The Association of Cardiorespiratory Fitness on Memory Function: Systematic Review

The impact of acute bike desk usage before encoding and during early consolidation on memory task performance in university students and use case evaluation in an educational setting

This study examined the impact of using bike desks on cognitive function and memory among university students. Physical activity during adolescence offers enduring health benefits, yet sedentary behaviors prevail among young adults, posing significant health risks. Bike desks, integrating stationary cycling with ergonomic desk designs, aim to mitigate sedentary behavior while enhancing cognitive performance. Research indicates that acute aerobic exercise improves executive functions, memory, and attention, which is particularly beneficial in educational settings. The study employed the verbal paired associates learning task (VPAT) to assess memory performance when either bike desk usage at moderate intensity (intervention) or rest (control condition) occurred before encoding and during early consolidation in 26 young adult medicine and nursing students in a library setting. We hypothesised that bike desk usage will enhance memory encoding and consolidation compared to the control condition of rest. The results of our study showed no significant differences in VPAT scores or response latency between seated and bike desk conditions. Supplementary analysis, including a multiple linear regression model (R2: 0.773, Adjusted R2: 0.651, p <  0.001) revealed that higher BMI, more frequent bicycle or stationary bike usage, and higher physical activity category were associated with improved VPAT performance with the bike desk, while higher vigorous MET minutes per week negatively impacted performance. This analysis suggests there are potentially numerous uncharacterized modulators of the impact of exercise on memory, warranting further research to identify and understand these factors.

Cardiorespiratory fitness, hippocampal subfield morphology, and episodic memory in older adults

Objective

Age-related hippocampal atrophy is associated with memory loss in older adults, and certain hippocampal subfields are more vulnerable to age-related atrophy than others. Cardiorespiratory fitness (CRF) may be an important protective factor for preserving hippocampal volume, but little is known about how CRF relates to the volume of specific hippocampal subfields, and whether associations between CRF and hippocampal subfield volumes are related to episodic memory performance. To address these gaps, the current study evaluates the associations among baseline CRF, hippocampal subfield volumes, and episodic memory performance in cognitively unimpaired older adults from the Investigating Gains in Neurocognition Trial of Exercise (IGNITE) (NCT02875301).

Methods

Participants (N = 601, ages 65-80, 72% female) completed assessments including a graded exercise test measuring peak oxygen comsumption (VO2peak) to assess CRF, cognitive testing, and high-resolution magnetic resonance imaging of the hippocampus processed with Automated Segmentation of Hippocampal Subfields (ASHS). Separate linear regression models examined whether CRF was associated with hippocampal subfield volumes and whether those assocations were moderated by age or sex. Mediation models examined whether hippocampal volumes statistically mediated the relationship between CRF and episodic memory performance. Covariates included age, sex, years of education, body mass index, estimated intracranial volume, and study site.

Results

Higher CRF was significantly associated with greater total left (B = 5.82, p = 0.039) and total right (B = 7.64, p = 0.006) hippocampal volume, as well as greater left CA2 (B = 0.14, p = 0.022) and dentate gyrus (DG; B = 2.34, p = 0.031) volume, and greater right CA1 (B = 3.99, p = 0.011), CA2 (B = 0.15, p = 0.002), and subiculum (B = 1.56, p = 0.004) volume. Sex significantly moderated left DG volume (B = -4.26, p = 0.017), such that the association was positive and significant only for males. Total left hippocampal volume [indirect effect = 0.002, 95% CI (0.0002, 0.00), p = 0.027] and right subiculum volume [indirect effect = 0.002, 95% CI (0.0007, 0.01), p = 0.006] statistically mediated the relationship between CRF and episodic memory performance.

Discussion

While higher CRF was significantly associated with greater total hippocampal volume, CRF was not associated with all underlying subfield volumes. Our results further demonstrate the relevance of the associations between CRF and hippocampal volume for episodic memory performance. Finally, our results suggest that the regionally-specific effects of aging and Alzheimer's disease on hippocampal subfields could be mitigated by maintaining higher CRF in older adulthood.

Cardiorespiratory fitness and working memory in persons with traumatic brain injury: a cross-sectional analysis

INTRODUCTION

Cognitive impairment is a highly impactful consequence of traumatic brain injury (TBI) and there are limited evidence-based treatment practices to combat these impairments. Evidence from other populations suggest that aerobic exercise training (AET) is beneficial for a variety of cognitive deficits, but the research in persons with TBI to date is equivocal. One potential reason is the heterogeneity of exercise prescriptions and outcome measures. This stems from the fact that studies have not been designed based on previous data supporting a specific AET prescription to target a cognitive domain. The primary purpose of this cross-sectional analysis was to examine the relationship between cardiorespiratory fitness (CRF), as a cross-sectional surrogate of AET, and cognition in persons with TBI to inform future research.

METHODS

Cross-sectional analysis was conducted on baseline data of persons with TBI who completed neuropsychological assessments to evaluate several cognitive domains and a cardiopulmonary exercise test (CPET) to measure CRF. Based on the normal distribution of an outcome, Pearson's r or Spearman's ρ was calculated to measure the relationship between CRF and cognition.

RESULTS

Data were analyzed for all participants who demonstrated valid CPETs (n = 21 of 29). Based on the cycle ergometer-based norms of CRF, males in this sample were in the 69th percentile and females in this sample were in the 56th percentile, with high variability across individuals. Higher CRF, as measured by peak power output (Wpeak), was significantly associated with greater working memory (ρ = 0.465, p = 0.017), even after post-hoc corrections.

CONCLUSIONS

These data suggest average and highly variable CRF in persons with TBI of all severity and support cycle ergometry-based CPET testing in this population. Further, these data provide support for future research applying AET to target working memory and possibly other executive functions in persons with TBI. This research is a small step toward large-scale randomized controlled trials that can directly impact clinical care to treat cognitive symptoms post-TBI.

Associations Between Object Control Skills and Cognitive Functions in Boys, Younger and Older Men: Across-Sectional Study

Purpose: This study aimed to explore the association of cognitive function and process- as well product-oriented outcomes of object control skills (OCS) in boys, younger and older men. Methods: A total of 77 male participants took part in this study, including 35 primary school children (9.04 ± 0.53 years), 22 younger adults (23.5 ± 2.34 years), and 20 older adults (69.5 ± 4.43 years). We assessed the process-oriented performance of throwing, kicking, and catching performance using the component approach. For the product-oriented performance, throwing and kicking velocity was recorded with a STALKER SOLO 2.0 radar gun. For catching, the number of caught balls was assessed. Cognitive function was evaluated using the Trail-Making-Test (TMT) one day later. Results: Younger adults performed better in both domains than the other two groups. The results of the children and older adults were comparable in the motor and cognitive domains. However, the older adults yielded significantly better results for the process-oriented catching and product-oriented throwing performances. Moderate to strong correlations exist between OCS- and TMT performance, with significant correlations predominantly between product-oriented OCS results and TMT in children. Conclusion: The results of both domains support a hypothetical lifespan developmental trajectory with a progression from childhood to younger adult age and a degression in older adults. Furthermore, our results suggest that the suspected relationship between motor and cognitive function depends on age, the analyzed cognitive and motor skills, and the applied methodological approach (process-oriented vs. product-oriented).

Differentiating the influence of sedentary behavior and physical activity on brain health in late adulthood

Public health messaging calls for individuals to be more physically active and less sedentary, yet these lifestyle behaviors have been historically studied independently. Both physical activity (PA) and sedentary behavior (SB) are linked through time-use in a 24-hour day and are related to health outcomes, such as neurocognition. While the benefits of PA on brain health in late adulthood have been well-documented, the influence of SB remains to be understood. The purpose of this paper was to critically review the evolving work on SB and brain health in late adulthood and emphasize key areas of consideration to inform potential research. Overall, the existing literature studying the impact of SB on the components and mechanisms of brain health are mixed and inconclusive, provided largely by cross-sectional and observational work employing a variety of measurement techniques of SB and brain health outcomes. Further, many studies did not conceptually or statistically account for the role of PA in the proposed relationships. Therefore, our understanding of the way in which SB may influence neurocognition in late adulthood is limited. Future efforts should include more prospective longitudinal and randomized clinical trials with intentional methodological approaches to better understand the relationships between SB and the brain in late adulthood, and how these potential links are differentiated from PA.

Insulin Homeostasis Mediates the Relationship Between Cardiorespiratory Fitness and Cognitive Speed in Aging Adults

BACKGROUND

Cardiorespiratory fitness (CRF) supports cognition, though it is unclear what mechanisms underly this relationship. Insulin resistance adversely affects cognition but can be reduced with habitual exercise.

OBJECTIVE

We investigated whether insulin resistance statistically mediates the relationship between CRF and cognition.

METHODS

In our observational study, we included n = 1,131 cognitively unimpaired, nondiabetic older adults from a cohort characterized by elevated Alzheimer's disease (AD) risk. We estimated CRF (eCRF) using a validated equation that takes age, sex, body mass index, resting heart rate, and habitual physical activity as inputs. The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) quantified insulin resistance. Standardized cognitive factor scores for cognitive speed/flexibility, working memory, verbal learning/memory, and immediate memory were calculated from a battery of neuropsychological tests. Linear regression models and bootstrapped estimates of indirect effects were used to determine whether HOMA-IR mediated significant relationships between eCRF and cognition.

RESULTS

eCRF was positively associated with cognitive speed/flexibility (p = 0.034). When controlling for HOMA-IR, eCRF was no longer associated with cognitive speed/flexibility (p = 0.383). HOMA-IR had a significant indirect effect on the eCRF-cognition relationship (B = 0.025, CI = [0.003,0.051]). eCRF was not associated with working memory (p = 0.236), immediate memory (p = 0.345), or verbal learning/memory (p = 0.650).

CONCLUSION

Among older adults at risk for AD, peripheral insulin resistance mediates the relationship between CRF and cognitive speed.

Effects of acute exercise on memory: Considerations of exercise intensity, post-exercise recovery period and aerobic endurance

Accumulating research demonstrates that acute exercise can enhance long-term episodic memory. However, it is unclear if there is an intensity-specific effect of acute exercise on long-term episodic memory function and whether this is influenced by the post-exercise recovery period, which was the primary objective of this experiment. Another uncertainty in the literature is whether aerobic endurance influences the interaction between exercise intensity and post-exercise recovery period on long-term episodic memory function, which was a secondary objective of this study. With exercise intensity and post-exercise recovery period occurring as within-subject factors, and fitness as a between-subject factor, 59 participants (M_age = 20 years) completed 12 primary laboratory visits. These visits included a 20-min bout of exercise (Control, Moderate, and Vigorous), followed by a recovery period (1, 5, 10, and 15 min) and then a word-list episodic memory task, involving an encoding phase and two long-term recall assessments (20-min and 24-h delayed recall). The primary finding from this experiment was that moderate and vigorous-intensity exercise improved memory function when compared to a non-exercise control. A secondary finding was that individuals with higher levels of aerobic endurance, compared to their lesser fit counterparts, had greater memory performance after exercise (moderate or vigorous) when compared to after a control condition. Additionally, individuals with higher levels of aerobic endurance, compared to their lesser fit counterparts, generally performed better on the memory task with longer post-exercise recovery periods. Future research should carefully consider these parameters when evaluating the effects of acute exercise on long-term episodic memory.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Fitness vs. fatness as determinants of survival in non-institutionalized older adults: The EXERNET multi-center study

BACKGROUND

Physical fitness and body composition are important health indicators, nevertheless their combined pattern inter-relationships and their association with mortality are poorly investigated.

METHODS

This longitudinal study is part of the Spanish EXERNET-Elder project. Person-months follow-up were calculated from the interview date, performed between June 2008 and November 2009, until date of death or censoring on March 2018 (whichever came first). In order to be included, participants had to fulfill the following criteria: 1) be over 65 years old, 2) live independently at home, 3) not suffer dementia and/or cancer and 4) have a BMI above 18.5. Body fat and weight were assessed by a bioelectrical impedance analyzer. Fitness was measured with the Senior Fitness and the one leg static balance tests. The Spanish Death Index was consulted for the death's identification. Cluster analysis was performed to identify Fat-Fit patterns and traditional cut points and percentiles to create the Fat-Fit groups. Cox proportional hazards regression models were used to calculate the hazard ratios of death in clustered Fat-Fit patterns and in traditional Fat-Fit groups.

RESULTS

A total of 2299 older adults (76.8% of women) were included with a baseline mean age of 71.9 ± 5.2 years. A total of 196 deaths (8.7% of the sample) were identified during the 8 years of follow up. Four clustered Fat-Fit patterns (Low fat-Fit, Medium fat-Fit, High fat-Unfit and Low fat-Unfit) and nine traditional Fat-Fit groups emerged. Using the Low fat-Fit pattern as the reference, significantly increased mortality was noted in High fat-Unfit (HR: 1.68, CI: 1.06 - 2.66) and Low fat-Unfit (HR: 2.01, CI: 1.28 - 3.16) groups. All the traditional Fit groups showed lower mortality risk when compared to the reference group (obese-unfit group).

CONCLUSIONS

Physical fitness is a determinant factor in terms of survival in community-dwelling older adults, independently of adiposity levels.

Aerobic Fitness Unrelated to Acquisition of Spatial Relational Memory in College-Aged Adults

While compelling evidence indicates that poorer aerobic fitness relates to impairments in retrieving information from hippocampal-dependent memory, there is a paucity of research on how aerobic fitness relates to the acquisition of such relational information. Accordingly, the present investigation examined the association between aerobic fitness and the rate of encoding spatial relational memory-assessed using a maximal oxygen consumption test and a spatial configuration task-in a sample of 152 college-aged adults. The findings from this investigation revealed no association between aerobic fitness and the acquisition of spatial relational memory. These findings have implications for how aerobic fitness is characterized with regard to memory, such that aerobic fitness does not appear to relate to the rate of learning spatial-relational information; however, given previously reported evidence, aerobic fitness may be associated with a greater ability to recall relational information from memory.