participant during the 4-week measurement period and analyzed using Sysmex XN and Cobas 8000 c702 analyzers. Associations of WBC, Hb and other red blood cell markers with cardiometabolic risk factors and physical activity were examined by Pearson's partial correlation coefficient test and with linear mixed regression models.

RESULTS

In sex- and age-adjusted correlation analyses both BMI and waist circumference correlated positively with Hb, WBC, red blood cell count (RBC), and hematocrit. Hb was also positively correlated with systolic blood pressure, insulin resistance scores, liver enzymes, LDL, and triglyceride levels. Sedentary time correlated positively with WBC, whereas standing time correlated negatively with WBC. Lying time correlated positively with WBC, RBC, hematocrit, and Hb. Regarding SB and PA measures, only the association between lying time and RBC remained significant after adjustment for the BMI.

CONCLUSION

We conclude that body adiposity, rather than components of SB or PA, associates with Hb levels and WBC, which cluster with general metabolic derangement.

Effects of reducing sedentary behaviour duration by increasing physical activity, on cognitive function, brain function and structure across the lifespan: a systematic review protocol

INTRODUCTION

Greater engagement in sedentary behaviours has been related to poorer cognitive functions in epidemiological research. However, the effects of reducing sedentary behaviour duration on cognitive function, brain function, and structure remain poorly understood. This systematic review aims to synthesise the evidence on the effects of reducing sedentary behaviour duration by increasing time spent in physical activity on cognitive function, brain structure and function in apparently healthy children, adolescents and adults.

METHODS AND ANALYSIS

The protocol follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The literature search will be conducted (search dates: August-September 2022) across six databases: PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (via EBSCO Host), PsycINFO (via ProQuest), SPORTDiscus and Web of Science (Science and Social Science Citation Index). The inclusion criteria are as follows: randomised and non-randomised experimental studies as defined by the Cochrane Handbook, published in English, in peer-reviewed journals, and as theses or dissertations. References of included papers will be screened for additional studies. Acute and chronic interventions targeting children (≥ 4 years), adolescents, younger adults (≥ 18-40 years), middle-aged (40-64 years) and older adults (65+ years) will be eligible. Methodological quality will be assessed with the Effective Public Health Practice Project quality assessment tool for quantitative studies. Qualitative synthesis will be stratified by intervention type (acute vs chronic), intervention content (reducing sedentary time or interrupting prolonged sitting) and outcome (cognitive, brain structure and function).

ETHICS AND DISSEMINATION

No primary data collection will be conducted as part of this systematic review. Study findings will be disseminated through peer-reviewed publications, conference presentations and social media.

PROSPERO REGISTRATION NUMBER

CRD42020200998.

Total Sedentary Time and Cognitive Function in Middle-Aged and Older Adults: A Systematic Review and Meta-analysis

Background

An estimated 47 million people have dementia globally, and around 10 million new cases are diagnosed each year. Many lifestyle factors have been linked to cognitive impairment; one emerging modifiable lifestyle factor is sedentary time.

Objective

To conduct a systematic review and meta-analysis of peer-reviewed literature examining the association between total sedentary time with cognitive function in middle-aged and older adults under the moderating conditions of (a) type of sedentary time measurement; (b) the cognitive domain being assessed; (c) looking at sedentary time using categorical variables (i.e., high versus low sedentary time); and (d) the pattern of sedentary time accumulation (e.g., longer versus shorter bouts). We also aimed to examine the prevalence of sedentary time in healthy versus cognitively impaired populations and to explore how experimental studies reducing or breaking up sedentary time affect cognitive function. Lastly, we aimed to conduct a quantitative pooled analysis of all individual studies through meta-analysis procedures to derive conclusions about these relationships.

Methods

Eight electronic databases (EMBASE; Web of Science; PsycINFO; CINAHL; SciELO; SPORTDiscus; PubMed; and Scopus) were searched from inception to February 2021. Our search included terms related to the exposure (i.e., sedentary time), the population (i.e., middle-aged and older adults), and the outcome of interest (i.e., cognitive function). PICOS framework used middle-aged and older adults where there was an intervention or exposure of any sedentary time compared to any or no comparison, where cognitive function and/or cognitive impairment was measured, and all types of quantitative, empirical, observational data published in any year were included that were published in English. Risk of bias was assessed using QualSyst.

Results

Fifty-three studies including 83,137 participants met the inclusion criteria of which 23 studies had appropriate data for inclusion in the main meta-analysis. The overall meta-analysis suggested that total sedentary time has no association with cognitive function (r = −0.012 [95% CI − 0.035, 0.011], p = 0.296) with marked heterogeneity (I² = 89%). Subgroup analyses demonstrated a significant negative association for studies using a device to capture sedentary time r = −0.035 [95% CI − 0.063, − 0.008], p = 0.012). Specifically, the domains of global cognitive function (r = −0.061 [95% CI − 0.100, − 0.022], p = 0.002) and processing speed (r = −0.067, [95% CI − 0.103, − 0.030], p < 0.001). A significant positive association was found for studies using self-report (r = 0.037 [95% CI − 0.019, 0.054], p < 0.001). Specifically, the domain of processing speed showed a significant positive association (r = 0.057 [95% CI 0.045, 0.069], p < 0.001). For prevalence, populations diagnosed with cognitive impairment spent significantly more time sedentary compared to populations with no known cognitive impairments (standard difference in mean = −0.219 [95% CI − 0.310, − 0.128], p < 0.001).

Conclusions

The association of total sedentary time with cognitive function is weak and varies based on measurement of sedentary time and domain being assessed. Future research is needed to better categorize domains of sedentary behaviour with both a validated self-report and device-based measure in order to improve the strength of this relationship. PROSPERO registration number: CRD42018082384.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00507-x.

Potential Effects of Resistant Exercise on Cognitive and Muscle Functions Mediated by Myokines in Sarcopenic Obese Mice

Recently, it has been demonstrated that in sarcopenic obesity (SO), physical activity could improve cognitive functions. Moreover, previous studies suggested that muscle contraction could influence cognitive function via myokines. This study investigated the potential effects of resistant exercise on cognitive and muscle functions in SO. SO was induced by a high-fat diet treatment for 8 weeks in 8-month-old male C57BL/6J mice. Then, resistant exercise (ladder climbing) for 8 weeks was performed. Muscle and cognitive function tests and morphological analysis were conducted. The protein levels of myokines were investigated in muscle, plasma, and the hippocampus in sarcopenic obese mice. Muscle and cognitive functions were significantly elevated in the obesity-exercise group (EX) compared to the obesity-control group (OB). Interestingly, muscle function was positively correlated with cognitive function. Abnormal morphological changes in the hippocampus were ameliorated in EX compared to OB, but not in the muscle. Protein levels of cognitive function-related myokines and energy metabolism-related markers in EX were significantly elevated in both muscle and hippocampus compared to those in OB. Interestingly, the protein level of brain-derived neurotrophic factor (BDNF) in EX was simultaneously increased in all tissues including muscle, plasma, and hippocampus compared to that in OB. In conclusion, modulation of muscle-derived cognitive function-related myokines in various pathological conditions via a resistant exercise could be a possible way of relieving muscle and cognitive dysfunction.

Device-measured sedentary behaviour and anxiety symptoms during adolescence: a 6-year prospective cohort study

BACKGROUND

Sedentary behaviour is potentially a modifiable risk factor for anxiety disorders, a major source of global disability that typically starts during adolescence. This is the first prospective study of associations between repeated, device-based measures of sedentary behaviour and anxiety symptoms in adolescents.

METHODS

A UK cohort with 4257 adolescents aged 12 at baseline (56% female). Main exposures were sedentary behaviour and physical activity measured using accelerometers for 7-days at ages 12, 14, and 16. Primary outcome was anxiety symptom scores at age 18 from a Clinical Interview Schedule-Revised. We used adjusted negative binomial regression and iso-temporal substitution methods to analyse the data.

RESULTS

We found a positive association between sedentary behaviour at ages 12, 14, and 16, with anxiety symptoms at age 18, independent of total physical activity volume. Theoretically replacing an hour of daily sedentary behaviour for light activity at ages 12, 14, and 16, was associated with lower anxiety symptoms by age 18 by 15.9% (95% CI 8.7-22.4), 12.1% (95% CI 3.4-20.1), and 14.7% (95% CI 4-24.2), respectively. Whereas, theoretically replacing an hour of sedentary behaviour with moderate-to-vigorous physical activity was not associated with differences in anxiety symptoms. These results were robust to a series of sensitivity analyses.

CONCLUSION

Sedentary behaviour is a possible risk factor for increasing anxiety symptoms during adolescence, independent of total physical activity volume. Instead of focusing on moderate-to-vigorous activity, replacing daily sedentary behaviour with light activity during adolescence could be a more suitable method of reducing future anxiety symptoms.

Cognitive Benefits of Exercise: Is There a Time-of-Day Effect?

It is well established that physical activity benefits cognition. Further, the time of day one engages in physical activity has been suggested to influence cognition. Here, we aimed to understand if there is a time-of-day effect (morning or afternoon) of physical activity on cognition, i.e., if exercising in the morning or afternoon might bring greater cognitive benefits. A total of 56 participants were allocated to one of two groups with the same baseline cognitive performance as well as fitness level (International Physical Activity Questionnaire—IPAQ): 27 to the morning intervention (M) group; and 29 to the afternoon intervention (A) group. In both groups, the participants engaged in an intermittent recovery test (Yo-yo), 4 times a week for 12 weeks. All participants were assessed with the d2 Test of Attention and the Borg scale of perceived exertion pre- and post- acute and chronic intervention. After the first bout of exercise and after 12 weeks, we observed cognitive improvements both in the M and A groups. Surprisingly, we do not find differences between the time of day regarding cognitive benefits. Our results do not support the existence of a time-of-day effect for the attentional cognitive benefits of exercise.

Machine Learning for Prediction of Cognitive Health in Adults Using Sociodemographic, Neighbourhood Environmental, and Lifestyle Factors

The environment we live in, and our lifestyle within this environment, can shape our cognitive health. We investigated whether sociodemographic, neighbourhood environment, and lifestyle variables can be used to predict cognitive health status in adults. Cross-sectional data from the AusDiab3 study, an Australian cohort study of adults (34-97 years) (n = 4141) was used. Cognitive function was measured using processing speed and memory tests, which were categorized into distinct classes using latent profile analysis. Sociodemographic variables, measures of the built and natural environment estimated using geographic information system data, and physical activity and sedentary behaviours were used as predictors. Machine learning was performed using gradient boosting machine, support vector machine, artificial neural network, and linear models. Sociodemographic variables predicted processing speed (r2 = 0.43) and memory (r2 = 0.20) with good accuracy. Lifestyle factors also accurately predicted processing speed (r2 = 0.29) but weakly predicted memory (r2 = 0.10). Neighbourhood and built environment factors were weak predictors of cognitive function. Sociodemographic (AUC = 0.84) and lifestyle (AUC = 0.78) factors also accurately classified cognitive classes. Sociodemographic and lifestyle variables can predict cognitive function in adults. Machine learning tools are useful for population-level assessment of cognitive health status via readily available and easy-to-collect data.

Sedentary behaviour and brain health in middle-aged and older adults: a systematic review

Sedentary behaviour may increase the risk of dementia. Studying physiological effects of sedentary behaviour on cerebral health may provide new insights into the nature of this association. Accordingly, we reviewed if and how acute and habitual sedentary behaviour relate to brain health factors in middle-aged and older adults (≥45 years). Four databases were searched. Twenty-nine studies were included, with mainly cross-sectional designs. Nine studies examined neurotrophic factors and six studied functional brain measures, with the majority of these studies finding no associations with sedentary behaviour. The results from studies on sedentary behaviour and cerebrovascular measures were inconclusive. There was a tentative association between habitual sedentary behaviour and structural white matter health. An explanatory pathway for this effect might relate to the immediate vascular effects of sitting, such as elevation of blood pressure. Nevertheless, due to the foremost cross-sectional nature of the available evidence, reverse causality could also be a possible explanation. More prospective studies are needed to understand the potential of sedentary behaviour as a target for brain health.

Effects of physical exercise on cognitive function of breast cancer survivors receiving chemotherapy: A systematic review of randomized controlled trials

Background

Cognitive impairment has a great negative impact on quality of life for breast cancer survivors. Emerging evidence suggested that physical exercise can improve cognitive function in order adults with Alzheimer's disease. However, less is known about the effects of physical exercise on cognitive function for breast cancer survivors. The purpose of this meta-analysis was to evaluate the effect of physical exercise on cognitive function in breast cancer survivors.

Methods

EMBASE, the Cochrane Library, Web of Science and PubMed were searched from the establishment of the databases to June 2021. Randomized controlled trials were included. All analysis were conducted using the Revman 5.3.

Results

12 studies (936 participants) indicated that exercise improved self-reported cognitive function (MD 10.12, 95% CI [5.49,14.76], p < 0.0001), cognitive fatigue (MD -5.41, 95% CI [-10.31,-0.51], p = 0.03) and executive function (MD -13.63, 95% CI [-21.86,-5.39], p = 0.0001).

Conclusion

Physical exercise can improve cognitive function for breast cancer survivors, particularly in self-reported cognitive function, and executive function. Future studies need to explore the effect of exercise on cognitive function from the frequency and duration of exercise.

•

Physical exercise can improve cognitive function among breast cancer survivors.

•

Aerobic exercise and combined exercise intervention were more effective than other exercise.

•

Physical exercise can improve self-reported cognitive function, cognitive fatigue and executive function in breast cancer patients.

Acute effects of physical activity patterns on plasma cortisol and brain-derived neurotrophic factor in relation to corticospinal excitability

Brain-derived neurotrophic factor (BDNF) and cortisol are both capable of modulating synaptic plasticity, but it is unknown how physical activity-induced changes in their plasma levels relate to corticospinal plasticity in humans. Sixteen inactive middle-aged men and women participated in three separate interventions consisting of 3hours prolonged sitting (SIT); 3hours sitting interrupted every 30minutes with frequent short physical activity breaks (FPA); and 2.5hours prolonged sitting followed by 25minutes of moderate intensity exercise (EXE). These 3hour sessions were each followed by a 30min period of paired associative stimulation over the primary motor cortex (PAS). Blood samples were taken and corticospinal excitability measured at baseline, pre PAS, 5min and 30min post PAS. Here we report levels of plasma BDNF and cortisol over three activity conditions and relate these levels to previously published changes in corticospinal excitability of a non-activated thumb muscle. There was no interaction between time and condition in BDNF, but cortisol levels were significantly higher after EXE compared to after SIT and FPA. Higher cortisol levels at pre PAS predicted larger increases in corticospinal excitability from baseline to all subsequent time points in the FPA condition only, while levels of BDNF at pre PAS did not predict such changes in any of the conditions. Neither BDNF nor cortisol modified changes from pre PAS to the subsequent time points, suggesting that the increased corticospinal excitability was not mediated though an augmented effect of the PAS protocol. The relationship between cortisol and plasticity has been suggested to be U-shaped. This is possibly why the moderately high levels of cortisol seen in the FPA condition were positively associated with changes AURC, while the higher cortisol levels seen after EXE were not. A better understanding of the mechanisms for how feasible physical activity breaks affect neuroplasticity can inform the theoretical framework for how work environments and schedules should be designed. DATA AVAILABILITY: Data are available from the corresponding author upon reasonable request.

Effect of Physical Activity on Cognitive Impairment in Patients With Cerebrovascular Diseases: A Systematic Review and Meta-Analysis

Background and Purpose

This study investigates the effect of physical activity (PA) on cognition in patients with cerebrovascular disease and explored the maximum benefit of different PA characteristics.

Methods

Databases, such as Pubmed, Web of Science, Embase, and Cochrane Library, were searched from their inception to May 31, 2021. Standardized mean difference (SMD) and 95% confidence intervals (CIs) were calculated to generate a forest plot. In addition, subgroup analysis, moderation analysis, and regression analysis were performed to explore the possible adjustment factors.

Results

In total, 22 studies that met the criteria were included, demonstrating data from 1,601 participants. The results indicated that PA produced a positive effect on the global cognition for patients with cerebrovascular disease (SMD: 0.20 [95% CI: 0.12-0.27]), at the same time, PA training prominently improved executive function (SMD: 0.09 [95% CI: 0.00-0.17]) and working memory (SMD: 0.25 [95% CI: 0.10-0.40]). Furthermore, patients with baseline cognitive impairment received the greater benefit of PA on cognition (SMD: 0.24 [95% CI: 0.14-0.34]) than those without cognitive impairment before intervention (SMD: 0.15 [95% CI: 0.04-0.26]). For patients in the acute stage (≤ 3 months), PA did not rescue impairment dysfunction significantly (SMD: 0.08 [95% CI: -0.04-0.21]) and remarkable cognitive gains were detected in the chronic stage of participants (>3 months) (SMD: 0.25 [95% CI: 0.16-0.35]). Moderate intensity PA showed a larger pooled effect size (SMD: 0.23 [95% CI: 0.11-0.36]) than low intensity (SMD: -0.01 [95% CI: -0.44-0.43]) and high intensity (SMD: 0.16 [95% CI: 0.03-0.29]). However, the different types, duration, and frequency of PA resulted in no differences in the improvement of cognitive function. Further regression analysis demonstrated that the beneficial effects of PA on cognition are negatively correlated with age (p < 0.05).

Conclusions

This study revealed that PA can prominently improve the cognitive ability in patients with cerebrovascular diseases and strengthened the evidence that PA held promise as a widely accessible and effective non-drug therapy for vascular cognitive impairment (VCI).

Optimal dose and type of exercise to improve cognitive function in older adults: A systematic review and bayesian model-based network meta-analysis of RCTs

OBJECTIVE

To examine the dose-response relationship between overall and specific types of exercise with cognitive function in older adults.

DESIGN

Systematic Review and Bayesian Model-Based Network Meta-Analysis.

DATA SOURCES

Systematic search of MEDLINE, Web of Science, Scopus, PsycINFO and SPORTDiscus.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomized controlled trials of exercise interventions in participants aged 50 years or over, and that reported on at least one global cognition outcome.

RESULTS

The search returned 1998 records, of which 44 studies (4793 participants; 102 different effect sizes) were included in this review with meta-analysis. There was a non-linear, dose-response association between overall exercise and cognition. We found no minimal threshold for the beneficial effect of exercise on cognition. The estimated minimal exercise dose associated with clinically relevant changes in cognition was 724 METs-min per week, and doses beyond 1200 METs-min per week provided less clear benefits. We also found that the dose-response association was exercise type dependent, and our results show that clinically important effects may occur at lower doses for many types of exercise. Our findings also highlighted the superior effects of resistance exercises over other modalities.

CONCLUSIONS

If provided with the most potent modalities, older adults can get clinical meaningful benefits with lower doses than the WHO guidelines. Findings support the WHO recommendations to emphasise resistance training as a critical component of interventions for older adults.

A Novel Intensity-Based Approach to Increasing Prefrontal Cerebral Oxygenation by Walking Exercise

Regional cerebral blood flow (rCBF) increases after moderately intense exercise and is significantly correlated with cognitive function. However, no intensity-based physiological indicator for enhancing rCBF during low- to-moderate-intensity exercise has been proposed. The purpose of this study was to develop a physiological indicator housed in a wearable device to determine whether low-to-moderate intensity walking can increase rCBF. A cross-sectional study with four parallel arms was performed. Each of 114 participants was randomly assigned to either the moderate, low-to-moderate, low, or very low walking intensity groups. A novel dynamic cardiac force meter (CFM) was used to quantify walking intensity. Heart rate and hemoencephalography (HEG) were measured during each phase of the session. Compared to baseline, HEG significantly increased in both the submaximal exercise and recovery phases in members of the low-to-moderate intensity group but not the very low intensity group. Low-to-moderate intensity walking improves prefrontal cerebral blood oxygenation. The present results demonstrate the usefulness of a dynamic CFM housed in a wearable device for quantifying the intensity of walking exercise aimed at increasing prefrontal blood oxygenation. The results of the study may help guide further development of exercise strategies for brain disease patients and the ageing population.

Acute effect of breaking up prolonged sitting on cognition: a systematic review

OBJECTIVES

To review the current evidence on the acute effects of interrupting prolonged periods of sitting with intermittent physical activity (PA) on cognition in healthy populations.

DESIGN

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

METHODS

Studies were included if they investigated the acute effects of taking regular PA breaks from sitting on cognition in healthy populations without any cardiovascular disease, history of brain injury, or psychiatric or neurological disorder. Four electronic databases-PubMed, Scopus, MEDLINE and ProQuest-were searched for eligible studies on 20 September 2020. Study quality was assessed using the Physiotherapy Evidence Database scale.

RESULTS

Seven studies, involving 168 participants aged between 18 and 80 years, were eligible for inclusion in this review. Three of the seven studies found positive effects of interrupting sitting with either (a) 3 min of relatively high-intensity (6 km/hour) walking every 30 min on attention and inhibitory control in young adults; (b) hourly breaks with progressively longer duration (10-30 min) of very light-intensity cycling/walking on attention, working memory and cognitive flexibility in adults with obesity; or (c) an initial bout of continuous moderate-intensity exercise, followed by interruption of post-exercise sitting with 3 min breaks of light-intensity walking (3.2 km/hour) every 30 min, on working memory in older adults with overweight.

CONCLUSION

Given the limited evidence with mixed findings on this topic in the literature and the heterogeneity of PA protocols across the included studies, the results regarding the effectiveness of interrupting prolonged sitting with PA breaks in improving cognition warrant further verification.

PROSPERO REGISTRATION NUMBER

CRD42020147536.

Effect of forced treadmill exercise on stimulation of BDNF expression, depression symptoms, tactile memory and working memory in LPS-treated rats

Neuroinflammation has been implicated in cognitive dysfunction and the occurrence of depression in neurodegenerative diseases. Brain-derived neurotrophic factor (BDNF) is believed to be involved with the benefits of exercise training in boosting memory and learning processes and antidepressant therapies. This study aimed to investigate the effect of forced treadmill exercise on hippocampal BDNF expression levels, depression symptoms, tactile memory and working memory in lipopolysaccharide (LPS)-treated rats. For this purpose, 40 male Wistar rats received 0.25 mg/kg of LPS or saline intraperitoneally for 9 consecutive days before exercise. They again received a single injection of 0.5 mg/kg of LPS or saline on days 20 and 41 after exercise. Exercise groups had to run on a motorized treadmill 5 days a week for 8 weeks. Following the last exercise training session, forced swim test (FST), Y maze and novel object recognition (NOR) task were performed. Finally, the hippocampus of rats was removed and used for determination of BDNF expression levels by real-time polymerase chain reaction (real-time PCR). The data showed that LPS decreased BDNF expression levels, Y maze score, and recognition index in NOR and increased immobility time in FST (p < 0.05). In contrast, forced treadmill exercise increased BDNF expression levels and improved the percentage of spontaneous alternation, recognition index, and immobility time in LPS-treated rats (p < 0.05). There was a significant correlation between BDNF expression levels with immobility time and recognition index (p < 0.05) but not with the percentage of spontaneous alternation (p > 0.05). The findings suggest that forced treadmill exercise may protect the brain of LPS-treated rats by improving the symptoms of depression and cognitive function through its effect on BDNF expression levels.

ABBaH teens: Activity Breaks for Brain Health in adolescents: study protocol for a randomized crossover trial

Background

Physical activity breaks are widely being implemented in school settings as a solution to increase academic performance and reduce sitting time. However, the underlying physiological mechanisms suggested to improve cognitive function from physical activity and the frequency, intensity, and duration of the breaks remain unknown. This study will investigate the effects of frequent, short physical activity breaks during prolonged sitting on task-related prefrontal cerebral blood flow, cognitive performance, and psychological factors. Additionally, the moderating and mediating effects of arterial stiffness on changes in cerebral blood flow will be tested.

Methods

This is a protocol for a randomized crossover study that will recruit 16 adolescents (13–14 years old). Participants will undergo three different conditions in a randomized order, on three separate days, involving sitting 80 min with a different type of break every 17 min for 3 min. The breaks will consist of (1) seated social breaks, (2) simple resistance activities, and (3) step-up activities. Before and after the 80-min conditions, prefrontal cerebral blood flow changes will be measured using functional near-infrared spectroscopy (primary outcome), while performing working memory tasks (1-, 2-, and 3-back tests). Arterial stiffness (augmentation index and pulse wave velocity) and psychological factors will also be assessed pre and post the 80-min interventions.

Discussion

Publication of this protocol will help to increase rigor in science. The results will inform regarding the underlying mechanisms driving the association between physical activity breaks and cognitive performance. This information can be used for designing effective and feasible interventions to be implemented in schools.

Trial registration

www.ClinicalTrials.gov, NCT04552626. Retrospectively registered on September 21, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05972-5.

Co-Production at Work: The Process of Breaking Up Sitting Time to Improve Cardiovascular Health. A Pilot Study

Prolonged sitting negatively affects several cardiovascular disease biomarkers. Current workplace physical activity interventions to reduce sitting result in inconsistent uptake and adherence rates. Co-production attempts to improve the translation of evidence to practice through engaging the participants within the intervention design, improving the context sensitivity and acceptability of the intervention. A needs analysis questionnaire was initially conducted (n = 157) to scope workplace behaviours and attitudes. A development group (n = 11) was consulted in focus groups around the needs analysis findings and asked to comment on the feasibility of a proposed intervention. A pilot intervention was then carried out (n = 5). The needs analysis indicated that only 1.8% (n = 4) engaged in occupational physical activity, and 68.7% (n = 103) sat for ≥6 h during their working day. Through the focus groups, an intervention breaking up sitting time hourly with five-minute walking breaks was co-produced. Cultural and pragmatic issues concerning the implementation of frequent physical activity breaks from sitting and the subsequent impact on work productivity were highlighted. The pilot intervention increased the number of breaks from sedentary behaviour from 2 to 11. The co-production methodology resulted in a research- and stakeholder-guided compromise. Large-scale intervention implementation is required before firm effectiveness conclusions can be made.

From urban neighbourhood environments to cognitive health: a cross-sectional analysis of the role of physical activity and sedentary behaviours

BACKGROUND

There is a dearth of studies on the effects of the neighbourhood environment on adults' cognitive function. We examined how interrelated aspects of the built and natural neighbourhood environment, including air pollution, correlate with adults' cognitive function, and the roles of physical activity and sedentary behaviours in these associations.

METHODS

We used data from 4,141 adult urban dwellers who participated in the Australian Diabetes, Obesity and Lifestyle 3 study on socio-demographic characteristics, neighbourhood self-selection, physical activity and sedentary behaviours, and cognitive function. Neighbourhood environmental characteristics included population density, intersection density, non-commercial land use mix, and percentages of commercial land, parkland and blue space, all within 1 km residential buffers. We also calculated annual mean concentrations of NO2 and PM2.5. Generalised additive mixed models informed by directed acyclic graphs were used to estimate the total, direct and indirect effects of environmental attributes on cognitive functions and the joint-significance test was used to examine indirect effects via behaviours.

RESULTS

In the total effects models, population density and percentage of parkland were positively associated with cognitive function. A positive association of PM2.5 with memory was also observed. All neighbourhood environmental attributes were directly and/or indirectly related to cognitive functions via other environmental attributes and/or physical activity but not sedentary behaviours. Engagement in transportation walking and gardening frequency partially mediated the positive effects of the neighbourhood environment on cognitive function, while frequency of transportation walking mediated the negative effects.

CONCLUSIONS

In the context of a low-density country like Australia, denser urban environments with access to parkland may benefit residents' cognitive health by providing opportunities for participation in a diversity of activities. A more fine-grained characterisation of the neighbourhood environment may be necessary to tease out the negative and positive impacts of inter-related characteristics of urban neighbourhood environments on cognitive function.

Short-term effects of a social media-based intervention on the physical and mental health of remotely working young software professionals: A randomised controlled trial

The present study aimed to explore the short term effects of a social media-based intervention on the physical and mental health of the software professionals working remotely during the pandemic. Sixty software professionals with poor physical and mental health were randomised to Facebook-based intervention (FIIT) and a control (CONT) group for 2 months. Forty-six remote workers (26.25 ± 3.49 years) completed the study (FIIT = 22; CONT = 26). All the respondents had the median sitting time (7.07 ± 2.30 h/day) during office hours on workdays. We found a significant difference in the sitting time during office hours in workday within the subjects (F_1,46  = 4.66; p < .004; η_p ²  = .048) and between the subjects (F_1,46  = 3.81; p < .004; η_p ²  = .040). Post hoc analysis revealed participants in the FIIT group reduced their sitting time by 58 min during office hours during a typical workday compared with the control group. Nevertheless, we found a significant difference in the scores of stress, anxiety and depression within and between the groups. Short-term social media-based physical and mental health intervention may improve physical and mental health scores in the desk-based office workers working remotely.

Are acute sitting-induced changes in inflammation and cerebrovascular function related to impaired mood and cognition?

Purpose

Sedentary behaviour is negatively associated with mood and cognition, yet how acute sitting contributes to these overall associations is unknown. Since sitting heightens inflammation and impairs cerebrovascular function, this study investigated the hypothesis that these sitting-induced changes are related to impaired mood and cognition.

Methods

Twenty-five healthy desk workers (18 male, 28.3 ± 7.5 years, BMI: 24.2 ± 3.3 kg∙m^-2) were recruited. During laboratory visit one, participants were familiarised with cognitive performance tests measuring executive function, attention and working memory. During laboratory visit two, participants completed 6 h of continuous, uninterrupted sitting. At baseline and after 6 h, serum markers of inflammation, middle cerebral artery blood flow velocity (MCAv), cerebrovascular carbon dioxide reactivity (CVR), dynamic cerebral autoregulation (CA), cognitive performance and mood (positive and negative affect, alert, contented and calm) were assessed. Data were analysed using paired-samples t tests and correlation analyses.

Results

Following sitting, C-reactive protein (∆-1.0 µg/ml) and tissue plasminogen activator (∆-360.4 pg/ml) decreased (p < 0.05), MCAv reduced (∆-2.9 cm∙s^-1, p = 0.012) and normalised gain increased in the very low frequency range, indicating impaired CA (∆ + 0.22%·mmHg^-1, p = 0.016). Positive affect (∆-4.6, p < 0.001), and alert (∆-10.6 p = 0.002) and contented (∆-7.4, p = 0.006) mood states also decreased following sitting. No significant changes in interleukin-6, tumour necrosis factor-alpha, von Willebrand factor, CVR or cognitive performance were observed (p > 0.05). The observed changes in inflammation and cerebrovascular function were not related to changes in mood (p > 0.05).

Conclusion

Alterations in inflammation or cerebrovascular function following six hours of prolonged, uninterrupted sitting are not related to the observed reductions in mood, indicating other mechanisms underlie the relationship between acute sitting and mood disturbances.

Mutual stimulatory signaling between human myogenic cells and rat cerebellar neurons

Insight into the bidirectional signaling between primary human myogenic cells and neurons is lacking. For this purpose, human myogenic cells were derived from the semitendinosus and gracilis muscles of five healthy individuals and co-cultured with cerebellar granule neurons from two litters of 7-day-old Wistar rat pups, in muscle medium or neural medium, alongside monocultures of myogenic cells or neurons. RT-PCR was performed to determine human mRNA levels of GAPDH, Ki67, myogenin, and MUSK, and the acetylcholine receptor subtypes CHRNA1, CHRNB1, CHRNG, CHRND, and CHRNE, and rat mRNA levels of GAPDH, Fth1, Rack1, vimentin, Cdh13, and Ppp1r1a. Immunocytochemistry was used to evaluate neurite outgrowth (GAP43) in the presence and absence of myogenic cells. Co-culture with primary neurons lead to higher myogenic cell gene expression levels of GAPDH, myogenin, MUSK, CHRNA1, CHRNG, and CHRND, compared to myogenic cells cultured alone. It appeared that neurons preferentially attached to myotubes and that neurite outgrowth was enhanced when neurons were cultured with myogenic cells compared to monoculture. In neural medium, rat mRNA levels of GAPDH, vimentin, Cdh13, and Ppp1r1a were greater in co-culture, versus monoculture, whereas in muscle medium co-culture lead to lower levels of Fth1, Rack1, vimentin, and Cdh13 than monoculture. These findings demonstrate mutually beneficial stimulatory signaling between rat cerebellar granule neurons and human myogenic cells, providing support for an active role for both the neuron and the muscle cell in stimulating neurite growth and myogenesis. Bidirectional muscle nerve signaling.

Frequent, Short Physical Activity Breaks Reduce Prefrontal Cortex Activation but Preserve Working Memory in Middle-Aged Adults: ABBaH Study

Prolonged sitting is increasingly common and may possibly be unfavorable for cognitive function and mood. In this randomized crossover study, the effects of frequent, short physical activity breaks during prolonged sitting on cognitive task-related activation of the prefrontal cortex were investigated. The effects on working memory, psychological factors, and blood glucose were also examined, and whether arterial stiffness moderated prefrontal cortex activation. Thirteen subjects (mean age 50.5 years; eight men) underwent three 3-h sitting conditions, interrupted every 30-min by a different 3-min break on separate, randomized-ordered days: seated social interactions (SOCIAL), walking (WALK), or simple resistance activities (SRA). Arterial stiffness was assessed at baseline. Before and after each 3-h condition, psychological factors (stress, mood, sleepiness, and alertness) were assessed through questionnaires and functional near-infrared spectroscopy (fNIRS) was used to measure changes in prefrontal oxygenated hemoglobin (Oxy-Hb), indicative of cortical activation, while performing working memory tasks [1- (baseline), 2-, and 3-back]. Blood glucose levels were continuously measured throughout the conditions. Results revealed no significant changes in Oxy-Hb during the 2-back compared with the 1-back test in any condition, and no time-by-condition interactions. During the 3-back test, there was a significant decrease in Oxy-Hb compared with the 1-back after the WALK condition in the right prefrontal cortex, but there were no time-by-condition interactions, although 3-back reaction time improved only in the WALK condition. Mood and alertness improved after the WALK condition, which was significantly different from the SOCIAL condition. Arterial stiffness moderated the effects, such that changes in Oxy-Hb were significantly different between WALK and SOCIAL conditions only among those with low arterial stiffness. Blood glucose during the interventions did not differ between conditions. Thus, breaking up prolonged sitting with frequent, short physical activity breaks may reduce right prefrontal cortex activation, with improvements in some aspects of working memory, mood, and alertness. Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT04137211.

Physical exercise consequences on memory in obesity: A systematic review

Obesity is associated with changes in memory. Thus, the aim of this systematic review was to investigate the physical exercise consequences on memory in obesity. A search was carried out in the PubMed, Lilacs, and Scielo databases with the following descriptors: "physical exercise," "memory," and "obesity." A total of 16 studies were analyzed in this review. Low, moderate, and high intensity exercise training showed positive effects on memory in patients with obesity (100%). The animal models of obesity used in their physical exercise protocols: treadmill (72.7%) or wheel running (27.3%). Most of the animal studies (81.8%) revealed positive effects of the physical exercise protocol on memory in obesity. Mouse was the most commonly used animal (54.5%), and a 60% high-fat diet (HFD) was the most commonly method used to induce obesity (82%). We did not identify any knockout model of obesity that was used to evaluate memory and used physical exercise as the main intervention. Thus, exercise training, independently if it is resistance or endurance training, seems to be an excellent intervention to prevent and inhibit cognitive impairment and memory loss on obese patients and animal models of obesity.

Effects of Acute Exercise on Memory Performance in Middle-Aged and Older Adults

Numerous studies show that exercise benefits memory and some show that acute exercise prior to encoding has larger benefits than exercise after encoding. This study was designed to investigate the effects of acute exercise on memory in middle-aged and older adults (Mage = 64.71 years) and to explore the influence of the timing of the exercise on these effects. Using a within-subjects design, moderate-intensity exercise (20 min) was either not performed (control), performed before the task (exercise prior), or performed after the task (exercise post). Memory was assessed using the Rey Auditory Learning Verbal Test. For short- and long-term memory and learning, significantly more words were remembered in the exercise-prior condition than the others. For 24-hr recall, participants remembered significantly more words in the exercise-prior condition than exercise post, which was better than control. Exercise benefits memory for healthy middle-aged and older adults, with the greatest benefits when performed prior to encoding.

Swimming exercise improves short- and long-term memories: Time-course changes

The beneficial effects of exercise training on memory formation are well documented. However, the memory enhancement profile following the time-course of exercise training remains unknown. In this investigation, changes in the spatial hippocampal memory following a time-course of swimming exercise training were examined. Young adult Wistar rats were tested for both short-term and long-term memories using the radial arm water maize (RAWM) paradigm following 0, 1, 7, 14, and 28 days of swimming exercise training (60 min per day, 5 days/week)s. The mean total errors on RAWM during the learning phase and memory testing remained the same (p > 0.5) after 1 day of swimming exercise. On the other hand, swimming exercise-induced significant enhancement to the learning phase and memory formation after 7 days of training (p < 0.01). Errors decreased (p < 0.0001) after 7 days of training and remained lower (p < 0.0001) than baseline without differences between 7, 14, and 28 days (p > 0.5). Similarly, short- and long-term memories improved after 7 days (p < 0.05) of training as compared to the baseline without differences between 7, 14, and 28 days (p > 0.05). The time course of improvement of learning and both short- and long-term memories after swimming exercise were evident after 7 days and plateaued thereafter. Results of the current study could form the base for future utilization of exercises to enhance cognitive function in healthy individuals.

Does breaking up prolonged sitting improve cognitive functions in sedentary adults? A mapping review and hypothesis formulation on the potential physiological mechanisms

Background

Prolonged (excessive) sitting is detrimentally associated with cardiovascular, metabolic and mental health. Moreover, prolonged sitting has been associated with poor executive function, memory, attention and visuospatial skills, which are important cognitive aspects of work performance. Breaking up prolonged sitting with standing or light-intensity exercises at the workplace is recognized as a potential measure in improving cognition. However, preliminary evidence, primarily from acute laboratory experiments, has enabled formulating hypothesis on the possible mechanistic pathways. Hence, the aim of this mapping review is to gather preliminary evidence and substantiate possible physiological mechanisms underpinning the putative effects of breaking prolonged sitting on improving cognitive function among sedentary office workers.

Mapping method

We searched four databases to identify relevant studies that explored the effects of uninterrupted sitting on cognitive function. First, we introduce how prolonged sitting increases the risks of hyperglycemia, autonomic stability, inflammation, adverse hormonal changes and restrictions in cerebral blood flow (CBF) and alters cognitive function. Second, we elucidate the direct and indirect effects of breaking up prolonged sitting time that may prevent a decline in cognitive performance by influencing glycaemic variability, autonomic stability, hormones (brain derived neurotrophic factor, dopamine, serotonin), vascular functions, and CBF. We highlight the importance of breaking up prolonged sitting on metabolic, vascular and endocrine functions, which in turn may improve cognitive functions and eventually foster work productivity. Improved synaptic transmission or neuroplasticity due to increased brain glucose and mitochondrial metabolism, increased endothelial shear and CBF, increased brain neurotrophic factors (dopamine) and accelerated anti-inflammatory functions are some of the hypothetical mechanisms underpinning improved cognitive functions.

Conclusion

We postulate that improving cognitive function by breaking up prolonged sitting periods is biologically plausible with the myriad of (suggested) physiological mechanisms. Future experimental studies to ascertain the aforementioned hypothetical mechanisms and clinical trials to break sedentary behavior and improve cognitive functions in sedentary office workers are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04136-5.

Associations between activity fragmentation and subjective memory complaints in middle-aged and older adults

INTRODUCTION

Subjective memory complaints (SMC) are often considered a clinical marker of mild cognitive impairment and dementia and could manifest as shortening of activity bouts throughout the day causing daily activity to accumulate in a more fragmented pattern. In the current study we explored the association between activity fragmentation and SMC in middle-aged and older adults.

METHODS

We used data from 3820 participants in the National Health and Nutrition Examination Survey (2003-2006) with valid accelerometer SMC data. The analyses were conducted in 2020. To calculate activity fragmentation, an active-to-sedentary transition probability was calculated as the number of physical activity bouts (i.e., consecutive minutes registering 100+ counts/min) divided by the total sum of minutes spent in physical activity. A multivariable ordinal logistic regression model was conducted to examine the association between activity fragmentation (scaled) and SMC (yes/no).

RESULTS

Higher activity fragmentation was associated with an increased likelihood of self-reported SMC in the study population (Odd Ratio [95% Confidence Interval] = 1.335 [1.067, 1.669]; Average Marginal Effect [95%CI] = 0.029 [0.006, 0.052]; p-value = 0.021). This association was independent of total physical activity volume.

CONCLUSIONS

The findings provide support that studying fragmented activity patterns can be useful in identifying those at risk for SMC, over and above total volume of physical activity. Future longitudinal studies are required to establish causality and the temporal order of the observed association. Nevertheless, activity fragmentation in middle-aged and older adults may reflect pre-clinical signs of future neurodegenerative processes indicating potential targets for modification through intervention.

Sedentary patterns are associated with BDNF in patients with type 2 diabetes mellitus

PURPOSE

Exercise is beneficial to type-2 diabetes-mellitus (T2DM), and there is evidence showing that one of those benefits include a higher expression of brain-derived neurotrophic factor (BDNF), which has been implicated in improving fat oxidation and cognitive development. The deleterious effect of prolonged sedentary time (ST) on BDNF levels has never been examined in patients with T2DM. Our goal was to analyse the associations for sedentary patterns [i.e. breaks in ST per sedentary hour (BST-ST) and bouts of sedentary time (BSB) of different length] with BDNF in patients with T2DM, independent of moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF).

METHODS

Sample included 80 patients (38 women) with T2DM (58.3 ± 7.8 years). ST and MVPA were assessed by accelerometry (ActiGraph, GT3X + model), BDNF by blood collection and plasma quantification using commercial enzyme-linked immunosorbent assay kits, and CRF was determined using a Bruce protocol to exhaustion, on a motorized treadmill.

RESULTS

Positive associations for BST-ST (β = 0.155; p = 0.007) with BDNF, and negative associations for BSB longer than 15 min with BDNF were found (β = - 0.118; p = 0.049). Neither MVPA nor cardiorespiratory fitness eliminated the associations for BST-ST with BDNF, but MVPA eradicated the associations between BSB > 15 min and BDNF.

CONCLUSIONS

Our findings suggest that interrupting ST and especially avoiding longer sedentary periods (> 15 min) may be beneficial for BDNF plasma abundance that may influence metabolic and cognitive functioning of patients with T2DM, especially for the ones presenting lower MVPA levels.

TRIAL REGISTRATION

May 5, 2017, ClinicalTrials.govID:NCT03144505.

ABBaH: Activity Breaks for Brain Health. A Protocol for a Randomized Crossover Trial

Introduction: Extended periods of sitting may have detrimental effects on brain health. However, the effects of breaking up prolonged sedentary periods with frequent, short physical activity bouts on mechanisms to improve brain health remain unclear. Therefore, this study aims to investigate the immediate effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive function in the prefrontal cortex in middle-aged adults.

Methods: This is a protocol article to describe a randomized crossover study. We will collect data from 13 healthy adults, aged between 40 and 60 years old, with a body mass index <35 kg/m². Participants will be required to come into the laboratory on three occasions, sit for 3 h, and perform a different type of break for 3 min every 30 min at each visit in a random order, being either: (1) a social break; (2) brisk walk on a treadmill; or (3) simple resistance activities. Before and after each experimental condition, cerebral blood flow (primary outcome) will be measured using functional near-infrared spectroscopy (fNIRS), with short-separation channels, and working memory (1-, 2-, and 3-back on the computer) will be assessed. The following additional secondary outcomes will be collected: psychological factors (questionnaires); arterial stiffness; salivary cortisol levels; and blood glucose levels.

Conclusion: The results from this randomized crossover study will determine the effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive performance. Publication of this study protocol emphasizes the importance of registration and publication of protocols in the field of sedentary behavior research.

Feasibility and behavioral effects of prolonged static and dynamic standing as compared to sitting in older adults with type 2 diabetes mellitus

Background

Physical inactivity is prevalent in older adults with type 2 diabetes mellitus (T2DM) and may exacerbate their clinical symptoms. The aim of this study was to examine the feasibility of 4-h regular versus more dynamic standing sessions while performing routine desktop activities as a non-exercise physical activity intervention in older adults with T2DM to increase non-exercise activity.

Methods

Twelve older adult patients with T2DM (3 female; age 71 ± 4 years; Body mass index 34 ± 5 kg/m²) completed three sessions (baseline sitting followed by “static” or “dynamic” desktop standing sessions). Participants stood behind a regular height-adjustable desk in the “static” standing session. An upright dynamic standing desk, which provides cues to make small weight-shifting movements, was used for the “dynamic” standing session. Oxygen consumption, cognitive performance, as well as net standing duration, total movement activity, and musculoskeletal discomfort were assessed during all three sessions.

Results

All participants were able to complete all sessions. Oxygen consumption and overall movements progressively increased from sitting to static and dynamic standing, respectively (p < 0.001). The duration of breaks during standing (p = 0.024) and rate of total musculoskeletal discomfort development (p = 0.043) were lower in the dynamic standing compared to static standing sessions. There was no evidence of executive cognitive worsening during either standing session compared to sitting.

Conclusions

Prolonged 4-h standing as a simple non-exercise physical intervention is feasible in older adults with T2DM and may have metabolic (oxygen consumption) benefits. Increasing movement during desktop standing may offer incremental benefits compared to regular standing. Prolonged desktop standing might provide an effective intervention in T2DM older participants to target sedentariness.

Trial registration

ClinicalTrials.gov (NCT04410055), retrospectively registered May 27, 2020.

Associations of interruptions to leisure-time sedentary behaviour with symptoms of depression and anxiety

Interruptions to time spent sitting can ameliorate detrimental metabolic-health consequences of high volumes of sedentary time, but their potential mental health benefits have not been examined. We used the Swedish Health Profile Assessment database, a general health assessment offered to all employees working for companies or organisations connected to occupational and health services. Cross-sectional analyses examined data from 40,550 employees (60% male, mean age = 42 years), collected in 2017-2019. Participants reported the proportion of time (almost always; 75% of the time; 50% of the time; 25% of the time; and almost never) usually spent in leisure-time sedentary behaviours; and, separately, the frequency (never; rarely; sometimes; often; and very often) of interruptions (every 30 min) to sedentary time. Logistic regression models assessed associations of sedentary time, and the frequency of interruptions to sedentary time, with depression/anxiety symptoms. Fully adjusted models included physical exercise. Compared to those in the lowest sedentary time category, those in the medium and high categories had 1.52 (95% confidence interval (CI) = 1.40-1.66) and 3.11 (95% CI = 2.82-3.42) higher odds of frequent depression/anxiety symptoms, respectively. Compared to those who never/rarely interrupted their sedentary time, those who reported interruptions sometimes, often and very often had 0.72 (95% CI = 0.65-0.80), 0.59 (95% CI = 0.53-0.65), and 0.53 (95% CI = 0.46-0.59) lower odds of depression/anxiety symptoms, respectively. In stratified analyses, more frequent interruptions to sedentary time were associated with lower odds of depression/anxiety symptoms, except among those in the lowest interruptions categories (never/25% of the time). More regularly interrupting sitting during leisure-time may reduce the odds of experiencing symptoms of depression and anxiety.

Relationships between Physical Activity, Sedentary Behaviour and Cognitive Functions in Office Workers

Increasing evidence from animal experiments suggests that physical activity (PA) promotes neuroplasticity and learning. For humans, most research on the relationship between PA, sedentary behaviour (SB), and cognitive function has relied on self-reported measures of behaviour. Office work is characterised by high durations of SB combined with high work demands. While previous studies have shown that fitter office workers outperform their less fit colleagues in cognitive tests, the importance of PA and SB remains unknown. This study investigated associations between objectively measured PA and SB, using hip-worn accelerometers, and cognitive functions in 334 office workers. Time spent in moderate-to-vigorous PA (MVPA) was not associated with any cognitive outcome. However, time spent in SB tended to be positively associated with words recalled in free recall (β = 0.125). For the least fit participants, the average length of MVPA bouts was favourably related to Stroop performance (β = -0.211), while for the fitter individuals, a longer average length of MVPA bouts was related to worse recognition (β = -0.216). While our findings indicate that the length of MVPA bouts was associated with better Stroop performance in the least fit participants, our findings do not support the notion that more time spent in MVPA or less time in SB is associated with better cognitive function.