Acute exercise on memory: application of the retrieval-induced forgetting paradigm.

Accumulating research has shown that acute exercise can enhance memory function. Although counterintuitive, acute exercise may also facilitate aspects of forgetting. Specifically, retrieving a subset of items from memory can facilitate the retention of retrieved items (retrieval practice) and inhibit the subsequent retrieval of non-retrieved items from the same category (retrieval-induced forgetting; RIF). Given that acute exercise has been shown to enhance cognition-related inhibition, acute exercise may facilitate RIF, which was evaluated in three experiments. In Experiment 1, a sample of 180 young adults completed either a control (N = 60), moderate-intensity acute exercise (N = 57), or vigorous-intensity acute exercise session (N = 63). Both acute exercise sessions lasted 20 min and occurred prior to the study list. Participants then completed a standard RIF protocol, with the final test occurring via a recognition task. Acute exercise, regardless of intensity, had no effect on RIF. Experiment 2 (N = 225) was similar to Experiment 1 but used a cued recall final test, and also showed no effects of acute exercise on RIF. In Experiment 3 (N = 158), two cued recall tests were implemented, with acute exercise occurring between the two tests. Acute exercise, but not a control scenario, preserved the RIF effect across the cued recall assessments. These findings suggest that acute exercise prior to study may not influence RIF, but when positioned between two recall assessments, acute exercise may preserve the RIF effect over time.

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 (Mage = 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.

Age-varying association between depression and cognitive function among a national sample of older U.S. immigrant adults: the potential moderating role of physical activity.

OBJECTIVES: This study aimed to (1) investigate age-associated trends in depression and cognition, (2) determine whether the association between depression and cognition varies across age, and (3) test whether this association is moderated by different levels of physical activity among older U.S. immigrant adults aged 60 to 80 years. METHODS: Using national data on elderly U.S. immigrants (N = 375) from the 2011-2014 NHANES, we employed weighted intercept-only linear time-varying effect modeling (TVEM) and weighted linear TVEM to address our research questions. RESULTS: Weighted intercept-only linear TVEM indicated no trend in depression, but its mean peaked at age 67. Cognition consistently decreased with age, reaching its lowest point at age 78. Weighted linear TVEM revealed a significant inverse association between depression and cognition at some age ranges, with the strongest association at around age 66. Yet, we did not find the moderational relation of physical activity to this age-varying association. CONCLUSIONS: Although we observed a significant inverse relationship between depression and cognition at a certain age point, physical activity did not moderate the age-varying association. Understanding of age-varying effects on the depression-cognition interaction will promote prevention efforts targeting aging immigrant populations at highest risk for these health outcomes. Further work is needed to test moderating effects of other health behaviors on this association across age.Supplemental data for this article is available online at https://doi.org/10.1080/13607863.2022.2056139 .

Association among length of residence, physical activity, and obesity in the US immigrants: A regression-based mediation analysis.

OBJECTIVES: To examine the mediated relationship between objectively measured obesity, accelerometer-based moderate-to-vigorous physical activity (MVPA), and length of residence among US immigrants. METHODS: A total of 885 adults (≥18 years) who were born outside the United States from the 2003 to 2006 National Health and Nutrition Examination Survey were included in the analysis. The participants were categorized into two groups (i.e., living in the United States ≥15 years vs. <15 years). MVPA time (minutes/day) was measured by ActiGraph accelerometry. Obesity was defined as body fat percentage measured by dual-energy X-ray absorptiometry. Regression-based mediation analysis was conducted using SURVEY procedures in SAS version 9.4. RESULTS: When controlling for covariates, immigrants living in the United States for ≥15 years were significantly less likely to spend time participating in MVPA (c; ß = -4.50, p = .04), and more likely to be at high risk of obesity (a; ß = 1.70, p = .01) compared to those living in the United States for <15 years. Also, the relationship between obesity and MVPA was statistically significant (b; ß = -0.80, p = .003). Length of residence was indirectly associated with MVPA (ab; ß = -1.37, p = .03), suggesting that obesity mediated the association of length of residence on MVPA (c'; ß = -3.13, p = .20). CONCLUSIONS: Obesity mediated the association between length of residence and MVPA in the US immigrants. These findings may encourage long-term US immigrants to prevent and treat obesity for increasing the amount of MVPA time.

Motor behavior-induced prefrontal cortex activation and episodic memory function.

BACKGROUND: The objective of this paper was to evaluate the potential individual and combined effects of acute exercise coupled with bilateral interhemispheric activation on episodic memory function. Six experiments were conducted. METHODS: Experiment 1 was a within-subject, counterbalanced experiment. Participants completed four visits, including 1) exercise and saccadic eye movements, 2) exercise only, 3) saccadic eye movements only, and 4) no exercise and no saccadic eye movements (control). A word-list memory assessment was employed, including a long-term (20-min delay) memory evaluation. In Experiment 2, we evaluated the effects of saccadic eye movements on prefrontal cortex oxygenation, a proxy for neuronal activity. Similarly, in our third experiment, we evaluated the effects of acute exercise on prefrontal cortex oxygenation. Thus, experiments 2 and 3 were employed to provide mechanistic insights from the results shown in experiment 1. Experiment 4 replicated Experiment 1, but instead of increasing prefrontal cortex activation via saccadic eye movements, we used a fist clenching protocol. Experiment 5 evaluated the effects of fist clenching on prefrontal cortex oxygenation. RESULTS: Collectively, these 5 experimental studies showed that acute exercise (Experiment 1), saccadic eye movements (Experiment 1), and fist clenching (Experiment 4) enhanced memory function, and that acute exercise (Experiment 3), saccadic eye movements (Experiment 2) and fist clenching (Experiment 5) all increased prefrontal cortex oxygenation. Experiment 6 demonstrated that prefrontal cortex oxygenation was positively associated with episodic memory function. CONCLUSION: These six experiments suggest that several behaviors, such as acute exercise, saccadic eye movements and fist clenching may improve memory function and may, potentially, do so via increases in prefrontal cortex oxygenation.

Exercise influences episodic memory via changes in hippocampal neurocircuitry and long-term potentiation.

The ability to learn, store and recapture information about unique personal experiences is referred to as episodic memory and is sustained by a network of brain areas that are nestled within the medial temporal lobe (MTL) and associated networks. Human and animal data demonstrate that these structural components are influential in the organization and processing of incoming information. Strengthening the cellular and neural communication within the aforementioned components of the brain, called long-term potentiation (LTP), is considered a driving force underscoring the ability to recapture information about unique personal experiences. This process can be enhanced by exercise, thus facilitating improvements in episodic memory. This narrative review discusses the interrelationships (and underlying mechanisms) between exercise, LTP and episodic memory.

Effects of Exercise on Long-Term Potentiation in Neuropsychiatric Disorders.

Various neuropsychiatric conditions, such as depression, Alzheimer's disease, and Parkinson's disease, demonstrate evidence of impaired long-term potentiation, a cellular correlate of episodic memory function. This chapter discusses the mechanistic effects of these neuropsychiatric conditions on long-term potentiation and how exercise may help to attenuate these detrimental effects.

Effects of Exercise on Memory Interference in Neuropsychiatric Disorders.

There are several mechanisms that cause memory impairment, including motivated forgetting, active forgetting, natural decay, and memory interference. Interference occurs when one is attempting to recall something specific, but there is conflicting information making it more difficult to recall the target stimuli. In laboratory settings, it is common to measure memory interference with paired associate tasks-usually utilizing the AB-CD, AB-AC, AB-ABr, or AB-DE AC-FG method. Memory impairments are frequent among those with neuropsychiatric disorders such as depression, schizophrenia, and multiple sclerosis. The memory effects of each condition differ, but are all related to alterations in brain physiology and general memory deterioration. Exercise, or physical activity, has been demonstrated to attenuate memory interference in some cases, but the mechanisms are still being determined. Further research is needed on memory interference, in regard to exercise and neuropsychiatric disorders.

Integrity of the cortico-spinal tract is associated with physical activity.

Background and purpose: Despite the primary motor efferent role of the cortico-spinal tract (CST), it is hardly understood whether the amount of physical activity is associated with the integrity of the CST.Materials and methods: We examined the association between the amount of physical activity and the integrity of the CST, using Diffusion Tensor Imaging (DTI) data from 465 individuals. The CST was segmented by probabilistic tractography and the association of the fractional anisotropy (FA) within was tested against physical activity (PA) assessed by moderate-intensity physical activity of the International Physical Activity Questionnaire.Results: The FA and PA showed a positive association. Post-hoc analyses showed that the radial diffusivity (RD) of the CST was negatively associated with PA, suggesting a potential association with preserved myelination with PA.Conclusion: This study shows that the integrity of the CST is associated with its traffic in the general population.

Hypothesized Mechanisms Through Which Exercise May Attenuate Memory Interference.

In this paper we introduce a mechanistic model through which exercise may enhance episodic memory, specifically via attenuating proactive and retroactive memory interference. We discuss the various types of memory, different stages of memory function, review the mechanisms behind forgetting, and the mechanistic role of exercise in facilitating pattern separation (to attenuate memory interference).

Association of cardiorespiratory fitness on interhemispheric hippocampal and parahippocampal functional connectivity.

Interhemispheric functional connectivity is associated with cognitive functioning. Although previous work has evaluated the association of cardiorespiratory fitness on cognitive function, there has been a limited investigation of the association of cardiorespiratory fitness on the functional connectivity of memory-related brain structures. As such, the objective of this study was to examine the association between cardiorespiratory fitness and parahippocampal and hippocampal interhemispheric functional connectivity. Data from the Nathan Kline Institute-Rockland Sample (NKI-RS) were utilized. Our analysis consisted of 284 participants (Mage  = 43 years; 62% female). Cardiorespiratory fitness was objectively measured using a cycle ergometer protocol. Parahippocampal and hippocampal interhemispheric functional connectivity were assessed from fMRI. Higher cardiorespiratory fitness was associated with greater parahippocampal (ß = 0.004; CI, 0.00009 to 0.008, p = 0.04), but not hippocampal (ß = 0.001; CI, -0.002 to 0.005, p = 0.44) interhemispheric functional connectivity. In conclusion, enhanced cardiorespiratory fitness may facilitate parahippocampal interhemispheric functional connectivity.

The Beneficial Effects of Mind-Body Exercises for People With Mild Cognitive Impairment: a Systematic Review With Meta-analysis.

OBJECTIVE: To objectively evaluate the most common forms of mind-body exercise (MBE) (tai chi, yoga, qigong) on cognitive function among people with mild cognitive impairment (MCI). DATA SOURCES: We searched 6 electronic databases (Scopus, PubMed, PsycINFO, WanFang, Web of Science, CNKI) from inception until September 2018. STUDY SELECTION: Nine randomized controlled trials and 3 nonrandomized controlled trials were included for meta-analysis. DATA EXTRACTION: Two researchers independently performed the literature searches, study selection, data extraction, and methodological quality assessment using the revised Physiotherapy Evidence Database (PEDro) scale. DATA SYNTHESIS: The pooled effect size (standardized mean difference [SMD]) was calculated while random-effect model was selected. Overall results of the meta-analysis (N=1298 people with MCI) indicated that MBE significantly improved attention (SMD=0.39, 95% confidence interval [CI] 0.07-0.71, P=.02, I2=31.6%, n=245), short-term memory (SMD=0.74, 95% CI 0.57-0.90, P<.001, I2=0%, n=861), executive function (SMD=-0.42, 95% CI -0.63 to -0.21, P<.001, I2=38.54%, n=701), visual-spatial/executive function (SMD=0.35, 95% CI 0.07-0.64, P<.05, I2=0%, n=285), and global cognitive function (SMD=0.36, 95% CI 0.2-0.52, P<.001, I2=15.12%, n=902). However, the significant positive effect on cognitive processing speed was not observed following MBE interventions (SMD=0.31, 95% CI -0.01 to 0.63, P=.054, I2=28.66%, n=233). CONCLUSIONS: Study findings of this meta-analysis suggest that MBE have the potential to improve various cognitive functions in people with MCI.

Prevalence, patterns, and correlates of physical activity in Nepal: findings from a nationally representative study using the Global Physical Activity Questionnaire (GPAQ).

BACKGROUND: The promotion of a physically active lifestyle might help address the increasing burden of non-communicable diseases in Nepal. However, there is a lack of nationally representative estimates of physical activity (PA) prevalence in Nepal. The aim of this nationwide cross-sectional study was to determine domain-specific PA levels and the association of socio-demographic and lifestyle characteristics with total PA among Nepalese adults aged 15-69 years. METHODS: The data were collected using self-administered questionnaires in a nationally representative sample of 4143 adults (66.5% females), comprised of both rural and urban populations in Nepal. PA levels were assessed using the Global Physical Activity Questionnaire (GPAQ). RESULTS: Based on self-reported estimates, around 97% (95% confidence interval [CI]: 96-98%) of men and 98% (95% CI: 98-99%) of women were found to meet the recommended levels of PA. Both men and women reported high occupational PA, whilst most participants of both sexes did not report engaging in any leisure-time PA. A multiple regression analysis showed that less self-reported total PA was associated with older age, higher level of education, urban place of residence, never been married, being underweight, and smoking in both sexes and with overweight and obesity in males (p < 0.05 for all). CONCLUSION: According to self-reported estimates, majority of Nepalese men and women are meeting the recommended levels of PA. The total self-reported PA in Nepalese adults is high, because many of them have labour intensive jobs. Although older age, higher level of education, urban place of residence, never been married, being underweight, and smoking in both sexes, as well as overweight and obesity in males were inversely associated with self-reported PA, the overall level of PA in all these groups was very high. Given the high overall self-reported PA found in the current study, promoting more PA in Nepal may not be as important as in some other countries; not even in the population groups for which we found a negative association with PA. Nevertheless, future studies should examine whether a more balanced distribution of occupational and leisure-time PA would promote better health among Nepalese adults.

Association Between Motor Skills and Musculoskeletal Physical Fitness Among Preschoolers.

OBJECTIVE: Previous work is conflicted regarding the relationship between motor skill development and physical activity. One potential explanation for this equivocality is the difficulty and lack of precision in physical activity measurement, particularly within preschool populations. Our exploration of plank performance as a proxy measure for fitness addresses a void in the literature, as few studies have investigated the role of motor skill development on fitness. The purpose of this study was to evaluate the potential relationship between motor skill level and musculoskeletal endurance (via the plank test). METHODS: Data from the 2012 National Youth Fitness Survey were used, which included 224 preschool-aged children (3-5 years). Motor skill level was assessed from the Test of Gross Motor Development-Second Edition (TGMD2). Motor skill parameters included general motor skills, locomotor skills, and object control skills. RESULTS: Within this nationally representative sample of preschoolers, increased motor skills were positively associated with plank performance [General Motor Skills (ß = 0.45; 95% CI 0.31-0.59), locomotor skills (ß = 1.88; 95% CI 1.15-2.61), and object control skills (ß = 2.05; 95% CI 1.11-2.98)]. CONCLUSION: Motor skill level in this national preschool sample was associated with musculoskeletal endurance. Thus, future interventions should aim to develop and refine motor skills among preschoolers.

Physical Activity, Muscle-Strengthening Activities, and Systemic Inflammation Among Retinopathy Patients.

OBJECTIVE: We evaluated the specific association between muscle-strengthening activity (MSA) and accelerometer-assessed physical activity on systemic inflammation among retinopathy patients in the United States. METHODS: Data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) were used to identify 157 retinopathy patients between 40 and 85 years of age with complete data on select study variables. MSA was assessed via self-report. Participation in moderate-to-vigorous physical activity (MVPA) was determined from objective accelerometer data. Systemic inflammation was assessed using C-reactive protein (CRP), which was quantified using latex-enhanced nephelometry. Nonproliferative retinopathy was determined using Early Treatment Diabetic Retinopathy Study grading criteria, as well as objective retinal imaging assessments using the Canon Non-Mydriatic Retinal Camera CR6-45NM. Individuals were excluded if they had been diagnosed with coronary artery disease, congestive heart failure, heart attack, or stroke. RESULTS: MVPA (ß = -0.004, 95% CI -0.007 to -0.001, P = 0.006) but not MSA (ß = -0.0001, 95% CI -0.002 to 0.001, P = 0.86) was associated with lower CRP levels. Additionally, for a more substantive 30 minutes/day increase in MVPA, there was a corresponding 0.12 mg/dL decrease in CRP. CONCLUSION: In this nationally representative sample of adults, only individuals who engaged in higher levels of MVPA had lower CRP levels, which is indicative of reduced systemic inflammation. MSA was not associated with systemic inflammation among this cohort. Our findings suggest that MVPA is inversely associated with systemic inflammation among retinopathy patients, which is noteworthy because increased systemic inflammation may facilitate retinopathic severity.

Objectively Measured Physical Activity and All-Cause Mortality Among Cancer Survivors: National Prospective Cohort Study.

OBJECTIVE: The understanding of the effects of physical activity on all-cause mortality among cancer survivors is limited. We attempted to draw a relation between physical activity and survival among those with a diagnosis of cancer. METHODS: Data from the 2003-2006 National Health and Nutrition Examination Survey was used, with follow-up through 2011. A total of 515 adult cancer survivors wore an accelerometer for ≥4 days. RESULTS: After adjusting for age, sex, race/ethnicity, poverty level, cotinine, C-reactive protein, body mass index, and comorbid illness, participants had a 15% reduced hazard rate (hazard rate 0.85, 95% confidence interval 0.73-0.99, P < 0.001) for every 60-minute/day increase in physical activity. CONCLUSIONS: Physical activity may have a protective effect on survival among cancer survivors.

Exercise and cardiorespiratory fitness on subjective memory complaints.

The purpose of this study was to examine the association between exercise and estimated cardiorespiratory fitness on subjective memory complaints in young adults. Four-hundred and 64 young adult college students (18-35 yrs) completed an online survey. Exercise behavior was assessed from the Physical Activity Vital Signs Questionnaire. Cardiorespiratory fitness was evaluated from an algorithm that included an assessment of age, gender, body mass index, waist circumference, resting heart rate, habitual physical activity behavior, and smoking status. Subjective memory complaints were assessed using the Prospective-Retrospective Memory Questionnaire. Subjective memory complaints were common among this young adult sample. However, exercise was not statistically significantly associated with prospective (ß = -0.002, P = 0.25) or retrospective (ß = -0.001, P = 0.26) memory complaints. Results were similar for cardiorespiratory fitness. In conclusion, we did not observe an association between exercise and estimated cardiorespiratory fitness on subjective memory complaints in young adults.

The Association of Cardiorespiratory Fitness on Memory Function: Systematic Review.

Background and Objectives: Cardiorespiratory fitness is an important predictor of cardiovascular and cardiometabolic health. To extend our knowledge on the health effects associated with cardiorespiratory fitness, the objective of this study was to evaluate the association of cardiorespiratory fitness on memory function. Materials and Methods: Embase/PubMed, Web of Science, Google Scholar, Sports Discus, and PsychInfo databases were searched. Inclusionary criteria included: (1) were conducted among adult humans (18+ years), (2) evaluated cardiorespiratory fitness as the independent variable, (3) measured cardiorespiratory fitness with an objective device (e.g., indirect calorimetry), (4) evaluated memory function (any type) as the outcome measure, and (5) included either a cross-sectional, prospective, or experimental-study design. Information on the participant's characteristics, study design, cardiorespiratory fitness assessment, memory type, whether the study statistically controlled for exercise behavior, and study results were extracted. The relationship between cardiorespiratory fitness and memory was synthesized while considering the data extraction parameters. Results: In total, 17 articles met the inclusionary criteria, including two prospective cohort studies and 15 cross-sectional studies. The main findings of this review are twofold: (1) across the 17 evaluated studies, 15 (88.2%) studies demonstrated some evidence of a positive association between cardiorespiratory fitness (CRF) and memory function, and (2) none of these 17 studies statistically controlled for physical activity behavior. Conclusion: CRF appears to be positively associated with memory function, however, it is uncertain as to whether this association occurs independently of physical activity or is mediated via physical activity behavior.

Acute Exercise Intensity and Memory Function: Evaluation of the Transient Hypofrontality Hypothesis.

Background and Objective: The transient hypofrontality hypothesis predicts that memory function will be impaired during high-intensity exercise, as a result of a need for metabolic and cognitive resources to be allocated toward sustaining movement, as opposed to performing a cognitive task. The purpose of these experiments was to evaluate this transient hypofrontality hypothesis. Materials and Methods: Experiment 1 involved participants (n = 24; Mage = 21.9 years) completing four counterbalanced visits. Two visits evaluated working memory function, either at rest or during a high-intensity bout of acute exercise. The other two visits evaluated episodic memory function, either at rest or during a high-intensity bout of acute exercise. Experiment 2 (n = 24; Mage = 20.9 years) extended Experiment 1 by evaluating memory function (working memory) across 4 counterbalanced conditions, including at rest and during light (30% of heart rate reserve; HRR), moderate (50% HRR) and high-intensity (80% HRR) acute exercise. Results: Experiment 1 demonstrated that, when compared to rest, both working memory and episodic memory were impaired during high-intensity acute exercise. Experiment 2 replicated this effect, but then also showed that, unlike high-intensity acute exercise, memory function was not impaired during low- and moderate-intensity acute exercise. Conclusions: Our experiments provide support for the transient hypofrontality hypothesis. Both working memory and episodic memory are impaired during high-intensity acute exercise. Working memory does not appear to be impaired during lower exercise intensities.

High-Intensity Acute Exercise and Directed Forgetting on Memory Function.

BACKGROUND AND OBJECTIVES: Despite accumulating research demonstrating that acute exercise may enhance memory function, very little research has evaluated whether acute exercise can effectuate intentional directed forgetting (DF), an adaptative strategy to facilitate subsequent memory performance. MATERIALS AND METHODS: A three-arm parallel-group randomized controlled intervention was employed. Participants were randomized into one of three groups, including: (1) exercise plus DF (Ex + DF), (2) DF (directed forgetting) only (DF) and (3) R (remember) only (R). The acute bout of exercise included 15 min of high-intensity treadmill exercise. The memory assessment involved the presentation of two-word lists. After encoding the first word list, participants were either instructed to forget all of those words (DF) or to remember them. Following this, participants encoded the second word list. RESULTS: We observed a statistically significant main effect for list F(1, 57) = 12.27, p < 0.001, η2p = 0.18, but no main effect for group F(2, 57) = 1.32, p = 0.27, η2p = 0.04, or list by group interaction, F(2, 57) = 2.89, p = 0.06, η2p = 0.09. CONCLUSION: This study demonstrates a directed forgetting effect in that cueing an individual to forget a previously encoded list of items facilitates memory performance on a subsequent list of items. However, we failed to demonstrate any beneficial effect of acute exercise in facilitating directed forgetting. These findings are discussed in the context of directed forgetting theories, particularly the attention inhibition mechanism, as well as the timing of the acute bout of exercise.