Accumulating evidence suggests that exercise training is associated with improvements in brain health in older adults, yet the extant literature is insufficient in detailing why exercise training facilitates brain structure and function. Specifically, few studies have employed the FITT-VP principle (i.e., Frequency, Intensity, Time, Type, Volume, and Progression) to characterize the exercise exposure, thus research is yet to specify which characteristics of exercise training benefit brain outcomes. To determine whether exercise training is consequential to cognitive and brain outcomes, we conducted a systematic review investigating the effects of exercise training on brain structure and function in older adults. PubMed and Scopus were searched from inception to February 2020, and study quality was assessed using the Cochrane risk-of-bias tool. A total of 24 randomized controlled trials were included. This systematic review indicates that older adults involved in exercise training may derive general benefits to brain health, as reflected by intervention-induced changes in brain structure and function. However, such benefits are dependent upon the dose of the exercise intervention. Importantly, current evidence remains limited for applied exercise prescriptions (e.g., volume, progression) and future research is needed to clarify the effects of exercise training on cognitive and brain outcomes in older adults.

Acute high-intensity interval training (HIIT) is a time-efficient strategy to improve physical health; however, the effect of acute HIIT on executive function (EF) is unclear. The aim of this study was to systematically review the existing evidence and quantify the effect of acute HIIT on overall EF and the factors affecting the relationship between acute HIIT and EF. Standard databases (i.e., the PubMed, Medline, Scopus, and CENTRAL databases) were searched for studies that examined the effect of acute HIIT on EF and were published up until January 2021. The overall EF and factors grouped by three categories, namely, EF assessment characteristics, exercise intervention characteristics, and sample and study characteristics, were analyzed by percentage of comparison for positive or null/negative effects. Overall, 35 of 57 outcomes (61%) across 24 studies revealed that acute HIIT has a positive effect on overall EF. In terms of factors, the results indicated that among EF assessment characteristics, groups, inhibition, updating, and the assessment occurring within 30 min may moderate the effect of acute HIIT on EF, while among exercise intervention characteristics, total time within 11 to 30 min may moderate the effect. Finally, among sample characteristics, age under 40 years may moderate the effect. Acute HIIT is generally considered a viable alternative for eliciting EF gains, with factors related to EF components, timing of the assessment, exercise total time, and age potentially moderating the effect of HIIT on EF.

Major Depressive Disorder (MDD) is a highly prevalent psychiatric disorder that impairs the cognitive function of individuals. Aerobic exercise stands out as a promising non-pharmacological intervention for enhancing cognitive function and promoting brain health. While positive impacts of aerobic exercise on executive function in adults with depression have been documented, a comprehensive understanding of its benefits on overall cognitive function, including memory, attention, and processing speed, along with key moderating factors in adults with MDD, remains unexplored. The purpose of the systematic review and meta-analysis was to investigate the effects of aerobic exercise on overall cognitive function in adults with MDD, and to explore whether cognitive sub-domains, aerobic exercise characteristics, and study and sample variables modify the effects of aerobic exercise on cognition. Six English electronic databases (Embase, Cochrane Central, Scopus, APA PsycInfo, PubMed, Web of Science) were searched from inception to 2 April 2023. Randomized trials, including adults aged 18 years or above with a diagnosis of clinical depression, of the effects of aerobic exercise on cognitive function in adults with MDD compared to non-aerobic exercise groups were included. A three-level meta-analysis was conducted utilizing a random-effects model in R. The quality of the studies was evaluated using the Physiotherapy Evidence Database (PEDro) scale. The PROSPERO registration number is CRD42022367350. Twelve randomized trials including 945 adults with MDD were included. Results indicated that aerobic exercise significantly improved overall cognitive function (g = 0.21; 95 % confidence intervals [CI] = 0.07, 0.34), and the sub-domains of memory (g = 0.25; 95 % CI = 0.06, 0.44) and executive function (g = 0.12; 95 % CI = 0.04, 0.20). Significant benefits in cognitive function were found from moderate-to-vigorous (mixed) intensity (g = 0.19; 95 % CI = 0.02, 0.37), aerobic exercise conducted 3 times per week (g = 0.23; 95 % CI = 0.10, 0.38), in sessions < 45 min (g = 0.59; 95 % CI = 0.28, 0.90), and 45–60 min (g = 0.16; 95 % CI = 0.07, 0.26), in aerobic exercise intervention ≤ 12 weeks (g = 0. 26; 95 % CI = 0.08, 0.44). This review only included peer-reviewed English-language studies, which may lead to a language bias. The results of the Egger's test suggested a potential publication bias. Aerobic exercise is efficacious in improving overall cognitive function and the sub-domains of memory and executive function in adults with major depressive disorder.

This study aimed to determine the dose-response relationship between exercise duration and task switching in older adults. Acute moderate intensity aerobic exercise for 20 min resulted in shorter response times than control and 10-min sessions in the heterogeneous, non-switch, and switch conditions, but not in the homogeneous condition. Additionally, linear and cubic trends between exercise duration and global switching performance as well as local switching performance were revealed with faster times being predicted by longer duration exercise; however, the cubic relationship resulted in performance following the 45-min session being not significantly different from the other three sessions. Acute aerobic moderate intensity exercise for 20 min is an effective duration to improve task switching. Although a longer duration of exercise is not optimal for benefiting task switching, it does not harm task switching in older adults and hence may be of value for other health-related reasons.

Background: The interplay between physical activity (PA) and sedentary behavior (SB) significantly influences cognitive health in older adults, with executive functions (EFs) being particularly vulnerable to lifestyle factors. However, previous research on older adults focused mainly on PA and is limited due to the lack of comprehensive consideration of other factors that influence EFs. Current guidelines suggest an association between sedentary behavior (SB) and EFs, yet few studies have examined the combined effects of PA and SB on EFs. Objective: This cross-sectional study aimed to explore the relationship between PA, SB, and EFs in older adults. Methods: A total of 116 healthy older adults aged ≥ 65 years were recruited and categorized into four groups based on activity lifestyles: higher PA and higher SB (PHSH); higher PA and lower SB (PHSL); lower PA and higher SB (PLSH); and lower PA and lower SB (PLSL). EFs were assessed using the Tower of London (TOL) task and the Stroop test, which measure high-order EFs (planning and problem-solving) and core EFs (inhibitory control), respectively. Results: The PHSL group performed better on the TOL task, with lower total move scores and shorter total problem-solving times, compared to the PLSH group. The total move score of the PLSL group was better, and the total problem-solving time of the PHSH group was shorter than those of the PLSH group. However, the Stroop test scores did not differ between the four groups. Conclusion: These findings suggest that increasing PA or reducing SB selectively enhances executive functions, particularly in planning and problem-solving, while less impacting inhibitory control in older adults. This highlights the importance of considering the nuanced effects of PA and SB on different aspects of executing functioning in older adults.