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

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.

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.

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.

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.