High intensity exercise decreases global brain glucose uptake in humans

Endogenous Opioids and Exercise-Related Hypoalgesia: Modern Models, Measurement, and Mechanisms of Action

This chapter will focus on the role exercise appears to have on activation and modulating factors within the central nervous system related to endogenous like opioids and its possible contribution to exercise-induced hypoalgesia. The implications for the exercise-mediated alterations of CNS activation factors related to opioids, specifically endorphins and enkephalins, will be presented. In this update, we discuss utilization of new technology and methods to monitor mechanisms of opioid involvement to suggest their contribution with exercise mediated hypoalgesia as well as their relationships to alterations of perceptions of pain and mood. Several special populations were included to suggest that not all individuals will respond to the exercise by mediating hypoalgesia. Factors that may confound the current understanding and suggestions from the recent literature will be presented as well as suggestions for future investigations.

Exercise Modifies the Brain Metabolic Response to Chronic Cocaine Exposure Inhibiting the Stria Terminalis

It is well known that exercise promotes health and wellness, both mentally and physiologically. It has been shown to play a protective role in many diseases, including cardiovascular, neurological, and psychiatric diseases. The present study examined the effects of aerobic exercise on brain glucose metabolic activity in response to chronic cocaine exposure in female Lewis rats. Rats were divided into exercise and sedentary groups. Exercised rats underwent treadmill running for six weeks and were compared to the sedentary rats. Using positron emission tomography (PET) and [18F]-Fluorodeoxyglucose (FDG), metabolic changes in distinct brain regions were observed when comparing cocaine-exposed exercised rats to cocaine-exposed sedentary rats. This included activation of the secondary visual cortex and inhibition in the cerebellum, stria terminalis, thalamus, caudate putamen, and primary somatosensory cortex. The functional network of this brain circuit is involved in sensory processing, fear and stress responses, reward/addiction, and movement. These results show that chronic exercise can alter the brain metabolic response to cocaine treatment in regions associated with emotion, behavior, and the brain reward cascade. This supports previous findings of the potential for aerobic exercise to alter the brain's response to drugs of abuse, providing targets for future investigation. These results can provide insights into the fields of exercise neuroscience, psychiatry, and addiction research.

Medium chain triglycerides with a C8:C10 ratio of 30:70 enhances cognitive performance and mitigates the cognitive decline associated with prolonged exercise in young and healthy adults

INTRODUCTION

Prolonged exercise has been linked to a decline in cognitive function due to a variety of factors, such as a drop in oxygen in the prefrontal cortex and an increase in stress hormones and neurotransmitters. Medium chain triglycerides (MCTs) may possibly offset this decline as they provide energy for the brain via both direct and indirect pathways, alongside promoting chronic physiological adaptations within the brain.

METHODS

Participants were divided into two groups; MCT (n = 9) and Placebo (n = 10). The MCT gels contained 6 g of MCT with a C8:C10 ratio of 30:70, whereas the placebo gels contained carbohydrates of similar calorific value to the MCT gels. Participants visited the laboratory on three occasions (familiarisation/fitness test, pre-supplementation, post-supplementation), during which they performed a battery of cognitive tasks assessing domains such as processing speed, working memory, selective attention, decision making and coordination, before and after a prolonged bout of exercise (60 mins at 90% gas exchange threshold (GET). A 2-week supplementation period between visits 2 and 3 involved the ingestion of 2 gels per day.

RESULTS

Exercise resulted in detriments in most cognitive tasks pre-supplementation for both groups, and post-supplementation for the Placebo group (main effect ps< 0.05). Post-supplementation, the effect of exercise was mediated in the MCT group for all cognitive tasks (main effect ps< 0.05), except for the Digit and Spatial Span Backwards test phases (main effect ps> 0.05). Furthermore, MCT supplementation enhanced before-exercise cognitive performance and in some measures, such as working memory, this was maintained after-exercise (interaction effect ps> 0.05).

CONCLUSIONS

Chronic MCT supplementation enhanced before-exercise cognitive performance and offset the cognitive decline caused by a prolonged bout of exercise. In some cases, improvements in before-exercise cognitive performance were maintained after-exercise.

Lactate: A Theranostic Biomarker for Metabolic Psychiatry?

Alterations in neurometabolism and mitochondria are implicated in the pathophysiology of psychiatric conditions such as mood disorders and schizophrenia. Thus, developing objective biomarkers related to brain mitochondrial function is crucial for the development of interventions, such as central nervous system penetrating agents that target brain health. Lactate, a major circulatory fuel source that can be produced and utilized by the brain and body, is presented as a theranostic biomarker for neurometabolic dysfunction in psychiatric conditions. This concept is based on three key properties of lactate that make it an intriguing metabolic intermediate with implications for this field: Firstly, the lactate response to various stimuli, including physiological or psychological stress, represents a quantifiable and dynamic marker that reflects metabolic and mitochondrial health. Second, lactate concentration in the brain is tightly regulated according to the sleep-wake cycle, the dysregulation of which is implicated in both metabolic and mood disorders. Third, lactate universally integrates arousal behaviours, pH, cellular metabolism, redox states, oxidative stress, and inflammation, and can signal and encode this information via intra- and extracellular pathways in the brain. In this review, we expand on the above properties of lactate and discuss the methodological developments and rationale for the use of functional magnetic resonance spectroscopy for in vivo monitoring of brain lactate. We conclude that accurate and dynamic assessment of brain lactate responses might contribute to the development of novel and personalized therapies that improve mitochondrial health in psychiatric disorders and other conditions associated with neurometabolic dysfunction.

Characteristics of changes in the functional status of the brain before and after 1,000 m all-out paddling for different levels of dragon boat athletes

Purposes

Dragon boat is a traditional sport in China, but the brain function characteristics of dragon boat athletes are still unclear. Our purpose is to explore the changing characteristics of brain function of dragon boat athletes at different levels before and after exercise by monitoring the changes of EEG power spectrum and microstate of athletes before and after rowing.

Methods

Twenty-four expert dragon boat athletes and 25 novice dragon boat athletes were selected as test subjects to perform the 1,000 m all-out paddling exercise on a dragon boat dynamometer. Their resting EEG data was collected pre- and post-exercise, and the EEG data was pre-processed and then analyzed using power spectrum and microstate based on Matlab software.

Results

Post-Exercise, the Heart Rate peak (HR peak), Percentage of Heart Rate max (HR max), Rating of Perceived Exertion (RPE), and Exercise duration of the novice group were significantly higher than expert group (p < 0.01). Pre-exercise, the power spectral density values in the δ, α1, α2, and β1 bands were significantly higher in the expert group compared to the novice group (p < 0.05). Post-exercise, the power spectral density values in the δ, θ, and α1 bands were significantly lower in the expert group compared to the novice group (p < 0.05), the power spectral density values of α2, β1, and β2 bands were significantly higher (p < 0.05). The results of microstate analysis showed that the duration and contribution of microstate class D were significantly higher in the pre-exercise expert group compared to the novice group (p < 0.05), the transition probabilities of A → D, C → D, and D → A were significantly higher (p < 0.05). Post-exercise, the duration, and contribution of microstate class C in the expert group decreased significantly compared to the novice group (p < 0.05), the occurrence of microstate classes A and D were significantly higher (p < 0.05), the transition probability of A → B was significantly higher (p < 0.05), and the transition probabilities of C → D and D → C were significantly lower (p < 0.05).

Conclusion

The functional brain state of dragon boat athletes was characterized by expert athletes with closer synaptic connections of brain neurons and higher activation of the dorsal attention network in the resting state pre-exercise. There still had higher activation of cortical neurons after paddling exercise. Expert athletes can better adapt to acute full-speed oar training.

Effects of High-Intensity Interval Training Protocols on Blood Lactate Levels and Cognition in Healthy Adults: Systematic Review and Meta-Regression

BACKGROUND

Some health benefits from high-intensity interval training (HIIT) are facilitated by peripheral blood lactate levels. However, the lactate response from HIIT is variable and dependent on protocol parameters.

OBJECTIVES

We aimed to determine the HIIT protocol parameters that elicited peak lactate levels, and how these levels are associated with post-HIIT cognitive performance.

STUDY DESIGN

We conducted a systematic review with meta-regression.

METHODS

MEDLINE, Embase, CENTRAL, SPORTDiscus, and CINAHL + were searched from database inception to 8 April, 2022. Peer-reviewed primary research in healthy adults that determined lactate (mmol/L) and cognitive performance after one HIIT session was included. Mixed-effects meta-regressions determined the protocol parameters that elicited peak lactate levels, and linear regressions modelled the relationship between lactate levels and cognitive performance.

RESULTS

Study entries (n = 226) involving 2560 participants (mean age 24.1 ± 4.7 years) were included in the meta-regression. A low total work-interval volume (~ 5 min), recovery intervals that are about five times longer than work intervals, and a medium session volume (~ 15 min), elicited peak lactate levels, even when controlling for intensity, fitness (peak oxygen consumption) and blood measurement methods. Lactate levels immediately post-HIIT explained 14-17% of variance in Stroop interference condition at 30 min post-HIIT.

CONCLUSIONS

A HIIT protocol that uses the above parameters (e.g., 8 × 30-s maximal intensity with 90-s recovery) can elicit peak lactate, a molecule that is known to benefit the central nervous system and be involved in exercise training adaptations. This review reports the state of the science in regard to the lactate response following HIIT, which is relevant to those in the sports medicine field designing HIIT training programs.

TRIAL REGISTRY

Clinical Trial Registration: PROSPERO (CRD42020204400).

A Comparative Study of Inhibition Function between High-Intensity Interval Training and Moderate-Intensity Continuous Training in Healthy People: A Systematic Review with Meta-Analysis

Meta-analysis was used to compare the effects of two interventions, high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT), on inhibition in executive function in healthy people, providing some theoretical basis for exercise practice and health interventions. We searched the PubMed, Science Direct, Web Of science, Cochrane, and CNKI databases for relevant articles on the inhibition function effects of HIIT and MICT in healthy populations for the period of library construction to 15 September 2022. The basic information of the screened literature was organized and summarized using Excel. Statistical analysis of the correct rate and response time indicators of the inhibition function in the HIIT and MICT groups was performed using Review Manager 5.3 analysis software. A total of 285 subjects from 8 studies were included in this study, the number of HIIT subjects was 142, the number of MICT subjects was 143, including teenagers, young adults, and the elderly. Eight studies included response time, and four included correct rate and response time. The standardized mean difference (SMD) for correct rate inhibition function in the HIIT and MICT groups was 0.14, 95% CI (-0.18, 0.47), SMD at response time was 0.03, 95% CI (-0.20, 0.27). In addition, no significant differences were found between the two exercise modalities in either the intervention period or the population receiving the intervention. Both HIIT and MICT could improve inhibition function in healthy people, but there was no significant difference in the improvement effect between them. It is hoped that this study can provide some references for people's choice of health intervention methods and clinical practice.

Overview on brain function enhancement of Internet addicts through exercise intervention: Based on reward-execution-decision cycle

Internet addiction (IA) has become an impulse control disorder included in the category of psychiatric disorders. The IA trend significantly increased after the outbreak of the new crown epidemic. IA damages some brain functions in humans. Emerging evidence suggests that exercise exerts beneficial effects on the brain function and cognitive level damaged by IA. This work reviews the neurobiological mechanisms of IA and describes the brain function impairment by IA from three systems: reward, execution, and decision-making. Furthermore, we sort out the research related to exercise intervention on IA and its effect on improving brain function. The internal and external factors that produce IA must be considered when summarizing movement interventions from a behavioral perspective. We can design exercise prescriptions based on exercise interests and achieve the goal of quitting IA. This work explores the possible mechanisms of exercise to improve IA through systematic analysis. Furthermore, this work provides research directions for the future targeted design of exercise prescriptions.

The effects of acute high-intensity aerobic exercise on cognitive performance: A structured narrative review

It is well established that acute moderate-intensity exercise improves cognitive performance. However, the effects of acute high-intensity aerobic exercise on cognitive performance have not been well characterized. In this review, we summarize the literature investigating the exercise-cognition interaction, especially focusing on high-intensity aerobic exercise. We discuss methodological and physiological factors that potentially mediate cognitive performance in response to high-intensity exercise. We propose that the effects of high-intensity exercise on cognitive performance are primarily affected by the timing of cognitive task (during vs. after exercise, and the time delay after exercise). In particular, cognitive performance is more likely to be impaired during high-intensity exercise when both cognitive and physiological demands are high and completed simultaneously (i.e., the dual-task paradigm). The effects may also be affected by the type of cognitive task, physical fitness, exercise mode/duration, and age. Second, we suggest that interactions between changes in regional cerebral blood flow (CBF), cerebral oxygenation, cerebral metabolism, neuromodulation by neurotransmitters/neurotrophic factors, and a variety of psychological factors are promising candidates that determine cognitive performance in response to acute high-intensity exercise. The present review has implications for recreational, sporting, and occupational activities where high cognitive and physiological demands are required to be completed concurrently.

Insulin blood-brain barrier transport and interactions are greater following exercise in mice

Exercise has multiple beneficial effects including improving peripheral insulin sensitivity, improving central function such as memory, and restoring a dysregulated blood-brain barrier (BBB). Central nervous system (CNS) insulin resistance is a common feature of cognitive impairment, including Alzheimer's disease. Delivery of insulin to the brain can improve memory. Endogenous insulin must cross the BBB to directly act within the CNS and this transport system can be affected by various physiological states and serum factors. Therefore, the current study sought to investigate whether exercise could enhance insulin BBB transport as a mechanism for the underlying benefits of exercise on cognition. We investigated radioactive insulin BBB pharmacokinetics following an acute bout of exercise in young, male and female CD-1 mice. In addition, we investigated changes in serum levels of substrates that are known to affect insulin BBB transport. Finally, we measured the basal level of a downstream protein involved in insulin receptor signaling in various brain regions as well as muscle. We found insulin BBB transport in males was greater following exercise, and in males and females to both enhance the level of insulin vascular binding and alter CNS insulin receptor signaling, independent of changes in serum factors known to alter insulin BBB transport.NEW & NOTEWORTHY Central nervous system (CNS) insulin and exercise are beneficial for cognition. CNS insulin resistance is present in Alzheimer's disease. CNS insulin levels are regulated by transport across the blood-brain barrier (BBB). We show that exercise can enhance insulin BBB transport and binding of insulin to the brain's vasculature in mice. There were no changes in serum factors known to alter insulin BBB pharmacokinetics. We conclude exercise could impact cognition through regulation of insulin BBB transport.

Priming cardiovascular exercise improves complex motor skill learning by affecting the trajectory of learning-related brain plasticity

In recent years, mounting evidence from animal models and studies in humans has accumulated for the role of cardiovascular exercise (CE) in improving motor performance and learning. Both CE and motor learning may induce highly dynamic structural and functional brain changes, but how both processes interact to boost learning is presently unclear. Here, we hypothesized that subjects receiving CE would show a different pattern of learning-related brain plasticity compared to non-CE controls, which in turn associates with improved motor learning. To address this issue, we paired CE and motor learning sequentially in a randomized controlled trial with healthy human participants. Specifically, we compared the effects of a 2-week CE intervention against a non-CE control group on subsequent learning of a challenging dynamic balancing task (DBT) over 6 consecutive weeks. Structural and functional MRI measurements were conducted at regular 2-week time intervals to investigate dynamic brain changes during the experiment. The trajectory of learning-related changes in white matter microstructure beneath parieto-occipital and primary sensorimotor areas of the right hemisphere differed between the CE vs. non-CE groups, and these changes correlated with improved learning of the CE group. While group differences in sensorimotor white matter were already present immediately after CE and persisted during DBT learning, parieto-occipital effects gradually emerged during motor learning. Finally, we found that spontaneous neural activity at rest in gray matter spatially adjacent to white matter findings was also altered, therefore indicating a meaningful link between structural and functional plasticity. Collectively, these findings may lead to a better understanding of the neural mechanisms mediating the CE-learning link within the brain.

Bicarbonate supplementation via lactate efflux improves anaerobic and cognitive performance in elite combat sport athletes

The aim of this study was the assessment of sodium bicarbonate supplementation (NaHCO₃^-) on anaerobic and cognitive performance, assuming ergogenic effect of HCO₃ by improving buffering capacity and greater lactate efflux, which may have indirect effect on circulating neurotrophin level (e.g BDNF, IGF-1) and memory. Sixteen well-trained judo athletes completed a randomized trial of either a NaHCO₃^- (EG) (5000 mg x 2/day/90 min before training)or placebo for 21 days (CG). Before and after treatment, athletes completed double Wingate test (Wt) protocol following which they performed perceived Working Memory test (pWM). Results suggested significant increase in Upper Limb Total Work (with p = 0.011), Mean Power (with p = 0.001), post exercise LA concentration (from 15.51 mmol/L to 18.10 mmol/L with p = 0.01) and HCO3_rest concentrations (from 27.37 mmol/l to 28.91 mmol/l with p = 0.001), when compared to baseline values in EG. The analysis showed statistically significant increase in values for IGF-1 (with p = 0.001) and decrease for cortisol and BDNF (with p = 0.001) in EG and CG, when pre and post exercise values were compared. We also revealed statistically significant decrease in values for display time after ingestion of HCO₃ between pre and post exercise (with p = 0.002) In conclusion, the lack of a substantial relationship between exerkines (IGF-1, BDNF) and memory in the present study might suggest that exercise induced lactate levels is dominant mechanism improving working memory in well-train athletes.

Effect of Exercise on Brain Health: The Potential Role of Lactate as a Myokine

It has been well established in epidemiological studies and randomized controlled trials that habitual exercise is beneficial for brain health, such as cognition and mental health. Generally, it may be reasonable to say that the physiological benefits of acute exercise can prevent brain disorders in late life if such exercise is habitually/chronically conducted. However, the mechanisms of improvement in brain function via chronic exercise remain incompletely understood because such mechanisms are assumed to be multifactorial, such as the adaptation of repeated acute exercise. This review postulates that cerebral metabolism may be an important physiological factor that determines brain function. Among metabolites, the provision of lactate to meet elevated neural activity and regulate the cerebrovascular system and redox states in response to exercise may be responsible for exercise-enhanced brain health. Here, we summarize the current knowledge regarding the influence of exercise on brain health, particularly cognitive performance, with the underlying mechanisms by means of lactate. Regarding the influence of chronic exercise on brain function, the relevance of exercise intensity and modality, particularly high-intensity interval exercise, is acknowledged to induce “metabolic myokine” (i.e., lactate) for brain health.

Effect of 5 Years of Exercise Intervention at Different Intensities on Brain Structure in Older Adults from the General Population: A Generation 100 Substudy

Purpose

The aim was to examine the effect of a 5-year exercise intervention at different intensities on brain structure in older adults from the general population partaking in the randomized controlled trial Generation 100 Study.

Participants and Methods

Generation 100 Study participants were invited to a longitudinal neuroimaging study before randomization. A total of 105 participants (52 women, 70–77 years) volunteered. Participants were randomized into supervised exercise twice a week performing high intensity interval training in 4×4 intervals at ~90% peak heart rate (HIIT, n = 33) or 50 minutes of moderate intensity continuous training at ~70% of peak heart rate (MICT, n = 24). The control group (n = 48) followed the national physical activity guidelines of ≥30 min physical activity daily. Brain MRI at 3T, clinical and cardiorespiratory fitness (CRF), measured as peak oxygen uptake, were collected at baseline, and after 1, 3, and 5 years of intervention. Brain volumes and cortical thickness were derived from T1 weighted 3D MRI data using FreeSurfer. The effect of HIIT or MICT on brain volumes over time was investigated with linear mixed models, while linear regressions examined the effect of baseline CRF on brain volumes at later time points.

Results

Adherence in each group was between 79 and 94% after 5 years. CRF increased significantly in all groups during the first year. Compared to controls, the HIIT group had significantly increased hippocampal atrophy located to CA1 and hippocampal body, though within normal range, and the MICT group greater thalamic atrophy. No other effects of intervention group were found. CRF across the intervention was not associated with brain structure, but CRF at baseline was positively associated with cortical volume at all later time points.

Conclusion

Higher baseline CRF reduced 5-year cortical atrophy rate in older adults, while following physical activity guidelines was associated with the lowest hippocampal and thalamic atrophy rates.

Lactate as Potential Mediators for Exercise-Induced Positive Effects on Neuroplasticity and Cerebrovascular Plasticity

The accumulated evidence from animal and human studies supports that exercise is beneficial to physical health. Exercise can upregulate various neurotrophic factors, activate neuroplasticity, and play a positive role in improving and enhancing cerebrovascular function. Due to its economy, convenience, and ability to prevent or ameliorate various aging-related diseases, exercise, a healthy lifestyle, is increasingly popularized by people. However, the mechanism by which exercise performs this function and how it is transmitted from muscles to the brain remains incompletely understood. Here, we review the beneficial effects of exercise with different intensities on the brain with a focus on the positive effects of lactate on neuroplasticity and cerebrovascular plasticity. Based on these recent studies, we propose that lactate, a waste previously misunderstood as a by-product of glycolysis in the past, may be a key signal molecule that regulates the beneficial adaptation of the brain caused by exercise. Importantly, we speculate that a central protective mechanism may underlie the cognitive benefits induced by exercise.

Rationale and methods to characterize the acute exercise response in aging and Alzheimer's Disease: the AEROBIC pilot study

There is evidence that exercise benefits the brain, but the mechanisms for this benefit are unclear. The chronic benefits of exercise are likely a product of discreet, acute responses in exercise-related blood biomarkers and brain metabolism. This acute exercise response has not been compared in aging and Alzheimer's Disease (AD). It is known that acute exercise elicits a powerful peripheral response in young individuals, and exercise-related biomarkers such as glucose and lactate readily penetrate the brain. How this changes with aging and neurodegenerative disease is less clear. It is critical to characterize and understand the acute effects of exercise, including different exercise intensities, in terms of the peripheral metabolic response and relationship with brain metabolism. This will help determine potential mechanisms for brain benefits of exercise and better inform the design of future clinical trials. The primary goal of the AEROBIC study is to characterize the acute exercise response of brain glucose metabolism and exercise-related blood biomarkers. We will measure how cerebral metabolism is affected by an acute bout of moderate and higher intensity exercise and characterize the extent to which this differs between cognitively healthy older adults and individuals with AD. Related to this primary goal, we will quantify the peripheral biomarker response to moderate and higher intensity exercise and how this relates to brain metabolic change in both groups.

18F-FDG cerebellum/liver index as a prognostic factor for progression-free survival in diffuse large B-cell lymphoma

OBJECTIVE

18F-FDG PET/CT provides valuable informations regarding the prognosis of DLBCL. The aim of this study is to test a novel index based on cerebellar uptake to predict progression free survival in DLBCL patients.

METHODS

Data from patients with de novo DLBCL between January 2011 and December 2018 were retrospectively collected and PFS was determined. The conventional PET parameters (SUV_max and total metabolic tumor volume) and the CLIP, corresponding to the ratio of the cerebellum SUV_max over the liver SUV_mean, were extracted from baseline 18F-FDG PET.

RESULTS

Ninety-five patients were included. When using a threshold of 3.24, CLIP was a significant predictor of PFS on univariate analysis (HR 3.4, p < 0.001) with different 5-year survival rates: 68% (CLIP ≥ 3.24) versus 32% (CLIP < 3.24). Multivariate analysis confirmed the prognostic value of CLIP, as it is one of the two factors remaining significant with β2-microglobulin (HR 2.1 and 2.5 respectively, p = 0.04 and p = 0.03). A score associating β2-microglobulin and CLIP allowed to separate the population into three groups of different outcome in terms of 5-year PFS: low risk (80%), intermediate risk (42%) and high risk (17%).

CONCLUSIONS

The CLIP derived from pre-therapeutic 18F-FDG PET seems to be an interesting predictive marker of PFS in DLBCL treated by immunochemotherapy.

A reduced physiological 18F-fluorodeoxyglucose uptake in the brain and liver caused by malignant lymphoma being deprived of the tracer

Purpose : To investigate whether or not the physiological brain and liver FDG uptake are decreased in patients with highly accelerated glycolysis lesions. Methods : We retrospectively analyzed 51 patients with malignant lymphoma. We compared the FDG uptake in the brain and liver of the patients with that in a control group. In 24 patients with a complete response (CR) or partial response (PR) to treatment, we compared the brain and liver uptake before and after treatment. Results : The maximum standardized uptake value (SUVmax) and total glycolytic volume (TGV) of the brain as well as the SUVmax and mean standardized uptake value (SUVmean) of the liver in malignant lymphoma patients were 13.1 ± 2.3, 7386.3 ± 1918.4, 3.2 ± 0.5, and 2.3 ± 0.4, respectively ; in the control group, these values were 14.9 ± 2.4, 8566.2 ± 1659.5, 3.4 ± 0.4, and 2.5 ± 0.3, respectively. The SUVmax and TGV of the brain and the SUVmean of the liver in malignant lymphoma patients were significantly lower than the control group. The SUVmax and TGV of the brain after treatment were significantly higher than before treatment. Both the SUVmax and SUVmean of liver after treatment were higher than before treatment, but not significant. Conclusion : A decreased physiological brain and liver FDG uptake is caused by highly accelerated lesion glycolysis. J. Med. Invest. 68 : 181-185, February, 2021.

Sustained Effects of High-Intensity Interval Exercise and Moderate-Intensity Continuous Exercise on Inhibitory Control

This study examined the immediate and sustained effects of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) bouts on inhibitory control in young adults. Participants (n = 41) engaged in (1) a session of HIIE, involving 10 one-minute runs on a treadmill at an intensity targeting 85–90% HR_max interspersed with self-paced walking at 60% HR_max; (2) a session of MICE, involving a 20 min run on a treadmill at an intensity of 60–70% HR_max; and (3) a control session, involving 24 min of resting on separate days in a counterbalanced order. Using a flanker task, inhibitory control was assessed before the intervention (t₀), immediately after the session (t₁), and then at 30 min (t₂), 60 min (t₃), and 90 min (t₄) after the session. During the flanker task, the response time (RT) for incongruent trials immediately after HIIE was significantly shortened compared to that before exercise. This shortened RT was sustained for 90 min post-exercise during recovery from HIIE. Interference scores of RT were also reduced after HIIE, benefitting inhibitory control, and were maintained for 90 min post-exercise. Reduced accuracy interference scores were recorded following HIIE compared to the control session. Improvements in inhibitory control elicited by HIIE were sustained for at least 90 min post-exercise. In contrast, an improvement in inhibitory control was not observed during the MICE session. HIIE might represent a time-efficient approach for enhancing inhibitory control.

Lactate consumption mediates repeated high-intensity interval exercise-enhanced executive function in adult males

[Purpose]

Lactate is a principal energy substrate for the brain during exercise. A single bout of high-intensity interval exercise (HIIE) can increase the blood lactate level, brain lactate uptake, and executive function (EF). However, repeated HIIE can attenuate exercise-induced increases in lactate level and EF. The lactate levels in the brain and blood are reported to be correlated with exercise-enhanced EF. However, research is yet to explain the cause-and-effect relationship between lactate and EF. This study examined whether lactate consumption improves the attenuated exerciseenhanced EF caused by repeated HIIE.

[Methods]

Eleven healthy men performed two sets of HIIE, and after each set, 30 min were given for rest and examination. In the 2^nd set, the subjects consumed experimental beverages containing (n = 6) and not containing (n = 5) lactate. Blood, cardiovascular, and psychological variables were measured, and EF was evaluated by the computerized color–word Stroop test.

[Results]

The lactate group had a higher EF (P < 0.05) and tended to have a higher blood lactate level (P = 0.082) than the control group in the 2^nd set of HIIE. Moreover, blood lactate concentration was correlated with the interference score (i.e., reverse score of EF) (r = -0.394; P < 0.05).

[Conclusion]

Our results suggest that the attenuated exercise-enhanced EF after repeated HIIE can be improved through lactate consumption. However, the role of lactate needs to be elucidated in future studies, as it can be used for improving athletes’ performance and also in cognitive decline-related clinical studies.

Potential Roles of Exercise-Induced Plasma Metabolites Linking Exercise to Health Benefits

Regular exercise has a myriad of health benefits. An increase in circulating exercise factors following exercise is a critical physiological response. Numerous studies have shown that exercise factors released from tissues during physical activity may contribute to health benefits via autocrine, paracrine, and endocrine mechanisms. Myokines, classified as proteins secreted from skeletal muscle, are representative exercise factors. The roles of myokines have been demonstrated in a variety of exercise-related functions linked to health benefits. In addition to myokines, metabolites are also exercise factors. Exercise changes the levels of various metabolites via metabolic reactions. Several studies have identified exercise-induced metabolites that positively influence organ functions. Here, we provide an overview of selected metabolites secreted into the circulation upon exercise.

Metformin May Contribute to Inter-individual Variability for Glycemic Responses to Exercise

Metformin and exercise independently improve glycemic control. Metformin traditionally is considered to reduce hepatic glucose production, while exercise training is thought to stimulate skeletal muscle glucose disposal. Collectively, combining treatments would lead to the anticipation for additive glucose regulatory effects. Herein, we discuss recent literature suggesting that metformin may inhibit, enhance or have no effect on exercise mediated benefits toward glucose regulation, with particular emphasis on insulin sensitivity. Importantly, we address issues surrounding the impact of metformin on exercise induced glycemic benefit across multiple insulin sensitive tissues (e.g., skeletal muscle, liver, adipose, vasculature, and the brain) in effort to illuminate potential sources of inter-individual glycemic variation. Therefore, the review identifies gaps in knowledge that require attention in order to optimize medical approaches that improve care of people with elevated blood glucose levels and are at risk of cardiovascular disease.

Physical and Cognitive Performance During Upper-Extremity Versus Full-Body Exercise Under Dual Tasking Conditions

The purpose of this study was to investigate physical and cognitive performance during dual task conditions of upper-extremity (UE) or full-body (FB) rowing exercise. In a crossover counterbalanced design, college-aged male and female participants completed five conditions: (a) Sitting, (b) Single task UE rowing, (c) Single task FB rowing, (d) Dual task UE rowing, and (e) Dual task FB rowing. For single task UE and FB rowing conditions, participants were asked to row as hard as possible. After sitting and dual-task conditions, we administered the Paced Auditory Serial Addition Test (PASAT) and a word-list memory test. We analyzed participants' absolute differences (single task - dual task) in power output and their cognitive test scores to compare UE and FB rowing. There were no significant absolute differences from sitting to dual task conditions of UE and FB rowing for either PASAT (p = 0.958) or word list memory (p = 0.899) cognitive scores. Absolute power output loss from single to dual task conditions was significantly higher in FB versus UE for PASAT (p = 0.039; d = 0.54) and word list memory (p = 0.021; d = 0.66) in the dual task condition. These results suggest that, while cognitive performance was preserved regardless of the amount of muscle mass activated during dual task rowing, physical performance suffered more during FB than UE rowing under the dual task condition. These findings have important implications for optimizing cognitive and physical performance in dual task situations.

Plasma Concentration of Irisin and Brain-Derived-Neurotrophic Factor and Their Association With the Level of Erythrocyte Adenine Nucleotides in Response to Long-Term Endurance Training at Rest and After a Single Bout of Exercise

The study aimed to assess the effect of a single bout of incremental exercise on irisin and BDNF plasma concentrations as related to erythrocyte purine nucleotides concentration at rest and after exercise. Master endurance master athletes (training experience 38 ± 6 years) and a group of untrained participants completed a single bout of progressive incremental exercise test until exhaustion. The dual-energy x-ray absorptiometry and blood collection were performed. Blood was taken twice at rest and 10 min after exercise. Concentrations of ATP, ADP, and AMP were assessed in the erythrocytes. Hypoxanthine and uric acid were determined in plasma using the high-performance liquid chromatography. Plasma concentrations of irisin and BDNF were assessed through the immunoenzymatic method. The ATP level, ATP/ADP ratio and AEC value were significantly higher in the athletic group. A significantly higher concentration of BDNF was it also noted in the trained group that correlated with the erythrocyte energy status at rest. The single session of exercise induced a significant increase in ATP erythrocyte levels in both groups. Both exerkines significantly correlated at rest with red blood cell adenine nucleotides and degradation products (BDNF positively and irisin negatively). The blood concentration of BDNF and irisin, in response to exercise, was not significantly different between groups. Obtained data revealed a higher erythrocyte energy status and lower purine degradation products concentration in master athletes. Also resting plasma exerkines differed substantially between groups. In conclusion, long-term training resulted in exercise adaptation reflected by a higher erythrocyte energy status, lower purine degradation products concentration and modified concentration of exerkines (higher BDNF and lower irisin blood concentrations). Therefore, we consider the training-induced adaptations in master athletes to be beneficial and significant. The moderate level of physical activity in the untrained group, even if sufficient in terms of general health, did not cause any discernible changes.

Long-term Ashtanga yoga practice decreases medial temporal and brainstem glucose metabolism in relation to years of experience

Background

Yoga is increasingly popular worldwide with several physical and mental benefits, but the underlying neurobiology remains unclear. Whereas many studies have focused on pure meditational aspects, the triad of yoga includes meditation, postures, and breathing. We conducted a cross-sectional study comparing experienced yoga practitioners to yoga-naive healthy subjects using a multiparametric 2 × 2 design with simultaneous positron emission tomography/magnetic resonance (PET/MR) imaging.

Methods

¹⁸F-FDG PET, morphometric and diffusion tensor imaging, resting state fMRI, and MR spectroscopy were acquired in 10 experienced (4.8 ± 2.3 years of regular yoga experience) yoga practitioners and 15 matched controls in rest and after a single practice (yoga practice and physical exercise, respectively).

Results

In rest, decreased regional glucose metabolism in the medial temporal cortex, striatum, and brainstem was observed in yoga practitioners compared to controls (p < 0.0001), with a significant inverse correlation of resting parahippocampal and brainstem metabolism with years of regular yoga practice (ρ < − 0.63, p < 0.05). A single yoga practice resulted in significant hypermetabolism in the cerebellum (p < 0.0001). None of the MR measures differed, both at rest and after intervention.

Conclusions

Experienced yoga practitioners show regional long-term decreases in glucose metabolism related to years of practice. To elucidate a potential causality, a prospective longitudinal study in yoga-naive individuals is warranted.

Lactate and BDNF: Key Mediators of Exercise Induced Neuroplasticity?

Accumulating evidence from animal and human studies supports the notion that physical exercise can enhance neuroplasticity and thus reduce the risk of several neurodegenerative diseases (e.g., dementia). However, the underlying neurobiological mechanisms of exercise induced neuroplasticity are still largely unknown. One potential mediator of exercise effects is the neurotrophin BDNF, which enhances neuroplasticity via different pathways (e.g., synaptogenesis, neurogenesis, long-term potentiation). Current research has shown that (i) increased peripheral lactate levels (following high intensity exercise) are associated with increased peripheral BDNF levels, (ii) lactate infusion at rest can increase peripheral and central BDNF levels and (iii) lactate plays a very complex role in the brain’s metabolism. In this review, we summarize the role and relationship of lactate and BDNF in exercise induced neuroplasticity.

The Contribution of Functional Magnetic Resonance Imaging to the Understanding of the Effects of Acute Physical Exercise on Cognition

The fact that a single bout of acute physical exercise has a positive impact on cognition is well-established in the literature, but the neural correlates that underlie these cognitive improvements are not well understood. Here, the use of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), offers great potential, which is just starting to be recognized. This review aims at providing an overview of those studies that used fMRI to investigate the effects of acute physical exercises on cerebral hemodynamics and cognition. To this end, a systematic literature survey was conducted by two independent reviewers across five electronic databases. The search returned 668 studies, of which 14 studies met the inclusion criteria and were analyzed in this systematic review. Although the findings of the reviewed studies suggest that acute physical exercise (e.g., cycling) leads to profound changes in functional brain activation, the small number of available studies and the great variability in the study protocols limits the conclusions that can be drawn with certainty. In order to overcome these limitations, new, more well-designed trials are needed that (i) use a more rigorous study design, (ii) apply more sophisticated filter methods in fMRI data analysis, (iii) describe the applied processing steps of fMRI data analysis in more detail, and (iv) provide a more precise exercise prescription.

Acute Sprint Interval Exercise Increases Both Cognitive Functions and Peripheral Neurotrophic Factors in Humans: The Possible Involvement of Lactate

There is increasing attention to sprint interval exercise (SIE) training as a time-efficient exercise regime. Recent studies, including our own (Kujach et al., 2018), have shown that acute high-intensity intermittent exercise can improve cognitive function; however, the neurobiological mechanisms underlying the effect still remain unknown. We thus examined the effects of acute SIE on cognitive function by monitoring the peripheral levels of growth and neurotrophic factors as well as blood lactate (LA) as potential mechanisms. Thirty-six young males participated in the current study and were divided into two groups: SIE (n = 20; mean age: 21.0 ± 0.9 years) and resting control (CTR) (n = 16; mean age: 21.7 ± 1.3 years). The SIE session consisted of 5 min of warm-up exercise and six sets of 30 s of all-out cycling exercise followed by 4.5 min of rest on a cycling-ergometer. Blood samples to evaluate the changes of serum concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and blood LA were obtained at three time points: before, immediately after, and 60 min after each session. A Stroop task (ST) and trail making test (TMT) parts A and B were used to assess cognitive functions. Acute SIE shortened response times for both the ST and TMT A and B. Meanwhile, the peripheral levels of BDNF, IGF-1, and VEGF were significantly increased after an acute bout of SIE compared to those in CTR. In response to acute SIE, blood LA levels significantly increased and correlated with increased levels of BDNF, IGF-1, and VEGF. Furthermore, cognitive function and BDNF are found to be correlated. The current results suggest that SIE could have beneficial effects on cognitive functions with increased neuroprotective factors along with peripheral LA concentration in humans.

Dose-Response Matters! - A Perspective on the Exercise Prescription in Exercise-Cognition Research

In general, it is well recognized that both acute physical exercises and regular physical training influence brain plasticity and cognitive functions positively. However, growing evidence shows that the same physical exercises induce very heterogeneous outcomes across individuals. In an attempt to better understand this interindividual heterogeneity in response to acute and regular physical exercising, most research, so far, has focused on non-modifiable factors such as sex and different genotypes, while relatively little attention has been paid to exercise prescription as a modifiable factor. With an adapted exercise prescription, dosage can be made comparable across individuals, a procedure that is necessary to better understand the dose-response relationship in exercise-cognition research. This improved understanding of dose-response relationships could help to design more efficient physical training approaches against, for instance, cognitive decline.

The tenacious brain: How the anterior mid-cingulate contributes to achieving goals

Tenacity-persistence in the face of challenge-has received increasing attention, particularly because it contributes to better academic achievement, career opportunities and health outcomes. We review evidence from non-human primate neuroanatomy and structural and functional neuroimaging in humans suggesting that the anterior mid cingulate cortex (aMCC) is an important network hub in the brain that performs the cost/benefit computations necessary for tenacity. Specifically, we propose that its position as a structural and functional hub allows the aMCC to integrate signals from diverse brain systems to predict energy requirements that are needed for attention allocation, encoding of new information, and physical movement, all in the service of goal attainment. We review and integrate research findings from studies of attention, reward, memory, affect, multimodal sensory integration, and motor control to support this hypothesis. We close by discussing the implications of our framework for educational achievement, exercise and eating disorders, successful aging, and neuropsychiatric disorders such as depression and dementia.

Paradoxical Rise in Hypoglycemia Symptoms With Development of Hyperglycemia During High-Intensity Interval Training in Type 1 Diabetes

OBJECTIVE

To assess the reliability of self-perception of glycemia during high-intensity interval training (HIIT) in subjects with type 1 diabetes.

RESEARCH DESIGN AND METHODS

This randomized crossover study included subjects who completed four fasted HIIT sessions. Subjects answered the Edinburgh Hypoglycemia Scale, estimated their blood glucose (BG), and had plasma glucose (PG) collected throughout exercise and recovery.

RESULTS

As PG increased throughout exercise, hypoglycemia scores increased across each category: autonomic (3.1-4.4, P < 0.05), neuroglycopenic (1.5-2.4, P < 0.05), and nonspecific (1.3-1.9, P < 0.05). Subjects' estimated BG showed a negative bias that widened as exercise progressed and peaked at -1.6 ± 3.3 mmol/L (P < 0.001) postinsulin correction.

CONCLUSIONS

During HIIT, despite progressing hyperglycemia, subjects experience increased hypoglycemia symptoms and tend to underestimate their BG level.

Inter-Individual Differences in Cognitive Response to a Single Bout of Physical Exercise-A Randomized Controlled Cross-Over Study

Recent reviews have shown that acute exercise can improve cognitive functions, especially executive functions. However, a closer look at the included studies revealed a wide inter-individual variability in the effects of exercise on cognition. Therefore, thirty-nine healthy adults (age: 19–30 years) were analyzed in a randomized, controlled cross-over study with two exercise groups (n = 13 each) and a sedentary control group (n = 13). The exercise conditions included moderate (30 min at 40–59% VO_2max) and high intensity interval (five × 2 min at 90% VO_2max with 3 min active recovery at 40% VO_2max) treadmill exercise. The main outcome assessed was cognitive performance (attention, inhibitory control, cognitive flexibility) and underlying inter-individual variability in young adults. On the group level no significant group or group × time interaction effects were observed. Using a median split, we found significant differences between low and high cognitive performers regarding cognitive function following moderate and high intensity interval treadmill exercise. Furthermore, using a pre-determined threshold we could identify responders and non-responders to acute exercise. Therefore, future research should consider individual performance requirements.

A short bout of high-intensity exercise alters ipsilesional motor cortical excitability post-stroke

Background: Acute exercise can increase motor cortical excitability and enhance motor learning in healthy individuals, an effect known as exercise priming. Whether it has the same effects in people with stroke is unclear. Objectives: The objective of this study was to investigate whether a short, clinically-feasible high-intensity exercise protocol can increase motor cortical excitability in non-exercised muscles of chronic stroke survivors. Methods: Thirteen participants with chronic, unilateral stroke participated in two sessions, at least one week apart, in a crossover design. In each session, they underwent either high-intensity lower extremity exercise or quiet rest. Motor cortical excitability of the extensor carpi radialis muscles was measured bilaterally with transcranial magnetic stimulation before and immediately after either exercise or rest. Motor cortical excitability changes (post-exercise or rest measures normalized to pre-test measures) were compared between exercise vs. rest conditions. Results: All participants were able to reach the target high-intensity exercise level. Blood lactate levels increased significantly after exercise (p < .001, d = 2.85). Resting motor evoked potentials from the lesioned hemisphere increased after exercise (mean 1.66; 95% CI: 1.19, 2.13) compared to the rest condition (mean 1.23; 95% CI: 0.64, 1.82), p = .046, d = 2.76, but this was not the case for the non-lesioned hemisphere (p = .406, d = 0.25). Conclusions: High-intensity exercise can increase lesioned hemisphere motor cortical excitability in a non-exercised muscle post-stroke. Our short and clinically-advantageous exercise protocol shows promise as a potential priming method in stroke rehabilitation.

Various exercise intensities differentially regulate GAP-43 and CAP-1 expression in the rat hippocampus

Exercise intensity is known to affect neuroplasticity. Although corticosterone and lactate levels have been linked to neuroplasticity, the effect of different endurance exercise intensity-dependent production of these biochemicals on the behaviour of hippocampal growth cone markers remains incompletely explored. Here, we investigated the effects of three different endurance treadmill training episodes for six weeks on GAP-43 and CAP-1 expression in the hippocampus of adult male Wistar rats. Our findings showed that mild exercise intensity (MEI) with a lactate production slightly higher than the lactate threshold (LT) is the optimal form of physical activity for elevating GAP-43 without changing CAP-1 expression. It was further observed that high exercise intensity (HEI) with the highest level of corticosterone and lactate production, reduced GAP-43 expression, yet increased CAP-1 expression in the hippocampus. Like HEI, we further identified similar expression patterns for these markers in low exercise intensity (LEI) with blood lactate production below LT and corticosterone level similar to MEI. The findings suggested that in high-intensity exercise, the negative pattern of hippocampal neuroplasticity depends on both corticosterone and lactate levels, whereas in low-intensity exercise, the most important factor determining this negative pattern is the lactate level. Generally, MEI with a lactate production of slightly higher than LT is the most optimal intensity for improving hippocampal neuroplasticity.

Benefit effect of REM-sleep deprivation on memory impairment induced by intensive exercise in male wistar rats: with respect to hippocampal BDNF and TrkB

BACKGROUND

Many factors affect our learning and memory quality, but according to different studies, having a positive or negative impact pertains to their characteristics like intensity or the amount.

PURPOSE

The present study was conducted to investigate the effect of 24-hour REM-sleep deprivation on continuous-high intensity forced exercise-induced memory impairment and its effect on Brain-Derived Neurotrophic Factor (BDNF) and Tyrosine kinase B (TrkB) levels in the hippocampus and Prefrontal Cortex area (PFC).

MATERIAL AND METHODS

Animals were conditioned to run on treadmills for 5 weeks then, were deprived of sleep for 24 h using the modified multiple platforms. The effect of intensive exercise and/or 24-h REM-SD was studied on behavioral performance using Morris Water Maze protocol for 2 days, and BDNF/TrkB levels were assessed in hippocampus and PFC after behavioral probe test using western blotting.

RESULTS

After 5 weeks of intensive exercise and 24-h REM-SD, spatial memory impairment and reduction of BDNF and TrkB levels were found in hippocampus and PFC. 24-h REM-SD improved memory impairment and intensive exercise-induced downregulation of BDNF and TrkB protein levels.

CONCLUSION

The results of the study suggested that sleep deprivation might act as a compensatory factor to reduce memory impairment when the animal is under severe stressful condition.

A Single Bout of Aerobic Exercise Improves Motor Skill Consolidation in Parkinson's Disease

Background: Motor learning is impaired in Parkinson’s disease (PD), with patients demonstrating deficits in skill acquisition (online learning) and consolidation (offline learning) compared to healthy adults of similar age. Recent studies in young adults suggest that single bouts of aerobic exercise (AEX), performed in close temporal proximity to practicing a new motor task, may facilitate motor skill learning. Thus, we aimed at investigating the effects of a single bout of aerobic cycling on online and offline learning in PD patients.

Methods: 17 PD patients (Hoehn and Yahr 1 – 2.5, age: 64.4 ± 6.2) participated in this crossover study. Immediately prior to practicing a novel balance task, patients either performed 30 min of (i) moderate intensity (60–70% VO_2max) aerobic cycling, or (ii) seated rest (order counterbalanced). The task required patients to stabilize a balance platform (stabilometer) in a horizontal position for 30 s. For each experimental condition, patients performed 15 acquisition trials, followed by a retention test 24 h later. We calculated time in balance (platform within ± 5° from horizontal) for each trial, and analyzed within- and between-subjects differences in skill acquisition (online learning) and skill retention (offline learning) using mixed repeated-measures ANOVA.

Results: We found that the exercise bout had no effect on performance level or online gains during acquisition, despite affecting the time course of skill improvements (larger initial and reduced late skill gains). Aerobic cycling significantly improved offline learning, as reflected by larger 24-h skill retention compared to the rest condition.

Conclusion: Our results suggest that a single bout of moderate-intensity AEX is effective in improving motor skill consolidation in PD patients. Thus, acute exercise may represent an effective strategy to enhance motor memory formation in this population. More work is necessary to understand the underlying mechanisms, the optimal scheduling of exercise, and the applicability to other motor tasks. Further, the potential for patients in later disease stages need to be investigated. The study was a priori registered at ClinicalTrials.gov (NCT03245216).

Beneficial Effects of Whole Body Vibration on Brain Functions in Mice and Humans

The biological consequences of mechanical whole body vibration (WBV) on the brain are not well documented. The aim of the current study was to further investigate the effects of a 5-week WBV intervention on brain functions. Mice (C57Bl/6J males, age 15 weeks) were exposed to 30 Hz WBV sessions (10 minutes per day, 5 days per week, for a period of 5 weeks; n = 10). Controls received the same intervention without the actual vibration (n = 10). Humans (both genders, age ranging from 44-99 years) were also exposed to daily sessions of 30 Hz WBV (4 minutes per day, 4 days per week, for a period of 5 weeks; n = 18). Controls received the same protocol using a 1 Hz protocol (n = 16). Positron emission tomography imaging was performed in the mice, and revealed that glucose uptake was not changed as a consequence of the 5-week WBV intervention. Whole body vibration did, however, improve motor performance and reduced arousal-induced home cage activity. Cognitive tests in humans revealed a selective improvement in the Stroop Color-Word test. Taken together, it is concluded that WBV is a safe intervention to improve brain functioning, although the subtle effects suggest that the protocol is as yet suboptimal.

Short-term interval training alters brain glucose metabolism in subjects with insulin resistance

Brain insulin-stimulated glucose uptake (GU) is increased in obese and insulin resistant subjects but normalizes after weight loss along with improved whole-body insulin sensitivity. Our aim was to study whether short-term exercise training (moderate intensity continuous training (MICT) or sprint interval training (SIT)) alters substrates for brain energy metabolism in insulin resistance. Sedentary subjects ( n = 21, BMI 23.7-34.3 kg/m², age 43-55 y) with insulin resistance were randomized into MICT ( n = 11, intensity≥60% of VO_2peak) or SIT ( n = 10, all-out) groups for a two-week training intervention. Brain GU during insulin stimulation and fasting brain free fatty acid uptake (FAU) was measured using PET. At baseline, brain GU was positively associated with the fasting insulin level and negatively with the whole-body insulin sensitivity. The whole-body insulin sensitivity improved with both training modes (20%, p = 0.007), while only SIT led to an increase in aerobic capacity (5%, p = 0.03). SIT also reduced insulin-stimulated brain GU both in global cortical grey matter uptake (12%, p = 0.03) and in specific regions ( p < 0.05, all areas except the occipital cortex), whereas no changes were observed after MICT. Brain FAU remained unchanged after the training in both groups. These findings show that short-term SIT effectively decreases insulin-stimulated brain GU in sedentary subjects with insulin resistance.

Motivation in the Service of Allostasis: The Role of anterior Mid Cingulate Cortex

In this article, we suggest that motivation serves to anticipate the energy of the body and meet those needs before they arise, called allostasis. We describe motivation as the output of energy computations that include estimates about future energy/metabolic needs and the value of effort required for potential behaviors (i.e., whether the cost of effort is worthwhile). We bring neuroscience evidence to bear to support this hypothesis. We outline a system of brain networks that have been shown to be important for motivation, and focus in on one hub in this network, the anterior mid-cingulate cortex (aMCC), and discuss its importance for establishing motivation in the service of allostasis. We present evidence that the aMCC, positioned at the intersection of multiple brain networks, is wired to integrate signals relating to allostasis with its sensory consequences, termed interoception, as well as with cognitive control processes, sensory and motor functions. This integration guides the nervous system towards the optimal effort required to achieve a desired goal. Across a variety of task domains, we discuss the role of aMCC in motivation, including a) processing of the value of prior and expected rewards, b) assessment of energetic costs in the brain and the body, c) selectively learning and encoding prediction errors (unexpected changes) that are relevant for allostasis, d) computations for monitoring of internal states of the body and e) modulating the internal state of the body to prepare for action. Finally, we discuss the link between individual differences in aMCC processing and variation in two extreme ends of the range of motivational states, tenacity and apathy.

Self-selected music-induced reduction of perceived exertion during moderate-intensity exercise does not interfere with post-exercise improvements in inhibitory control

Acute aerobic exercise improves inhibitory control (IC). This improvement is often associated with increases in perceived exertion during exercise. However, listening to music during aerobic exercise mitigates an exercise-induced increase in perceived exertion. Thus, it is hypothesized that such effects of music may interfere with exercise-induced improvements in IC. To test this hypothesis, we examined the effect of music on post-exercise IC improvements that were induced by moderate-intensity exercise. Fifteen healthy young men performed cycle ergometer exercise with music or non-music. The exercise was performed using a moderate-intensity of 60% of VO_{2 peak} for 30 min. The music condition was performed while listening to self-selected music. The non-music condition involved no music. To evaluate IC, the Stroop task was administered before exercise, immediately after exercise, and during the 30-min post-exercise recovery period. The rate of perceived exertion immediately before moderate-intensity exercise completed was significantly lower in music condition than in non-music condition. The IC significantly improved immediately after exercise and during the post-exercise recovery period compared to before exercise in both music and non-music conditions. The post-exercise IC improvements did not significantly differ between the two conditions. These findings indicate that self-selected music-induced mitigation of the increase in perceived exertion during moderate-intensity exercise dose not interfere with exercise-induced improvements in IC. Therefore, we suggest that listening to music may be a beneficial strategy in mitigating the increase in perceived exertion during aerobic exercise without decreasing the positive effects on IC.

Moderate Physical Activity is Associated with Cerebral Glucose Metabolism in Adults at Risk for Alzheimer's Disease

The objective of this study was to investigate the relationship between accelerometer-measured physical activity (PA) and glucose metabolism in asymptomatic late-middle-aged adults. Ninety-three cognitively healthy late-middle-aged adults from the Wisconsin Registry for Alzheimer's Prevention participated in this cross-sectional study. They underwent 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and wore an accelerometer (ActiGraph GT3X+) to measure free-living PA. Accelerometer data yielded measures of light (LPA), moderate (MPA), and vigorous (VPA) intensity PA. FDG-PET images were scaled to the cerebellum and pons, and cerebral glucose metabolic rate was extracted from specific regions of interest (ROIs) known to be hypometabolic in AD, i.e., hippocampus, posterior cingulate, inferior temporal cortex, and angular gyrus. Regression analyses were utilized to examine the association between PA and glucose metabolism, while adjusting for potential confounds. There were associations between MPA and glucose metabolism in all ROIs examined. In contrast, LPA was not associated with glucose uptake in any ROI and VPA was only associated with hippocampal FDG uptake. Secondary analyses did not reveal associations between sedentary time and glucose metabolism in any of the ROIs. Exploratory voxel-wise analysis identified additional regions where MPA was significantly associated with glucose metabolism including the precuneus, supramarginal gyrus, amygdala, and middle frontal gyrus. These findings suggest that the intensity of PA is an important contributor to neuronal function in a late-middle-aged cohort, with MPA being the most salient. Prospective studies are necessary for fully elucidating the link between midlife engagement in PA and later life development of AD.

Aerobic training modulates salience network and default mode network metabolism in subjects with mild cognitive impairment

Aerobic training (AT) is a promising intervention to improve cognitive functioning. However, its modulatory effects on brain networks are not yet entirely understood. Sixty-five subjects with mild cognitive impairment performed a moderate intensity, 24-week AT program. Differences in resting regional brain glucose metabolism (rBGM) with FDG-PET were assessed before and after AT on a voxel-by-voxel basis. Structural equation modeling was used to create latent variables based on regions with significant rBGM changes and to test a hypothetical model about the inter-relationships between these changes. There were significant rBGM reductions in both anterior temporal lobes (ATL), left inferior frontal gyrus, left anterior cingulate cortex, right hippocampus, left meddle frontal gyrus and bilateral caudate nuclei. In contrast, there was an increase in rBGM in the right precuneus and left inferior frontal gyrus. Latent variables reflecting the salience network and ATL were created, while the precuneus represented the default mode network. In the model, salience network rBGM was decreased after AT. In contrast, rBGM in the default mode network increased as a final outcome. This result suggested improved salience network efficacy and increased control over other brain functional networks. The ATL network decreased its rBGM and connected to the salience network and default mode network with positive and negative correlations, respectively. The model fit values reached statistical significance, demonstrating that this model explained the variance in the measured data. In mild cognitive impairment subjects, AT modulated rBGM in salience network and default mode network nodes. Such changes were in the direction of the normally expected resting-state metabolic patterns of these networks.

Lactate in the brain: from metabolic end-product to signalling molecule

Lactate in the brain has long been associated with ischaemia; however, more recent evidence shows that it can be found there under physiological conditions. In the brain, lactate is formed predominantly in astrocytes from glucose or glycogen in response to neuronal activity signals. Thus, neurons and astrocytes show tight metabolic coupling. Lactate is transferred from astrocytes to neurons to match the neuronal energetic needs, and to provide signals that modulate neuronal functions, including excitability, plasticity and memory consolidation. In addition, lactate affects several homeostatic functions. Overall, lactate ensures adequate energy supply, modulates neuronal excitability levels and regulates adaptive functions in order to set the 'homeostatic tone' of the nervous system.

Increased Brain Glucose Uptake After 12 Weeks of Aerobic High-Intensity Interval Training in Young and Older Adults

CONTEXT

Aerobic exercise training can increase brain volume and blood flow, but the impact on brain metabolism is less known.

OBJECTIVE

We determined whether high-intensity interval training (HIIT) increases brain metabolism by measuring brain glucose uptake in younger and older adults.

DESIGN

Brain glucose uptake was measured before and after HIIT or a sedentary (SED) control period within a larger exercise study.

SETTING

Study procedures were performed at the Mayo Clinic in Rochester, MN.

PARTICIPANTS

Participants were younger (18 to 30 years) or older (65 to 80 years) SED adults who were free of major medical conditions. Group sizes were 15 for HIIT (nine younger and six older) and 12 for SED (six younger and six older).

INTERVENTION

Participants completed 12 weeks of HIIT or SED. HIIT was 3 days per week of 4 × 4 minute intervals at over 90% of peak aerobic capacity (VO2peak) with 2 days per week of treadmill walking at 70% VO2peak.

MAIN OUTCOME MEASURES

Resting brain glucose uptake was measured using 18F-fluorodeoxyglucose positron emission tomography scans at baseline and at week 12. Scans were performed at 96 hours after exercise. VO2peak was measured by indirect calorimetry.

RESULTS

Glucose uptake increased significantly in the parietal-temporal and caudate regions after HIIT compared with SED. The gains with HIIT were not observed in all brain regions. VO2peak was increased for all participants after HIIT and did not change with SED.

CONCLUSION

We demonstrate that brain glucose metabolism increased after 12 weeks of HIIT in adults in regions where it is reduced in Alzheimer's disease.

GABA concentration in sensorimotor cortex following high-intensity exercise and relationship to lactate levels

KEY POINTS

Magnetic resonance spectroscopy was conducted before and after high-intensity interval exercise. Sensorimotor cortex GABA concentration increased by 20%. The increase was positively correlated with the increase in blood lactate. There was no change in dorsolateral prefrontal cortex. There were no changes in the glutamate-glutamine-glutathione peak.

ABSTRACT

High-intensity exercise increases the concentration of circulating lactate. Cortical uptake of blood borne lactate increases during and after exercise; however, the potential relationship with changes in the concentration of neurometabolites remains unclear. Although changes in neurometabolite concentration have previously been demonstrated in primary visual cortex after exercise, it remains unknown whether these changes extend to regions such as the sensorimotor cortex (SM) or executive regions such as the dorsolateral prefrontal cortex (DLPFC). In the present study, we explored the acute after-effects of high-intensity interval training (HIIT) on the concentration of gamma-Aminobutyric acid (GABA) and the combined glutamate-glutamine-glutathione (Glx) spectral peak in the SM and DLPFC, as well as the relationship with blood lactate levels. Following HIIT, there was a robust increase in GABA concentration in the SM, as evident across the majority of participants. This change was not observed in the DLPFC. Furthermore, the increase in SM GABA was positively correlated with an increase in blood lactate. There were no changes in Glx concentration in either region. The observed increase in SM GABA concentration implies functional relevance, whereas the correlation with lactate levels may relate to the metabolic fate of exercise-derived lactate that crosses the blood-brain barrier.

Mouth rinsing with a carbohydrate solution attenuates exercise-induced decline in executive function

Background

A decline in executive function could have a negative influence on the control of actions in dynamic situations, such as sports activities. Mouth rinsing with a carbohydrate solution could serve as an effective treatment for preserving the executive function in exercise. The purpose of this study was to examine the effects of mouth rinsing with a carbohydrate solution on executive function after sustained moderately high-intensity exercise.

Methods

Eight young healthy participants completed 65 min of running at 75% V̇O₂max with two mouth-rinsing conditions: with a carbohydrate solution (CHO) or with water (CON). Executive function was assessed before and after exercise by using the incongruent task of the Stroop Color and Word Test. The levels of blood glucose; and plasma adrenocorticotropic hormone (ACTH), epinephrine, and norepinephrine (NE) were evaluated. A two-way repeated-measures ANOVA, with condition (CHO and CON) and time (pre-exercise and post-exercise) as factors, was used to examine the main and interaction effects on the outcome measures.

Results

The reaction time in the incongruent condition of the Stroop test significantly increased after exercise in CON (pre-exercise 529 ± 45 ms vs. post-exercise 547 ± 60 ms, P = 0.029) but not in CHO (pre-exercise 531 ± 54 ms vs. post-exercise 522 ± 80 ms), which resulted in a significant interaction (condition × time) on the reaction time (P = 0.028). The increased reaction time in CON indicates a decline in the executive function, which was attenuated in CHO. Increases in plasma epinephrine and NE levels demonstrated a trend toward attenuation accompanying CHO (P < 0.085), which appeared to be associated with the preservation of executive function. The blood glucose concentration showed neither significant interactions nor main effects of condition.

Conclusions

These findings indicate that mouth rinsing with a carbohydrate solution attenuated the decline in executive function induced by sustained moderately high-intensity exercise, and that such attenuation seems to be unrelated to carbohydrate metabolic pathway but rather attributed, in part, to the inhibition of the excessive release of stress hormones.