Reappraisal of the acute, moderate intensity exercise-catecholamines interaction effect on speed of cognition: role of the vagal/NTS afferent pathway

Effects of resistance exercises on inhibitory control and plasma epinephrine levels: A registered report of a crossover randomized controlled trial

According to the locus coeruleus-norepinephrine (LC-NE) theory, activity of the LC, the major releaser of NE in the brain, regulates inhibitory control. As there is reciprocal communication between circulating epinephrine and the LC, plasma epinephrine is used as the index of LC-NE activity. The aim of this crossover randomized controlled trial is to expand on previous findings by investigating the effects of free-weight, multiple-joint, and structural barbell resistance exercises. Previous studies have had some methodological limitations, such as failure to report the process of randomization, absence of resistance exercise familiarization before the maximal strength testing, and lack of protocol publication. To address these issues, this study incorporates resistance exercise familiarization, transparent reporting of randomization, and submission as a registered report. The results suggest that a single session of resistance exercise (barbell squat, press, and deadlift) with an intensity of 65%-78% 1RM for five repetitions (70%-90% relative intensity) and three sets with 3-min rest intervals improved Stroop congruent reaction time (RT) only (t(27) = -2.663, mean reduction = -15 ms, p = .013, 95% CI [-26, -3]). No significant enhancements were observed in Stroop incongruent RT, inhibitory control as indexed by Stroop effect, or inhibitory control as indexed by the RT difference between the Stroop task and the simple reaction task. Moreover, the alterations in plasma epinephrine levels did not significantly associate with changes in any measure of cognitive performance.

Effects of exercise or tai chi on Internet addiction in college students and the potential role of gut microbiota: A randomized controlled trial

OBJECTIVE

This study aimed to explore the effect of exercise or tai chi on Internet addiction disorder (IAD) among college students and clarified the abundance and population changes of gut microbiota in different groups. Thus explore the potential role of gut microbiota between exercise and IAD.

METHODS

A total of 93 subjects diagnosed with mild IAD were randomly assigned to the exercise group, the tai chi group, and the control group. The intervention groups received exercise or tai chi for 8 weeks and the control group was evaluated without any intervention. Fecal samples were collected after the intervention.

RESULTS

1) Analysis found a significant intervention effect with the exercise group showing an average decrease of 8.84 points on the Internet addiction test (IAT) compared with the control group (95%CI -15.41 to-2.27, P = 0.004). But there was no significant difference between the control group and the tai chi group. 2) Both exercise (P = 0.018) and tai chi (P = 0.026) could significantly relieve fatigue symptoms. 3) The relative abundance of the Betaproteobacteria, Porphyromonadaceae, Sutterellaceae, and Alistipes were significantly decreased in the exercise group compared with the control group, and the relative abundance of Escherichia was significantly increased in the exercise group. 4) The relative abundance of Betaproteobacteria, Sutterellaceae, and Escherichia had significant differences between the improved group and the no-improved group.

CONCLUSION

Exercise intervention has a considerable effect on treating IAD. Exercise and tai chi might have effectiveness in relieving the symptoms of fatigue. Exercise intervention regulates the gut microflora and changes the abundance of microflora to improve IAD.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT05529368.

The effect of acute exercise on cognitive and motor inhibition - Does fitness moderate this effect?

BACKGROUND

Given the extensive evidence on improvements in cognitive inhibition immediately following exercise, and the literature indicating that cognitive and motor inhibitory functions are mediated by overlapping brain networks, the aim of this study was to assess, for the first time, the effect of moderate intensity acute aerobic exercise on multi-limb motor inhibition, as compared to cognitive inhibition.

METHOD

Participants were 36 healthy adults aged 40-60 years old (mean age 46.8 ± 5.7), who were randomly assigned to experimental or control groups. One-to-two weeks following baseline assessment, participants were asked to perform a three-limb (3-Limb) inhibition task and a vocal version of the Stroop before and after either acute moderate-intense aerobic exercise (experimental group) or rest (control).

RESULTS

Similar rates of improvement were observed among both groups from baseline to the pre-test. Conversely, a meaningful, yet non-significant trend was seen among the experimental group in their pretest to posttest improvement in both cognitive and motor tasks. In addition, exploratory analysis revealed significant group differences in favor of the experimental group among highly fit participants on the 3-Limb task. A significant correlation was indicated between the inhibition conditions, i.e., choice in the motor inhibition and color/word (incongruent) in the cognitive inhibition, especially in the improvement observed following the exercise.

DISCUSSION

Moderate-intensity acute aerobic exercise is a potential stimulator of both multi-limb motor inhibition and cognitive inhibition. It appears that high-fit participants benefit from exercise more than low-fit people. Additionally, performance on behavioral tasks that represent motor and cognitive inhibition is related. This observation suggests that fitness levels and acute exercise contribute to the coupling between cognitive and motor inhibition. Neuroimaging methods would allow examining brain-behavior associations of exercise-induced changes in the brain.

Effects of a Randomised Trial of 5-Week Heart Rate Variability Biofeedback Intervention on Cognitive Function: Possible Benefits for Inhibitory Control

Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Interrelationships between exercise, functional connectivity, and cognition among healthy adults: A systematic review

The main purpose of this systematic review was to examine past literature focusing on the potential relationship between exercise (or physical activity or cardiorespiratory fitness [CRF]) and functional brain connectivity in healthy adults. Among the studies meeting this purpose, we also evaluated studies investigating whether, and how, functional connectivity may influence the exercise-cognition relationship. A systematic review was employed through several electronic databases (PsychInfo, PubMed, and Google Scholar) in accordance with PRISMA guidelines. The literature search identified 656 records, and a total of 12 studies met the inclusion criteria. Among these 12 studies, there were 4, 7, and 1 study, respectively, examining the relationship between exercise and frontal lobe connectivity, temporal lobe connectivity, and whole-brain connectivity. Also, 7 studies examined the relationship between functional connectivity and cognitive performance across multiple brain regions as a function of exercise. Existing literature suggests that CRF, habitual physical activity, and varying intensities of acute exercise can strengthen functional connections among a wide variety of regions and subcortical structures of the human brain. These exercise-induced functional connectivity changes within and between specific brain structures/networks supporting cognitive processing may improve various domains of cognitive function. Given these complex associations, a thorough understanding of how functional connectivity plays a mediating role in the exercise-cognition interaction is needed in future studies.

Hippocampal Blood Flow Is Increased After 20 min of Moderate-Intensity Exercise

Long-term exercise interventions have been shown to be a potent trigger for both neurogenesis and vascular plasticity. However, little is known about the underlying temporal dynamics and specifically when exercise-induced vascular adaptations first occur, which is vital for therapeutic applications. In this study, we investigated whether a single session of moderate-intensity exercise was sufficient to induce changes in the cerebral vasculature. We employed arterial spin labeling magnetic resonance imaging to measure global and regional cerebral blood flow (CBF) before and after 20 min of cycling. The blood vessels’ ability to dilate, measured by cerebrovascular reactivity (CVR) to CO₂ inhalation, was measured at baseline and 25-min postexercise. Our data showed that CBF was selectively increased by 10–12% in the hippocampus 15, 40, and 60 min after exercise cessation, whereas CVR to CO₂ was unchanged in all regions. The absence of a corresponding change in hippocampal CVR suggests that the immediate and transient hippocampal adaptations observed after exercise are not driven by a mechanical vascular change and more likely represents an adaptive metabolic change, providing a framework for exploring the therapeutic potential of exercise-induced plasticity (neural, vascular, or both) in clinical and aged populations.

Exercise-Based Interventions for Internet Addiction: Neurobiological and Neuropsychological Evidence

With the increase in the number of internet users, the problems associated with excessive internet use have become increasingly obvious. Internet addiction can alter neurobiology, and its symptoms can be alleviated through exercise, but whether exercise exerts these effects through neurobiological pathways is unclear. Here, we reviewed the neurobiological mechanisms of exercise-based interventions against internet addiction by searching PubMed and Google Scholar for relevant research using such keywords as “exercise”, “internet addiction”, “hypothalamic-pituitary-adrenal axis”, “neurotrophin”, and “dopamine”. This review summarizes advances in our understanding of the neurobiological processes through which exercise can reduce internet addiction, and our analysis strengthens the idea that exercise-based interventions can be effective in this regard. The available evidence suggests that exercise can increase the levels of neurotrophic factors, cortisol, and neurotransmitters; improve the morphology of specific parts of the central nervous system, such as by stimulating hippocampal neurogenesis; protect the autonomic nervous system; and control the reward urge. In other words, exercise appears to mitigate internet addiction by regulating the neurobiology of the central and autonomic nervous systems. In this way, exercise-based interventions can be recommended for reducing internet addiction.

Exercise activates vagal induction of dopamine and attenuates systemic inflammation

Physical exercise is one of the most important factors improving quality of life, but it is not feasible for patients with morbidity or limited mobility. Most previous studies focused on high-intensity or long-term exercise that causes metabolic stress or physiological adaption, respectively. Here, we studied how moderate-intensity swimming affects systemic inflammation in 6-8 week old C57BL/6J male mice during endotoxemia. One-hour swimming prevented hypokalemia, hypocalcemia, attenuated serum levels of inflammatory cytokines, increased anti-inflammatory cytokines but affected neither IL6 nor glycemia before or after the endotoxic challenge. Exercise attenuated serum TNF levels by inhibiting its production in the spleen through a mechanism mediated by the subdiaphragmatic vagus nerve but independent of the splenic nerve. Exercise increased serum levels of dopamine, and adrenalectomy prevented the potential of exercise to induce dopamine and to attenuate serum TNF levels. Dopaminergic agonist type-1, fenoldopam, inhibited TNF production in splenocytes. Conversely, dopaminergic antagonist type-1, butaclamol, attenuated exercise control of serum TNF levels. These results suggest that vagal induction of dopamine may contribute to the anti-inflammatory potential of physical exercise.

Effects of an acute bout of physical exercise on reward functioning in healthy adults

Exercise has been proposed as a treatment for several psychiatric disorders. Exercise may act in part through beneficial effects on reward functioning, as it alters neurotransmitter levels in reward-related circuits. However, there has been little investigation of the effect of exercise on reward functions in humans. We hypothesized an acute bout of exercise would increase motivation for and pleasurable responses to rewards in healthy humans. In addition, we examined possible moderators of exercise's effects, including demographics, fitness and previous exercise experience. Thirty-five participants completed exercise and sedentary control sessions in randomized, counterbalanced order on separate days. Immediately after each activity, participants completed measures of motivation for and pleasurable responses to rewards, consisting of willingness to exert effort for monetary rewards and subjective responses to emotional pictures. Exercise did not increase motivation or pleasurable responses on average. However, individuals who had been running for more years showed increases in motivation for rewards after exercise, while individuals with less years running showed decreases. Further, individuals with higher resting heart rate variability reported lower arousal in response to all emotional pictures after exercise, while individuals with low heart rate variability reported increased arousal in response to all emotional pictures after exercise. General fitness did not have similar moderating effects. In conclusion, acute exercise improved reward functioning only in individuals accustomed to that type of exercise. This suggests a possible conditioned effect of exercise on reward functioning. Previous experience with the exercise used should be examined as a possible moderator in exercise treatment trials.

Cognitive function during exercise under severe hypoxia

Acute exercise has been demonstrated to improve cognitive function. In contrast, severe hypoxia can impair cognitive function. Hence, cognitive function during exercise under severe hypoxia may be determined by the balance between the beneficial effects of exercise and the detrimental effects of severe hypoxia. However, the physiological factors that determine cognitive function during exercise under hypoxia remain unclear. Here, we examined the combined effects of acute exercise and severe hypoxia on cognitive function and identified physiological factors that determine cognitive function during exercise under severe hypoxia. The participants completed cognitive tasks at rest and during moderate exercise under either normoxic or severe hypoxic conditions. Peripheral oxygen saturation, cerebral oxygenation, and middle cerebral artery velocity were continuously monitored. Cerebral oxygen delivery was calculated as the product of estimated arterial oxygen content and cerebral blood flow. On average, cognitive performance improved during exercise under both normoxia and hypoxia, without sacrificing accuracy. However, under hypoxia, cognitive improvements were attenuated for individuals exhibiting a greater decrease in peripheral oxygen saturation. Cognitive performance was not associated with other physiological parameters. Taken together, the present results suggest that arterial desaturation attenuates cognitive improvements during exercise under hypoxia.

The Acute Effects of Aerobic Exercise on the Functional Connectivity of Human Brain Networks

Although there is promising evidence that regular physical activity could counteract age-related decline in cognitive and brain function, the mechanisms for this neuroprotection remain unclear. The acute effects of exercise can provide insight into the mechanisms by which the brain adapts to habitual exercise by reflecting transient modulations of systems that would subsequently accumulate long-term adaptations through repeated training sessions. However, methodological limitations have hindered the mechanistic insight gained from previous studies examining acute exercise effects on the human brain. In the current study, we tested the plasticity of functional brain networks in response to a single stimulus of aerobic exercise using resting-state functional connectivity analyses. In a sample of healthy younger (N = 12; age = 23.2 years; 6 females) and older adults (N = 13; age = 66.3 years; 6 females), we found that 30 minutes of moderate-intensity aerobic cycling selectively increased synchrony among brain regions associated with affect and reward processing, learning and memory, and in regions important for attention and executive control. Importantly, these changes did not occur when the same participants completed a passive, motor-driven control condition. Our results suggest that these transient increases in synchrony serve as a possible avenue for systematically investigating the effects of various exercise parameters on specific brain systems, which may accelerate mechanistic discoveries about the benefits of exercise on brain and cognitive function.