The Effects of Acute Resistance Exercise on Memory, Processing Speed, and Mood State After a Cognitive Challenge.

ABSTRACT: Venezia, AC, Barney, P, Spagnoli, D, Greco-Hiranaka, C, Piepmeier, AT, Smith, JC, and Weiss, LR. The effects of acute resistance exercise on memory, processing speed, and mood state after a cognitive challenge. J Strength Cond Res 37(9): 1738-1745, 2023-Acute moderate-to-vigorous-intensity aerobic exercise has been shown to improve learning and memory, but the effectiveness of acute high-intensity resistance exercise for improving memory is not fully understood. Like acute aerobic exercise, acute resistance exercise increases arousal and circulating catecholamines, mechanisms suggested to mediate the memory-enhancing effects of acute exercise. Furthermore, although acute exercise has been shown to benefit mood state, it is unknown if high-intensity resistance exercise positively influences mood state after a cognitive challenge. In this within-subjects design, subjects (18- to 25-year-old men) completed an approximately 40-minute session of resistance exercise or seated rest. Immediately after, the Automated Neuropsychological Assessment Metrics (ANAM) Code Substitution (CS)-Learning, CS-Immediate Recognition, and CS-Delayed Recognition tasks were completed, followed by the ANAM Mood Scale. There were no significant effects of exercise on recognition memory; however, CS-Learning (attention and processing speed) was better after resistance exercise ( p = 0.03). After the cognitive challenge, restlessness ( p < 0.001), vigor ( p = 0.03), and depression ( p = 0.047) scores were higher after resistance exercise compared with rest; however, after false discovery rate correction, only restlessness remained significantly different between sessions ( q = 0.002), whereas vigor ( q = 0.09) and depression ( q = 0.09) did not. These results suggest that an acute bout of resistance exercise improves attention and processing speed, although it does not improve recognition memory and has mixed effects on mood state in college-aged men.

Greater Semantic Memory Activation After Exercise Training Cessation in Older Endurance-Trained Athletes.

PURPOSE: To examine the effects of a 10-day exercise-training cessation on semantic memory functional activation in older distance runners. METHODS: Ten master runners (62.6 ± 7.0 years) with a long-term endurance-training history (29.0 ± 6.0 years) underwent a 10-day training cessation. Before and immediately after the training cessation, semantic memory activation was measured during the famous name recognition task, using functional magnetic resonance imaging. RESULTS: The 10-day training cessation resulted in greater semantic memory activation in three brain regions, including the left inferior frontal gyrus, parahippocampal gyrus, and inferior semilunar lobule. The 10-day training cessation did not significantly alter famous name recognition task performance. CONCLUSIONS: The findings demonstrate that even a relatively short period without exercise training alters the functional activation patterns of semantic memory-related neural networks. Increased semantic memory activation after training cessation may indicate reduced neural efficiency during successful memory retrieval.

Semantic Memory Activation After Acute Exercise in Healthy Older Adults.

OBJECTIVES: A growing body of research suggests that regular participation in long-term exercise is associated with enhanced cognitive function. However, less is known about the beneficial effects of acute exercise on semantic memory. This study investigated brain activation during a semantic memory task after a single session of exercise in healthy older adults using functional magnetic resonance imaging (fMRI). METHODS: Using a within-subjects counterbalanced design, 26 participants (ages, 55-85 years) underwent two experimental visits on separate days. During each visit, participants engaged in 30 min of rest or stationary cycling exercise immediately before performing a Famous and Non-Famous name discrimination task during fMRI scanning. RESULTS: Acute exercise was associated with significantly greater semantic memory activation (Famous>Non-Famous) in the middle frontal, inferior temporal, middle temporal, and fusiform gyri. A planned comparison additionally showed significantly greater activation in the bilateral hippocampus after exercise compared to rest. These effects were confined to correct trials, and as expected, there were no differences between conditions in response time or accuracy. CONCLUSIONS: Greater brain activation following a single session of exercise suggests that exercise may increase neural processes underlying semantic memory activation in healthy older adults. These effects were localized to the known semantic memory network, and thus do not appear to reflect a general or widespread increase in brain blood flow. Coupled with our prior exercise training effects on semantic memory-related activation, these data suggest the acute increase in neural activation after exercise may provide a stimulus for adaptation over repeated exercise sessions. (JINS, 2019, 25, 557-568).

Improved Cardiorespiratory Fitness Is Associated with Increased Cortical Thickness in Mild Cognitive Impairment.

Cortical atrophy is a biomarker of Alzheimer's disease (AD) that correlates with clinical symptoms. This study examined changes in cortical thickness from before to after an exercise intervention in mild cognitive impairment (MCI) and healthy elders. Thirty physically inactive older adults (14 MCI, 16 healthy controls) underwent MRI before and after participating in a 12-week moderate intensity walking intervention. Participants were between the ages of 61 and 88. Change in cardiorespiratory fitness was assessed using residualized scores of the peak rate of oxygen consumption (V̇O2peak) from pre- to post-intervention. Structural magnetic resonance images were processed using FreeSurfer v5.1.0. V̇O2peak increased an average of 8.49%, which was comparable between MCI and healthy elders. Overall, cortical thickness was stable except for a significant decrease in the right fusiform gyrus in both groups. However, improvement in cardiorespiratory fitness due to the intervention (V̇O2peak) was positively correlated with cortical thickness change in the bilateral insula, precentral gyri, precuneus, posterior cingulate, and inferior and superior frontal cortices. Moreover, MCI participants exhibited stronger positive correlations compared to healthy elders in the left insula and superior temporal gyrus. A 12-week moderate intensity walking intervention led to significantly improved fitness in both MCI and healthy elders. Improved V̇O2peak was associated with widespread increased cortical thickness, which was similar between MCI and healthy elders. Thus, regular exercise may be an especially beneficial intervention to counteract cortical atrophy in all risk groups, and may provide protection against future cognitive decline in both healthy elders and MCI.

Moderate-to-vigorous intensity cycling exercise immediately after visual learning enhances delayed recognition memory performance.

A single bout of acute aerobic exercise has been shown to improve long-term memory, though it is unclear if exercise before learning or after learning is optimal for memory enhancement. Although some research has demonstrated that exercise before learning is ideal, investigations have consistently shown that acute arousal post-learning is a powerful memory enhancer. Therefore, the purpose of this investigation was to compare the effects of self-perceived hard cycling before or after learning on recognition memory for emotional and neutral images, and examine the relationship between central noradrenergic activity and memory performance. Seventy-two males and females (18-35 years of age) participated in this between-subjects study. Participants were randomly assigned to one of the following groups: exercise before learning, exercise after learning, and control. Participants in the exercise groups engaged in 20 min of cycling at a rating of perceived exertion (RPE) of 15 ("hard") on the Borg RPE scale before or after viewing a series of 90 pleasant, unpleasant, and neutral images (30 each). Participants in the control group engaged in no exercise before or after image viewing. At several time points throughout the experiment, saliva was collected to measure salivary alpha amylase (sAA), a marker of central noradrenergic activity. One-week later, recognition memory was assessed where participants viewed 180 images (90 new) and had to identify which images were previously viewed. Participants in the exercise after learning group had significantly higher recognition memory compared to the control group, but this was not seen with exercise before learning. sAA was not correlated with memory in any group, though it did increase during exercise. These results demonstrate that acute self-perceived hard cycling post-learning, but not pre-learning, improves recognition memory, though this was unrelated to the exercise-induced increase in central noradrenergic activity as measured in saliva.

Cardiorespiratory Fitness as a Moderator of Sleep-Related Associations with Hippocampal Volume and Cognition.

The objective of this study was to understand the associations of sleep and cardiorespiratory fitness with hippocampal volume and global cognition among older adults (n = 30, age = 65.8 years, female = 73.3%). Wrist actigraphy provided objective measures of nighttime sleep including sleep duration, average wake bout length (WBL; sleep disturbance), and wake-to-sleep transition probability (WTSP; sleep consolidation). Cardiorespiratory fitness was quantified via cycle exercise using a modified heart rate recovery approach. Magnetic resonance imaging was used to determine hippocampal volume and the Mini-Mental State Examination was used to assess global cognition. Fitness moderated associations of sleep with hippocampal volume and cognitive performance, whereby the association of WBL-an index of poor sleep-with hippocampal atrophy was stronger among less-fit individuals, and the association of sleep duration with cognitive performance was stronger among more-fit individuals. Across the fitness levels, a longer WBL was associated with lower cognitive performance, and a higher WTSP-an index of more consolidated sleep-was associated with greater hippocampal volume. Sleep and fitness were unrelated to the volume of an amygdala control region, suggesting a degree of neuroanatomical specificity. In conclusion, higher cardiorespiratory fitness may attenuate sleep disturbance-related hippocampal atrophy and magnify the cognitive benefits of good sleep. Prospective studies are needed to confirm these findings.

Microstructural Plasticity in the Hippocampus of Healthy Older Adults after Acute Exercise.

INTRODUCTION: The hippocampus experiences structural and functional decline with age and is a critical region for memory and many cognitive processes. Exercise is beneficial for the aging brain and shows preferential benefits for hippocampal volume, activation, and memory-related cognitive processes. However, research thus far has primarily focused on the effects of exercise on long-term volumetric changes in the hippocampus using structural magnetic resonance imaging. Critically, microstructural alterations within the hippocampus over short time intervals are associated with neuroplasticity and cognitive changes that do not alter its volume but are still functionally relevant. However, it is not yet known if microstructural neuroplasticity occurs in the hippocampus in response to a single session of exercise. METHODS: We used a within-subject design to determine if a 30-min bout of moderate-intensity aerobic exercise altered bilateral hippocampal diffusion tensor imaging measures in healthy older adults (n = 30) compared with a seated rest control condition. RESULTS: Significantly lower fractional anisotropy and higher mean diffusivity were found after exercise relative to seated rest within the bilateral hippocampus, and this effect was driven by higher radial diffusivity. No significant differences in axial diffusivity were observed. CONCLUSIONS: These findings suggest that a single exercise session can lead to microstructural alterations in the hippocampus of healthy older adults. These differences may be associated with changes in the extracellular space and glial, synaptic, and dendritic processes within the hippocampus. Repeated microstructural alterations resulting from acute bouts of exercise may accumulate and precede larger volumetric and functional improvements in the hippocampus.

Impact of exercise on older adults' mood is moderated by sleep and mediated by altered brain connectivity.

Older adults comprise the fastest growing global demographic and are at increased risk of poor mental health outcomes. Although aerobic exercise and sleep are critical to the preservation of emotional well-being, few studies have examined their combined mood-enhancing effects, or the potential neural mechanisms underlying these effects. Here, we used a randomized crossover design to test the impact of acute exercise on mood and the intrinsic functional connectivity (iFC) of the cingulo-opercular network in physically healthy older adults. Wrist actigraphy provided objective indices of sleep. Results revealed that 30 min of moderate-intensity aerobic exercise acutely enhanced positive affect (PA) and reduced iFC between the cingulo-opercular network and the hippocampus. Both effects were magnified among older adults with greater sleep disturbance. Exercise-induced changes in hippocampal iFC mediated relations between sleep disturbance and exercise-induced increases in PA. These findings provide evidence that aerobic exercise enhances mood, that it does so by altering connectivity between the anterior insula-a key hub in the cingulo-opercular network-and the hippocampus and that lower sleep quality is a stronger predictor of these effects among older adults. These observations underscore the benefits of moderate-intensity exercise-a safe and scalable behavioral intervention-and provide new clues about the neural circuitry underlying the interactive effects of sleep and exercise on mood.

A single bout of hard RPE-based cycling exercise increases salivary alpha-amylase.

Exercise exerts beneficial effects on cognition, in part by stimulating an arousal response that includes the release of catecholamines. Sympathetic nervous system arousal and activation of the noradrenergic system in particular may enhance cognitive performance. Measurement of salivary alpha-amylase, a non-invasive biomarker of central noradrenergic activity, is a promising avenue for characterizing the arousal-mediated effects of exercise on cognition. However, the effectiveness of high-intensity acute exercise, and the time course of sAA concentrations following exercise, has not been clearly described. The purpose of this study was to determine the effects of 20 min of perceived exertion-based high-intensity cycling exercise on salivary alpha-amylase levels in healthy young adults. We utilized a repeated-measures design to examine the sAA response to cycling exercise, rest, and an emotional picture viewing task. Thirty-two participants between the ages of 18-30 viewed pleasant, neutral, and unpleasant pictures from the International Affective Picture System. Before and after the task, participants completed either 20 min of seated rest or cycling exercise at an intensity corresponding to 15 ("hard") on Borg's Ratings of Perceived Exertion scale. Salivary alpha-amylase was assessed at time points immediately before and after rest, exercise, and the picture viewing task. Exercise elicited a robust increase in salivary alpha-amylase approximately six times higher than that induced by emotional picture viewing. Importantly, the observed exercise-induced increase in salivary alpha-amylase returned to a level comparable to baseline after ten minutes. These findings have meaningful implications for future work characterizing the relationship between exercise and arousal-mediated effects on cognitive performance.

Brain activation during executive control after acute exercise in older adults.

Previous work has shown that aerobic exercise training is associated with regional changes in functional activation and improved behavioral outcomes during the Flanker task. However, it is unknown whether acute aerobic exercise has comparable effects on brain activation during the Flanker task. The aim of this study was to examine the effects of an acute bout of moderate-intensity bicycle exercise on Flanker task functional activation and behavioral performance in older adults. Thirty-two healthy older adults (66.2 ±â€¯7.3 years) performed two experimental visits that included 30-min of aerobic exercise and a rest condition on separate days. After each condition, participants performed the Flanker task during an fMRI scan. Significantly greater functional activation (incongruent > congruent) was found in the left inferior frontal gyrus and inferior parietal lobule after exercise compared to rest. A main effect of exercise was also observed on Flanker task performance with greater accuracy in both incongruent and congruent trials, suggesting the effects of acute exercise on Flanker performance are general across Flanker trial types. Conversely, greater executive control-related functional activations after performing a single session of exercise suggests enhanced functional processing while engaging in task conditions requiring disproportionately greater amounts of executive control.

Resting Cerebral Blood Flow After Exercise Training in Mild Cognitive Impairment.

BACKGROUND: Exercise training has been associated with greater cerebral blood flow (CBF) in cognitively normal older adults (CN). Alterations in CBF, including compensatory perfusion in the prefrontal cortex, may facilitate changes to the brain's neural infrastructure. OBJECTIVE: To examine the effects of a 12-week aerobic exercise intervention on resting CBF and cognition in CN and those with mild cognitive impairment (MCI). We hypothesized individuals with MCI (versus CN) would exhibit greater whole brain CBF at baseline and that exercise would mitigate these differences. We also expected CBF changes to parallel cognitive improvements. METHODS: Before and after a 12-week exercise intervention, 18 CN and 17 MCI participants (aged 61-88) underwent aerobic fitness testing, neuropsychological assessment, and an MRI scan. Perfusion-weighted images were collected using a GE 3T MR system. Repeated measures analyses of covariance were used to test within- and between-group differences over time, followed by post-hoc analyses to examine links between CBF changes and cognitive improvement. RESULTS: At baseline, individuals with MCI (versus CN) exhibited significantly elevated perfusion in the left insula. Twelve weeks of aerobic exercise reversed this discrepancy. Additionally, exercise improved working memory (measured by the Rey Auditory Verbal Learning Test) and verbal fluency (measured by the Controlled Oral Word Association Test) and differentially altered CBF depending on cognitive status. Among those with MCI, decreased CBF in the left insula and anterior cingulate cortex was associated with improved verbal fluency. CONCLUSIONS: Exercise training alters CBF and improves cognitive performance in older adults with and without cognitive impairment. Future studies must evaluate the mediating effects of CBF on the association between exercise training and cognition.

Caudate Volume Mediates the Interaction between Total Sleep Time and Executive Function after Acute Exercise in Healthy Older Adults.

Although both exercise and sleep are significant lifestyle factors in cognitive aging, the interaction of these two factors with respect to cognition remains to be determined. Also, little is known regarding the role of the basal ganglia (BG) in cognitive aging despite its involvement in both sleep and executive function. The primary objective of this study was to investigate the interaction between sleep and acute exercise on executive function performance, and secondarily, to assess if BG volume mediates this interaction. Thirty healthy older adults (65.8±7.3 years) completed 30 minutes of seated rest or moderate-intensity cycling exercise on different days. Structural MRI was used to assess the volumes of BG components including caudate, putamen, and globus pallidus shortly after the experimental conditions. Approximately 90 minutes after each condition, the Stroop task was administered to measure executive function. To examine sleep, participants wore a wrist actigraph for 8.0±3.6 days prior to the first experimental session. Results revealed that while longer total sleep time (TST) was associated with shorter Stroop response time (RT), shorter TST was associated with longer RT after exercise, compared to rest, for both congruent (p = 0.029) and incongruent (p = 0.022) trials. Longer TST was correlated with greater caudate volume, and greater caudate volume was associated with exercise-related improvement in Stroop incongruent RT. Ultimately, we found that the association between longer sleep duration and faster processing speed after acute exercise was mediated by greater caudate volume. These findings suggest that TST is an important factor for acute exercise-induced cognitive improvements in older adults, and that our study is a first step in understanding the interactive effects of these important lifestyle factors in cognitive aging that might simultaneously be addressed to promote healthy cognitive aging. Future studies should examine the interactive effects of sleep and chronic exercise on cognitive function, and whether BG volume might also mediate this interaction.

Exercise Training and Functional Connectivity Changes in Mild Cognitive Impairment and Healthy Elders.

BACKGROUND: Effective interventions are needed to improve brain function in mild cognitive impairment (MCI), an early stage of Alzheimer's disease (AD). The posterior cingulate cortex (PCC)/precuneus is a hub of the default mode network (DMN) and is preferentially vulnerable to disruption of functional connectivity in MCI and AD. OBJECTIVE: We investigated whether 12 weeks of aerobic exercise could enhance functional connectivity of the PCC/precuneus in MCI and healthy elders. METHODS: Sixteen MCI and 16 healthy elders (age range = 60-88) engaged in a supervised 12-week walking exercise intervention. Functional MRI was acquired at rest; the PCC/precuneus was used as a seed for correlated brain activity maps. RESULTS: A linear mixed effects model revealed a significant interaction in the right parietal lobe: the MCI group showed increased connectivity while the healthy elders showed decreased connectivity. In addition, both groups showed increased connectivity with the left postcentral gyrus. Comparing pre to post intervention changes within each group, the MCI group showed increased connectivity in 10 regions spanning frontal, parietal, temporal and insular lobes, and the cerebellum. Healthy elders did not demonstrate any significant connectivity changes. CONCLUSION: The observed results show increased functional connectivity of the PCC/precuneus in individuals with MCI after 12 weeks of moderate intensity walking exercise training. The protective effects of exercise training on cognition may be realized through the enhancement of neural recruitment mechanisms, which may possibly increase cognitive reserve. Whether these effects of exercise training may delay further cognitive decline in patients diagnosed with MCI remains to be demonstrated.

Hippocampal and Cerebral Blood Flow after Exercise Cessation in Master Athletes.

While endurance exercise training improves cerebrovascular health and has neurotrophic effects within the hippocampus, the effects of stopping this exercise on the brain remain unclear. Our aim was to measure the effects of 10 days of detraining on resting cerebral blood flow (rCBF) in gray matter and the hippocampus in healthy and physically fit older adults. We hypothesized that rCBF would decrease in the hippocampus after a 10-day cessation of exercise training. Twelve master athletes, defined as older adults (age ≥ 50 years) with long-term endurance training histories (≥15 years), were recruited from local running clubs. After screening, eligible participants were asked to cease all training and vigorous physical activity for 10 consecutive days. Before and immediately after the exercise cessation period, rCBF was measured with perfusion-weighted MRI. A voxel-wise analysis was used in gray matter, and the hippocampus was selected a priori as a structurally defined region of interest (ROI), to detect rCBF changes over time. Resting CBF significantly decreased in eight gray matter brain regions. These regions included: (L) inferior temporal gyrus, fusiform gyrus, inferior parietal lobule, (R) cerebellar tonsil, lingual gyrus, precuneus, and bilateral cerebellum (FWE p < 0.05). Additionally, rCBF within the left and right hippocampus significantly decreased after 10 days of no exercise training. These findings suggest that the cerebrovascular system, including the regulation of resting hippocampal blood flow, is responsive to short-term decreases in exercise training among master athletes. Cessation of exercise training among physically fit individuals may provide a novel method to assess the effects of acute exercise and exercise training on brain function in older adults.