Opioid Release after High-Intensity Interval Training in Healthy Human Subjects

Peripheral to brain and hippocampus crosstalk induced by exercise mediates cognitive and structural hippocampal adaptations

Endurance exercise leads to robust increases in memory and learning. Several exercise adaptations occur to mediate these improvements, including in both the hippocampus and in peripheral organs. Organ crosstalk has been becoming increasingly more present in exercise biology, and studies have shown that peripheral organs can communicate to the hippocampus and mediate hippocampal changes. Both learning and memory as well as other hippocampal functional-related changes such as neurogenesis, cell proliferation, dendrite morphology and synaptic plasticity are controlled by these exercise responsive peripheral proteins. These peripheral factors, also called exerkines, are produced by several organs including skeletal muscle, liver, adipose tissue, kidneys, adrenal glands and circulatory cells. Previous reviews have explored some of these exerkines including muscle-derived irisin and cathepsin B (CTSB), but a full picture of peripheral to hippocampus crosstalk with novel exerkines such as selenoprotein 1 (SEPP1) and platelet factor 4 (PF4), or old overlooked ones such as lactate and insulin-like growth factor 1 (IGF-1) is still missing. We provide 29 different studies of 14 different exerkines that crosstalk with the hippocampus. Thus, the purpose of this review is to explore peripheral exerkines that have shown to exert hippocampal function following exercise, demonstrating their particular effects and molecular mechanisms in which they could be inducing adaptations.

In search of the pleasure of moving through bodily re-explorations and interactions with the surroundings: a qualitative study on changed perceptions of physical activity in people with mild multiple sclerosis

INTRODUCTION

Reduced physical activity (PA) among people with multiple sclerosis (pwMS) with low disability is a significant concern. Developing healthcare to promote PA requires a comprehensive understanding of pwMS's perspectives.

PURPOSE

To explore how pwMS with mild disability perceive PA and the impact of individual, professional, social, and environmental aspects on their PA engagement.

METHODS

Qualitative, in-depth interviews with 27 pwMS (21 women, 6 men; aged 31-66; EDSS ≤ 3.5) were analyzed via systematic text condensation and informed by enactive theory.

RESULTS

Three categories were formed: Perception Shifts after Diagnosis: Participants adapted their perceptions to PA throughout their disease journey. Initial uncertainty concerning bodily capacities, prospects and safety reduced PA. Moving "correctly" during activities was emphasized to facilitate PA levels. Affective Experiences Drive Behavior: Pleasure associated with movement was a highlighted motivator, however, some experienced PA less rewarding after diagnosis. Discomfort and fear were barriers to PA engagement. The Surroundings Influence Perceptions: Participants sought social interactions and outdoor-environments to improve PA. Healthcare professionals were trusted to provide possibilities for PA, but early-stage and tailored follow-up was often lacking.

CONCLUSION

This study illuminates changed PA perceptions after MS diagnosis and how affect, shaped by personal, interpersonal, and environmental aspects, drive PA engagement. Moreover, it calls for early follow-up and the implementation of tailored healthcare throughout the disease course to promote PA engagement. Considering these findings, we have put forth a model aimed at fostering a nuanced comprehension of PA in pwMS with mild disabilities. Further development and exploration of this model is needed.

Comparative Effectiveness of Different Exercises for Reducing Pain Intensity in Primary Dysmenorrhea: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

BACKGROUND

Studies have demonstrated that exercise can mitigate the intensity of menstrual pain in primary dysmenorrhea, but the most effective type of exercise remains unclear. The objective of this systematic review and network meta-analysis was to evaluate the effectiveness of different exercise regimens in reducing pain associated with primary dysmenorrhoea.

METHODS

Randomized controlled trials investigating the relationship between menstrual pain and exercise were selected from major electronic databases until February 2, 2024. The primary outcome was the effect of exercise on pain intensity measured by the mean difference on a 10-cm visual analogue scale at 4 and 8 weeks after intervention. The secondary outcome was the difference in risk of dropout at 8 weeks. The study protocol was registered as INPLASY202330050.

RESULTS

This systematic review and network meta-analysis included 29 randomized controlled trials, which involved 1808 participants with primary dysmenorrhea. Exercise interventions included relaxation exercise, strength training, aerobic activity, yoga, mixed exercise, and the Kegel maneuver. Relaxation exercise was the most effective in reducing menstrual pain in 4 weeks (- 3.56; 95% confidence interval: - 5.03 to - 2.08). All exercise interventions were effective in reducing menstrual pain at 8 weeks, with reductions ranging from - 3.87 (95% CI - 5.51 to - 2.22) for relaxation exercise to - 2.75 (95% CI - 4.00 to - 1.51) for yoga, compared to the control group. Relaxation exercises were found to have a significantly lower dropout risk (- 0.11; 95% CI  - 0.20 to 0.02), while none of the exercise types was associated with a higher dropout risk than the control group.

CONCLUSION

All exercise interventions were effective in reducing menstrual pain in primary dysmenorrhea after 8 weeks of intervention. However, relaxation exercise was found to be the most effective intervention at 4 and 8 weeks and had the lowest risk of dropout.

Fractional amplitude of low-frequency fluctuations associated with μ-opioid and dopamine receptor distributions in the central nervous system after high-intensity exercise bouts

Introduction

Dopaminergic, opiod and endocannabinoid neurotransmission are thought to play an important role in the neurobiology of acute exercise and, in particular, in mediating positive affective responses and reward processes. Recent evidence indicates that changes in fractional amplitude of low-frequency fluctuations (zfALFF) in resting-state functional MRI (rs-fMRI) may reflect changes in specific neurotransmitter systems as tested by means of spatial correlation analyses.

Methods

Here, we investigated this relationship at different exercise intensities in twenty young healthy trained athletes performing low-intensity (LIIE), high-intensity (HIIE) interval exercises, and a control condition on three separate days. Positive And Negative Affect Schedule (PANAS) scores and rs-fMRI were acquired before and after each of the three experimental conditions. Respective zfALFF changes were analyzed using repeated measures ANOVAs. We examined the spatial correspondence of changes in zfALFF before and after training with the available neurotransmitter maps across all voxels and additionally, hypothesis-driven, for neurotransmitter maps implicated in the neurobiology of exercise (dopaminergic, opiodic and endocannabinoid) in specific brain networks associated with "reward" and "emotion."

Results

Elevated PANAS Positive Affect was observed after LIIE and HIIE but not after the control condition. HIIE compared to the control condition resulted in differential zfALFF decreases in precuneus, temporo-occipital, midcingulate and frontal regions, thalamus, and cerebellum, whereas differential zfALFF increases were identified in hypothalamus, pituitary, and periaqueductal gray. The spatial alteration patterns in zfALFF during HIIE were positively associated with dopaminergic and μ-opioidergic receptor distributions within the 'reward' network.

Discussion

These findings provide new insight into the neurobiology of exercise supporting the importance of reward-related neurotransmission at least during high-intensity physical activity.

The endogenous opioid system in the medial prefrontal cortex mediates ketamine's antidepressant-like actions

Recent studies have implicated the endogenous opioid system in the antidepressant actions of ketamine, but the underlying mechanisms remain unclear. We used a combination of pharmacological, behavioral, and molecular approaches in rats to test the contribution of the prefrontal endogenous opioid system to the antidepressant-like effects of a single dose of ketamine. Both the behavioral actions of ketamine and their molecular correlates in the medial prefrontal cortex (mPFC) are blocked by acute systemic administration of naltrexone, a competitive opioid receptor antagonist. Naltrexone delivered directly into the mPFC similarly disrupts the behavioral effects of ketamine. Ketamine treatment rapidly increases levels of β-endorphin and the expression of the μ-opioid receptor gene (Oprm1) in the mPFC, and the expression of gene that encodes proopiomelanocortin, the precursor of β-endorphin, in the hypothalamus, in vivo. Finally, neutralization of β-endorphin in the mPFC using a specific antibody prior to ketamine treatment abolishes both behavioral and molecular effects. Together, these findings indicate that presence of β-endorphin and activation of opioid receptors in the mPFC are required for the antidepressant-like actions of ketamine.

Sweating for Sobriety: Exploring the Relationship Between Exercise Engagement and Substance Use Disorders

Despite various interventions available for substance use disorders, relapse rates remain substantial and, therefore, alternative strategies for attenuating dependence are needed. This study examined the associations between exercise frequency, illicit substance use, and dependence severity among a large sample of people who use drugs. The study utilized data from the Global Drug Survey 2018 (N = 57,110) to investigate the relationship between exercise frequency, illicit substance use, and substance dependence severity. Binomial regressions were employed to examine the relationship between exercise and SDS scores for 9 drugs. Greater exercise frequency correlated with reduced severity of substance dependence for specific drugs: cannabis (χ2 = 14.75, p < .001), MDMA (χ2 = 4.73, p = .029), cocaine (χ2 = 8.37, p = .015), amphetamine powder (χ2 = 6.39, p = .041), and methamphetamine (χ2 = 15.17, p < .001). These findings suggest a potential link between exercise and reduced substance use dependency. Further research is needed to understand the complex dynamics between exercise and substance use, considering potential bidirectional relationships and concurrent factors.

Effects of aerobic exercise or Tai Chi Chuan interventions on problematic mobile phone use and the potential role of intestinal flora: A multi-arm randomized controlled trial

BACKGROUND

Problematic use of mobile phones (PMPU) has been described as a serious public health issue.

METHODS

This study was a parallel three-arm randomized controlled trial and has completed registration (ClinicalTrials.gov Identifier: NCT05843591). Ninety college students with PMPU were randomly assigned to the aerobic exercise group (AE group, n = 30), the Tai Chi Chuan group (TCC group, n = 30), or the wait-list control group (WLC group, n = 30). At the end of the intervention, stool samples from the study participants were collected for biological analysis based on 16 S rDNA amplicon sequencing technology. The primary outcome was addiction symptoms assessed by the Smartphone Addiction Scale-Short Version (SAS-SV). The secondary outcomes are emotional symptoms, physical symptoms, and flora species.

RESULTS

Compared with the WLC group, the AE and TCC groups showed reductions in PMPU levels, physical and mental fatigue, but there was no difference between the two groups. Moreover, the effect of increasing self-esteem embodied in the TCC group was not present in the AE group. Compared to the WLC group, the relative abundance of Bacteroidaceae and Bacteroides were lower in the AE group, while the relative abundance of Erysipelotrichaceae and Alistipes were lower in the TCC group. And the relative abundance of Bacteroidaceae, Bacteroides, and Alistipes were significantly and negatively correlated with the decline in PMPU scores.

CONCLUSION

AE or TCC is an effective, safe and efficient intervention for college students with PMPU, providing some physiological and psychological benefits and having some impact on their intestinal flora.

Social media consumption and depressive symptoms during the COVID-19 lockdown: the mediating effect of physical activity

Introduction

Social media platforms played a critical role during the COVID-19 pandemic. This study aimed to explore: (1) the changes in social media consumption patterns, physical activity levels/sedentary behavior, and depressive symptoms, and (2) how the changes in social media consumption patterns predict the changes in depressive symptoms while investigating the mediating role of changes in physical activity levels/sedentary behavior between before, and after the COVID-19 lockdown among U.S. adults with different age clusters.

Methods

A total of 695 U.S. participants completed an online questionnaire via MTurk, and participants were asked to recall their social media consumption patterns, physical activity/sedentary behavior, depressive symptoms in January and May of 2020 while covariates included non-physical activity health behavior including diet quality, alcohol consumption, smoking, and sleep quality.

Results

The results of Bayesian significance testing of changes showed that the older participants tended to spend more time with content-focused social media platforms during the lockdown. While significantly increased sitting time was reported by all age clusters, no significant changes were found in activity levels. Additionally, the middle-aged and older participants reported significantly higher depressive symptoms. The findings of a multigroup structural analysis showed the significant mediating effect of moderate-to-vigorous physical activity on the relationship between changes in social media consumption and depressive symptoms.

Discussion

This study highlights the need for targeting specific social media platforms for older adults and the importance of moderate-to-vigorous physical activity to alleviate the mental health issues resulting from social media consumption. The result of this study also highlights the need for sport-based intervention programs in the future and the need for more social media campaigns at the institution/organization levels established by public health stakeholders and policy makers to promote physical activity and maximize population perception and reach during the pandemic.

The endogenous opioid system in the medial prefrontal cortex mediates ketamine's antidepressant-like actions

Recent studies have implicated the endogenous opioid system in the antidepressant actions of ketamine, but the underlying mechanisms remain unclear. We used a combination of pharmacological, behavioral, and molecular approaches in rats to test the contribution of the prefrontal endogenous opioid system to the antidepressant-like effects of a single dose of ketamine. Both the behavioral actions of ketamine and their molecular correlates in the medial prefrontal cortex (mPFC) were blocked by acute systemic administration of naltrexone, a competitive opioid receptor antagonist. Naltrexone delivered directly into the mPFC similarly disrupted the behavioral effects of ketamine. Ketamine treatment rapidly increased levels of β-endorphin and the expression of the μ-opioid receptor gene (Oprm1) in the mPFC, and the expression of the gene that encodes proopiomelanocortin, the precursor of β-endorphin, in the hypothalamus, in vivo. Finally, neutralization of β-endorphin in the mPFC using a specific antibody prior to ketamine treatment abolished both behavioral and molecular effects. Together, these findings indicate that presence of β-endorphin and activation of opioid receptors in the mPFC are required for the antidepressant-like actions of ketamine.

Modulation of pain perceptions following treadmill running with different intensities in females

We aimed to compare the effects of three intensities of treadmill running on exercise-induced hypoalgesia (EIH) in healthy individuals. We anticipated that the primary and secondary changes in pain perception and modulation may differ between running intensities. Sixty-six women were randomly assigned to one of three treadmill running intensities for 35 min: 40% reserved heart rate (HRR), 55% HRR, or 70% HRR. The effects of EIH were assessed using pressure pain thresholds (PPT) and tolerance thresholds (PPTol). We measured conditional pain modulation (CPM). Compared with baseline, PPT and PPTol significantly increased in all groups during running and at the 5-10-min follow-up. The PPT and PPTol changes in the moderate- and low-intensity groups were significantly higher than those in the high-intensity group during running and 24 h after running, while the CPM responses of the high-intensity group were significantly reduced at the 24-h follow-up. Moderate- and low-intensity running may elicit significant primary and secondary (persisting over 24 h) EIH effects and increase CPM responses in females. However, high-intensity running induced only limited analgesic effects and reduced CPM responses, which may be attributed to the activation of endogenous pain modulation.

A Molecular Toolbox of Positron Emission Tomography Tracers for General Anesthesia Mechanism Research

With appropriate radiotracers, positron emission tomography (PET) allows direct or indirect monitoring of the spatial and temporal distribution of anesthetics, neurotransmitters, and biomarkers, making it an indispensable tool for studying the general anesthesia mechanism. In this Perspective, PET tracers that have been recruited in general anesthesia research are introduced in the following order: 1) ¹¹C/¹⁸F-labeled anesthetics, i.e., PET tracers made from inhaled and intravenous anesthetics; 2) PET tracers targeting anesthesia-related receptors, e.g., neurotransmitters and voltage-gated ion channels; and 3) PET tracers for studying anesthesia-related neurophysiological effects and neurotoxicity. The radiosynthesis, pharmacodynamics, and pharmacokinetics of the above PET tracers are mainly discussed to provide a practical molecular toolbox for radiochemists, anesthesiologists, and those who are interested in general anesthesia.

Extraordinary claims in the literature on high-intensity interval training (HIIT): III. Critical analysis of four foundational arguments from an interdisciplinary lens

Kinesiology aspires to be an integrated, interdisciplinary field that studies human movement from multiple perspectives. However, the main societal deliverables of the field, namely exercise prescriptions and physical activity recommendations, still reflect fragmentation, placing more emphasis on physiological outcomes than on behavioral and other considerations. Recently, researchers have called for the introduction of High-Intensity Interval Training (HIIT) to the domain of public health, based on the argument that HIIT can maximize fitness and health benefits for a fraction of the time recommended by the prevailing model of physical activity in public-health guidelines. Here, we show that an unintended side-effect of arguments underpinning the implementation of HIIT in the domain of public health might have been the exacerbation of segmentation. To highlight the value of interdisciplinarity, four foundational claims in support of HIIT are critiqued by tapping into cognate literatures: (1) the primary reason people do not exercise is lack of time, (2) HIIT is relevant to public health, (3) HIIT is being proposed as merely another option, so there is no basis for controversy, and (4) HIIT is safe and well tolerated. These claims are contradicted by credible lines of evidence. To improve the accuracy and effectiveness of its public claims, kinesiology should remain committed to the ideals of integration and interdisciplinarity.

[Exercise for the promotion of mental health II: Putative mechanisms, recommendations, and scientific challenges]

The idea of applying various forms of physical activity for the betterment of physical health and the reduction of chronic medical conditions is ubiquitous. Despite evidence of successful applications of physical activity for improvement of mental health dating back to antiquity, it has until recent years remained unconventional to consider exercise as an intervention strategy for various mental health conditions. The past two decades, however, have seen a relative explosion of interest in understanding and applying various programs and forms of exercise to improve mental health. Here, our purpose is to provide a comprehensive and updated overview of the application of exercise as a strategy for improving mental health. In the present paper we first summarize contemporary research regarding short- and long-term impacts of exercise on mental health. Then an overview of the putative mechanisms and neurobiological bases underpinning the beneficial effects of exercise is provided. Finally, we suggest directions for future research as well as a series of concrete recommendations for clinicians who wish to prescribe physical activity as part of patient mental health management.

Applying Scientific Rationale to the Current Perceptions and Explanations of Massage and Miscarriage in the First Trimester

Miscarriage is a relatively common occurrence, impacting 8-15% of clinically recognised pregnancies, and up to 30% of all conceptions. The public perception of the risk factors associated with miscarriage does not match the evidence. Evidence indicates that there are very few modifiable factors to prevent miscarriage, and the majority of the time little could have been done to prevent a spontaneous miscarriage. However, the public perception is that consuming drugs, lifting a heavy object, previous use of an intrauterine device, or massage can all contribute to miscarriage. While misinformation about the causes and risk factors of miscarriage continues to circulate, pregnant women will experience confusion about what activities they can (and cannot) do in early pregnancy, including receiving a massage. Pregnancy massage is an important component of massage therapy education. The resources that underpin pregnancy massage coursework consist of educational print content that includes direction and caution that massage in the first trimester, if done 'incorrectly' or in the 'wrong' location, can contribute to adverse outcomes such as miscarriage. The most common statements, perceptions and explanations for massage and miscarriage cover three broad areas: 1) maternal changes from massage affects the embryo/fetus; 2) massage leads to damage of the fetus/placenta; and 3) aspects of the massage treatment in the first trimester initiate contractions. The goal of this paper is to use scientific rationale to critically consider the validity of the current perceptions and explanations of massage therapy and miscarriage. Whilst direct evidence from clinical trials was lacking, considerations of physiological mechanisms regulating pregnancy and known risk factors associated with miscarriage provide no evidence that massage in pregnancy would increase a patient's risk of miscarriage. This scientific rationale should be addressed when teaching pregnancy massage courses.

Effect of Exercise on β-Endorphin and Its Receptors in Myasthenia Gravis Patients

This is a prospective observational study evaluating the change in β-endorphin (BE) and its receptors following exercise in patients with myasthenia gravis (MG) and their association with clinical improvement. Fifteen patients with mild to moderate MG, aged 16-70 years, who were able to do 6-Minute Walk Test (6-MWT) and had MG Quality of Life-15 (MGQoL-15) ≤ 45 without any contraindication for exercise were included. The patients walked 30 min daily for 3 months. The primary outcome at 3 months was > 50% improvement in MGQoL-15 from the baseline, and the secondary outcomes were MG Activities of Daily Living (MGADL), Hospital Anxiety and Depression Scale (HADS), number of steps, and distance covered on 6-MWT and adverse events. Plasma BE level, μ-opioid receptor (MOR), and δ-opioid receptor (DOR) were measured on admission and at 1 and 3 months. Twelve age- and gender-matched healthy controls who were not on regular exercise were included for comparison of BE, MOR, and DOR levels. Plasma BE level (P = 0.007) and DOR expression (P = 0.001) were lower in MG patients compared to the healthy controls. After 3 months of exercise, 6 patients improved. Plasma BE, MOR, and DOR levels increased in the first and decreased in the third month. MGQoL-15 (P < 0.001), HADS (P < 0.0001), number of steps (P < 0.007), distance (P = 0.030), and MGADL (P < 0.001) significantly improved compared to baseline. At 3 months, MGQoL-15 was associated with HADS score (P = 0.001), reduced depression (P = 0.013), MGADL (P = 0.035), and distance travelled on the 6-WMW test (P = 0.050). The improvement in depression was associated with higher BE level.

Athlete level, sport-type, and gender influences on training, mental health, and sleep during the early COVID-19 lockdown in Malaysia

Purpose: We evaluated the extent of changes in training practices, recovery, mental health, and sleep patterns of athletes during the early COVID-19 lockdown in a single country-cohort. Methods: A total of 686 athletes (59% male, 41% female; 9% World Class, 28% International, 29% National, 26% State, 8% Recreational) from 50 sports (45% individual, 55% team) in Malaysia completed an online, survey-based questionnaire study. The questions were related to training practices (including recovery and injury), mental health, and sleep patterns. Results: Relative to pre-lockdown, training intensity (-34%), frequency (-20%, except World-Class), and duration (-24%-59%, especially International/World-Class) were compromised, by the mandated lockdown. During the lockdown, more space/access (69%) and equipment (69%) were available for cardiorespiratory training, than technical and strength; and these resources favoured World-Class athletes. Most athletes trained for general strength/health (88%) and muscular endurance (71%); and some used innovative/digital training tools (World-Class 48% vs. lower classification-levels ≤34%). More World-Class, International, and National athletes performed strength training, plyometrics, and sport-specific technical skills with proper equipment, than State/Recreational athletes. More females (42%) sourced training materials from social media than males (29%). Some athletes (38%) performed injury prevention exercises; 18% had mild injuries (knees 29%, ankles 26%), and 18% received a medical diagnosis (International 31%). Lower-level athletes (e.g., State 44%) disclosed that they were mentally more vulnerable; and felt more anxious (36% vs. higher-levels 14%-21%). Sleep quality and quantity were "normal" (49% for both), "improved" (35% and 27%), and only 16% and 14% (respectively) stated "worsened" sleep. Conclusion: Lockdown compromised training-related practices, especially in lower-level athletes. Athletes are in need of assistance with training, and tools to cope with anxiety that should be tailored to individual country requirements during lockdown situations. In particular, goal-driven (even if it is at home) fitness training, psychological, financial, and lifestyle support can be provided to reduce the difficulties associated with lockdowns. Policies and guidelines that facilitate athletes (of all levels) to train regularly during the lockdown should be developed.

Protective effects of physical activity on mental health outcomes during the COVID-19 pandemic

The COVID-19 pandemic has been linked with increased reports of depression, anxiety, and stress. Stay-at-home directives during the pandemic-imposed lifestyle changes, including eating and sedentary behaviors that can further undermine mental health outcomes. Physical activity is a vital component for metabolic health, as well as for mental health by serving as an active coping strategy to manage stress and promote resilience. Global reports of increased sedentary leisure behaviors have been associated with feelings of depression and anxiety, but it unclear whether the relationship between physical activity and depression or anxiety persists over time. In this longitudinal study, we investigated (i) whether physical activity at the onset of the pandemic was related to feelings of depression or anxiety over time and (ii) whether this relationship was mediated by stress appraisals during the pandemic. We surveyed 319 adults living in Canada or the United States to assess physical activity, stress appraisals, and mental health outcomes at two time points over a 6-month period. We found a reduction in leisure-time physical activity that was linked to subsequent feelings of depression. Furthermore, individuals with lower levels of physical activity were more likely to appraise their COVID-19 situation to be uncontrollable at pandemic onset and as the pandemic continued. Stress appraisals of threat and uncontrollability were also positively related to feelings of depression. Modelling these three factors together showed that appraising a situation as uncontrollable mediated the relationship between initial physical activity and subsequent depressive feelings. Although correlational, these data highlight the protective role of leisure-time physical activity against worsened mental health outcomes during periods of prolonged stress.

Dopamine D2/3-receptor availability and its association with autonomous motivation to exercise in older adults: An exploratory [11C]-raclopride study

Background

Autonomous motivation to exercise occurs when the activity is voluntary and with a perceived inherent satisfaction from the activity itself. It has been suggested that autonomous motivation is related to striatal dopamine D2/3-receptor (D2/3R) availability within the brain. In this study, we hypothesized that D2/3R availability in three striatal regions (nucleus accumbens, caudate nucleus, and putamen) would be positively associated with self-reported autonomous motivation to exercise. We also examined this relationship with additional exploratory analyses across a set of a priori extrastriatal regions of interest (ROI).

Methods

Our sample comprised 49 older adults (28 females) between 64 and 78 years of age. The D2/3R availability was quantified from positron emission tomography using the non-displaceable binding potential of [11C]-raclopride ligand. The exercise-related autonomous motivation was assessed with the Swedish version of the Behavioral Regulations in Exercise Questionnaire-2.

Results

No significant associations were observed between self-reported autonomous motivation to exercise and D2/3R availability within the striatum (nucleus accumbens, caudate nucleus, and putamen) using semi-partial correlations controlling for ROI volume on D2/3R availability. For exploratory analyses, positive associations were observed for the superior (r = 0.289, p = 0.023) and middle frontal gyrus (r = 0.330, p = 0.011), but not for the inferior frontal gyrus, orbitofrontal cortex, anterior cingulate cortex, or anterior insular cortex.

Conclusion

This study could not confirm the suggested link between striatal D2/3R availability and subjective autonomous motivation to exercise among older adults. The exploratory findings, however, propose that frontal brain regions may be involved in the intrinsic regulation of exercise-related behaviors, though this has to be confirmed by future studies using a more suitable ligand and objective measures of physical activity levels.

What is the efficacy of aerobic exercise versus strength training in the treatment of migraine? A systematic review and network meta-analysis of clinical trials

Background

Multiple clinical trials with different exercise protocols have demonstrated efficacy in the management of migraine. However, there is no head-to-head comparison of efficacy between the different exercise interventions.

Methods

A systematic review and network meta-analysis was performed involving all clinical trials which determined the efficacy of exercise interventions in reducing the frequency of monthly migraine. Medical journal search engines included Web of Science, PubMed, and Scopus spanning all previous years up to July 30, 2022. Both aerobic and strength/resistance training protocols were included. The mean difference (MD, 95% confidence interval) in monthly migraine frequency from baseline to end-of-intervention between the active and control arms was used as an outcome measure. Efficacy evidence from direct and indirect comparisons was combined by conducting a random effects model network meta-analysis. The efficacy of the three exercise protocols was compared, i.e., moderate-intensity aerobic exercise, high-intensity aerobic exercise, and strength/resistance training. Studies that compared the efficacy of migraine medications (topiramate, amitriptyline) to exercise were included. Additionally, the risk of bias in all included studies was assessed by using the Cochrane Risk of Bias version 2 (RoB2).

Results

There were 21 published clinical trials that involved a total of 1195 migraine patients with a mean age of 35 years and a female-to-male ratio of 6.7. There were 27 pairwise comparisons and 8 indirect comparisons. The rank of the interventions was as follows: strength training (MD = -3.55 [− 6.15, − 0.95]), high-intensity aerobic exercise (-3.13 [-5.28, -0.97]), moderate-intensity aerobic exercise (-2.18 [-3.25, -1.11]), topiramate (-0.98 [-4.16, 2.20]), placebo, amitriptyline (3.82 [− 1.03, 8.68]). The RoB2 assessment showed that 85% of the included studies demonstrated low risk of bias, while 15% indicated high risk of bias for intention-to-treat analysis. Sources of high risk of bias include randomization process and handling of missing outcome data.

Conclusion

Strength training exercise regimens demonstrated the highest efficacy in reducing migraine burden, followed by high-intensity aerobic exercise.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01503-y.

Aerobic Fitness Is Associated with Cerebral μ-Opioid Receptor Activation in Healthy Humans

INTRODUCTION

Central μ-opioid receptors (MORs) modulate affective responses to physical exercise. Individuals with higher aerobic fitness report greater exercise-induced mood improvements than those with lower fitness, but the link between cardiorespiratory fitness and the MOR system remains unresolved. Here we tested whether maximal oxygen uptake (V̇O2peak) and physical activity level are associated with cerebral MOR availability and whether these phenotypes predict endogenous opioid release after a session of exercise.

METHODS

We studied 64 healthy lean men who performed a maximal incremental cycling test for V̇O2peak determination, completed a questionnaire assessing moderate-to-vigorous physical activity (MVPA; in minutes per week), and underwent positron emission tomography with [11C]carfentanil, a specific radioligand for MOR. A subset of 24 subjects underwent additional positron emission tomography scan also after a 1-h session of moderate-intensity exercise and 12 of them also after a bout of high-intensity interval training.

RESULTS

Higher self-reported MVPA level predicted greater opioid release after high-intensity interval training, and both V̇O2peak and MVPA level were associated with a larger decrease in cerebral MOR binding after aerobic exercise in the ventral striatum, orbitofrontal cortex, and insula. That is, more trained individuals showed greater opioid release acutely after exercise in brain regions especially relevant for reward and cognitive processing. Fitness was not associated with MOR availability.

CONCLUSIONS

We conclude that regular exercise training and higher aerobic fitness may induce neuroadaptation within the MOR system, which might contribute to improved emotional and behavioral responses associated with long-term exercise.

Diels–Alder Adducts of Morphinan-6,8-Dienes and Their Transformations

6,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a rigid molecular structure. These compounds represent an important family of opioid receptor ligands in which the 6,14-etheno bridged structural motif originates from a [4 + 2] cycloaddition of morphinan-6,8-dienes with dienophiles. Certain 6,14-ethenomorphinans having extremely high affinity for opioid receptors are often non-selective for opioid receptor subtypes, but this view is now undergoing some revision. The agonist 20R-etorphine and 20R-dihydroetorphine are several thousand times more potent analgesics than morphine, whereas diprenorphine is a high-affinity non-selective antagonist. The partial agonist buprenorphine is used as an analgesic in the management of post-operative pain or in substitution therapy for opiate addiction, sometimes in combination with the non-selective antagonist naloxone. In the context of the current opioid crisis, we communicated a summary of several decades of work toward generating opioid analgesics with lesser side effects or abuse potential. Our summary placed a focus on Diels–Alder reactions of morphinan-6,8-dienes and subsequent transformations of the cycloadducts. We also summarized the pharmacological aspects of radiolabeled 6,14-ethenomorphinans used in molecular imaging of opioid receptors.

μ-opioid receptor availability is associated with sex drive in human males

The endogenous mu-opioid receptor (MOR) system modulates a multitude of social and reward-related functions, and exogenous opiates also influence sex drive in humans and animals. Sex drive shows substantial variation across humans, and it is possible that individual differences in MOR availability underlie interindividual of variation in human sex drive. We measured healthy male subjects’ (n = 52) brain’s MOR availability with positron emission tomography (PET) using an agonist radioligand, [¹¹C]carfentanil, that has high affinity for MORs. Sex drive was measured using self-reports of engaging in sexual behaviour (sex with partner and masturbating). Bayesian hierarchical regression analysis revealed that sex drive was positively associated with MOR availability in cortical and subcortical areas, notably in caudate nucleus, hippocampus, and cingulate cortices. These results were replicated in full-volume GLM analysis. These widespread effects are in line with high spatial autocorrelation in MOR expression in human brain. Complementary voxel-based morphometry analysis (n = 108) of anatomical MR images provided limited evidence for positive association between sex drive and cortical density in the midcingulate cortex. We conclude that endogenous MOR tone is associated with individual differences in sex drive in human males.

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

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

The Influence of Exercise Intensity on Psychosocial Outcomes in Musculoskeletal Disorders: A Systematic Review

CONTEXT

Psychosocial parameters play an important role in the onset and persistence of chronic musculoskeletal disorders (CMSDs). Exercise therapy is a valuable therapeutic modality as part of CMSD rehabilitation. Hereby, exercise intensity is an important factor regarding changes in pain and disability in multiple CMSDs. However, the impact of exercise intensity on psychosocial outcomes remains poorly explored.

OBJECTIVE

To identify the effects of different modes of exercise intensity on psychosocial outcomes in persons with CMSDs.

DATA SOURCES

A systematic search was conducted up to November 2020 using the following databases: PubMed/MEDline, PEDro, Cochrane Library, and Web of Science.

STUDY SELECTION

Studies reporting exercise therapy in CMSDs with a predefined display of exercise intensity and an evaluation of at least 1 psychosocial outcome were included.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 2a.

DATA EXTRACTION

Data regarding demographics, exercise intensity, and psychosocial outcomes were included in a descriptive analysis. Methodological quality was assessed using the PEDro scale and Critical Appraisal Skills Programme (CASP) checklist.

RESULTS

A total of 22 studies, involving 985 participants (with fibromyalgia, chronic low back pain, knee osteoarthritis, psoriatic arthritis, and axial spondyloarthritis) were included (mean PEDro score = 5.77/10). The most common psychosocial outcomes were quality of life (QoL) (n = 15), depression (n = 10), and anxiety (n = 9). QoL improved at any exercise intensity in persons with fibromyalgia. However, persons with fibromyalgia benefit more from exercising at low to moderate intensity regarding anxiety and depression. In contrast, persons with chronic low back pain benefit more from exercising at a higher intensity regarding QoL, anxiety, and depression. Other CMSDs only showed limited or conflicting results regarding the value of certain exercise intensities.

CONCLUSION

Psychosocial outcomes are influenced by the intensity of exercise therapy in fibromyalgia and chronic low back pain, but effects differ across other CMSDs. Future research is necessary to determine the exercise intensity that yields optimal exercise therapy outcomes in specific CMSDs.

Neuroprotective Effect of HIIT against GFAP Hypertrophy through Mitochondrial Dynamics in APP/PS1 Mice

Alzheimer's disease (AD) is characterized by the accumulation of β-amyloid (Aβ) plaques and tau neurofibrillary tangles in the brain. Although the exact details of the neuronal protective effect of high-intensity interval training (HIIT) on AD remain unclear, the preclinical phase of AD appears to be the important time point for such intervention. The described experiment investigates the neuroprotective effect of HIIT on AD in APP/PS1 mice. In total, 14 C57BL6 healthy control (C) mice and 14 APP/PS1 AD mice were each randomly assigned into two groups, one that did not participate in HIIT (C and AD groups, respectively) and the other subject to HIIT intervention (control HIIT (CE) and AD HIIT (ADE) groups, respectively). Visualization of hippocampal neuronal cells via HE and Congo red staining showed significant improvement in cell status and a significant reduction in amyloidosis in ADE compared with AD. The results of behavioral analysis show that the HIIT intervention significantly improved cognitive decline and reduced spatial exploration in both the C and AD groups. Immunofluorescence showed that the overall brain and the hippocampus of aged rats in the C and AD groups had different degrees of neuroglial responses and astrocyte GFAP proliferation and hypertrophy, with obvious improvement in the CE and ADE groups after 10 weeks of HIIT intervention. These results show that HIIT significantly improves the status of mitochondrial kinetic proteins and related proteins, with the mechanism differing between the normal aging C and the AD groups. 10 weeks of HIIT improved the imbalance in mitochondrial dynamics present in normal control mice and in AD mice. We conclude that preclinical training intervention has a significant positive effect on the exploratory behavior and cognitive functioning of mice.

Physical Therapies for Psychosomatic Symptoms and Quality of Life Induced by Aromatase Inhibitors in Breast Cancer Patients: A Systematic Review and Meta-Analysis

Objective

To evaluate the effects of Physical Therapies (PTs) on improvement in psychosomatic symptoms and quality of life (QOL) in breast cancer patients.

Data Sources

Seven databases (MEDLINE, EMBASE, Cochrane CENTRAL, China National Knowledge Infrastructure, Wangfang, VIP, and China Biology Medicine disc databases) were systematically searched from the database inception through May 18, 2021.

Study Selection

Randomized controlled trials (RCTs) which compared acupuncture or exercise with a sham control or usual care for the treatment of aromatase inhibitors (AIs)-related psychosomatic symptoms and QOL.

Data Extraction and Synthesis

Data were screened and extracted independently using predesigned forms. The quality of RCTs was assessed with the Cochrane Handbook for Systematic Reviews of Interventions. The effect size was calculated via random-effects modeling. The quality of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation approach.

Main Outcomes and Measures

The score of pain was measured with BPI scale and Western Ontario and the McMaster Universities Index (WOMAC) scale. Emotional state was measured with Pittsburgh Sleep Quality Index (PSQI), Hospital Anxiety and Depression Scale (HADS-A), and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue). The QOL score was measured by self-reported measurements, including the Functional Assessment of Cancer Therapy-General (FACT-G) scale and 36-Item Short Form Survey (SF-36) scale.

Results

Eleven RCTs (with 830 patients) were included in the systematic review, and data from 10 RCTs (with 798 patients) were used in the meta-analysis. Results showed acupuncture significantly reduced worst pain scores (P < 0.00001, I² = 83.5%) [SMD = −0.81, 95% CI (−1.51, −0.11)], but the effect of exercise therapies was not significant in overall change in worst pain scores (P =0.006, I² = 72.3%) [SMD = −0.30, 95% CI (−0.76, 0.16)]. Both acupuncture and exercise resulted in little to no difference in overall change in HADS-A subscale (P = 0.026<0.05, I² = 79.8%) [WMD = −0.21, 95% CI (−3.44, 3.03)], PSQI subscale (P = 0.488, I² = 0%) [WMD = 0.98, 95% CI (−0.57, 2.53)], and FACIT-Fatigue subscale (P = 0.022<0.05, I² = 81.0%) [WMD = 1.6, 95% CI (−5.75, 8.94)]. Exercise (compared with usual care) was associated with improving overall change in health-related QOL (subscales of SF-36 tool) (P = 0, I² = 72.1%) [WMD = 7.97, 95% CI (5.68, 10.25)] and cancer-specific QOL (subscales of FACT-G tool) (P = 0.304, I² = 16%) [WMD = 1.16, 95% CI (0.34, 1.97)].

Conclusions and Relevance

This systematic review and meta-analysis suggested that based on moderate-level evidence, acupuncture was associated with significant reductions in pain intensity, and exercise might improve QOL in breast cancer patients treated with AIs. However, in psychosomatic symptoms such as anxiety, sleep disturbance, and fatigue, acupuncture and exercise training did not result in significant improvements.

A Comparison Between the Effect of Combined Chain Exercises Plus Kinesio Taping With Combined Chain Exercises Alone in Knee Osteoarthritis: A Randomized Clinical Trial

OBJECTIVE

This study aimed to examine the effect of Kinesio taping as an adjunct to combined chain exercises compared with combined chain exercises alone in the management of individuals with knee osteoarthritis.

METHODS

A total of 60 (27 male, 33 female) individuals (age range = 50-71 yrs and mean age = 54.26 ± 8.83 yrs) diagnosed as having mild to moderate knee osteoarthritis (based on the Kellgren and Lawrence grade I-III classification) were randomly allocated into two groups with 30 participants each in the Kinesio taping + combined chain exercises and combined chain exercises groups. Participants in the Kinesio taping + combined chain exercises group received Kinesio taping plus combined chain exercises and those in the combined chain exercises group received only combined chain exercises. Each participant was assessed for pain, range of motion, functional mobility, and quality of life at baseline and after 8 wks of intervention. A mixed-design multivariate analysis of variance was used to analyze the treatment effect.

RESULTS

No significant differences were observed in the baseline characteristics of participants in both groups. The result indicated that there was a significant time effect for all outcomes, with a significant interaction between time and intervention (P < 0.001). The Bonferroni post hoc analyses of time and intervention effects indicated that the Kinesio taping + combined chain exercises group improved significantly better than the combined chain exercises group in all outcomes, pain (mean = 2.01 [0.64] vs. 3.94 [1.12], F[df] = 5.466[1,58], P = 0.011), flexion range of motion (mean = 121.15 [2.07] vs. 104.28 [3.24], F[df] = 26.722[1,58], P < 0.001), functional mobility (mean = 19.47 [1.95] vs. 31.01 [2.39], F[df] = 29.436[1,58], P < 0.001), and quality of life (mean = 68.76 [3.19] vs. 45.62 [2.87], F[df] = 71.984[1,58], P < 0.001), after 8 wks of intervention.

CONCLUSIONS

The findings of this study concluded that Kinesio taping + combined chain exercises and combined chain exercises were both effective but Kinesio taping plus combined chain exercises was more effective in the management of individuals with knee osteoarthritis.

TRIAL REGISTRATION

Pan African Clinical Trial Registry: PACTR201810603949411.

Influence of Single Bouts of Aerobic Exercise on Dual-Tasking Performance in Healthy Adults

Dual-tasking performance (DTP) is critical for most real-life activities. Interventions to improve DTP would be clinically valuable. This study investigated effects of single-bouts of two different aerobic exercises on the performance of Extended cognitive Timed-Up and Go (ETUGcog), a dual-task test involving concurrent performance of a physical (ETUG) and cognitive (counting backwards serial 7 s) task. Twenty-two adults performed single bouts of high-intensity interval training (HIIT) and moderate-intensity exercise (MIE), separately. ETUGcog was performed before, immediately following, and 24 hours after each exercise. Number and rates of correct serial 7 s were significantly higher 24 hours after HIIT, with no difference in times to complete ETUGcog. No such effects were found for MIE. Single bouts of HIIT could provide delayed improvements in DTP.

Does aerobic exercise training alter responses to opioid analgesics in individuals with chronic low back pain? A randomized controlled trial

ABSTRACT

We tested whether aerobic exercise training altered morphine analgesic responses or reduced morphine dosages necessary for adequate analgesia. Patients with chronic back pain were randomized to an 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 45). Before and after the intervention, participants underwent 3 laboratory sessions (double-blinded, crossover) to assess effects of saline placebo, i.v. morphine (0.09 mg/kg), and i.v. naloxone (12 mg) on low back pain and evoked heat pain responses. Differences in evoked and back pain measures between the placebo and morphine conditions indexed morphine analgesia, with pre-post intervention changes the primary outcome. Endogenous opioid analgesia was indexed by differences in evoked and low back pain measures between the naloxone and placebo conditions. A Sex X Intervention interaction on the analgesic effects of morphine on visual analogue scale back pain intensity was observed (P = 0.046), with a similar trend for evoked pain threshold (P = 0.093). Male exercisers showed reduced morphine analgesia pre-post intervention, whereas male controls showed increased analgesia (with no differences in females). Of clinical significance were findings that relative to the control group, aerobic exercise produced analgesia more similar to that observed after receiving ≈7 mg morphine preintervention (P < 0.045). Greater pre-post intervention increases in endogenous opioid function (from any source) were significantly associated with larger pre-post intervention decreases in morphine analgesia (P < 0.046). The overall pattern of findings suggests that regular aerobic exercise has limited direct effects on morphine responsiveness, reducing morphine analgesia in males only.

Efficiency of an Optimized Care Organization in Fibromyalgia Patients: The From Intent to Move (FIMOUV) Study Protocol of a Randomized Controlled Trial

Introduction: Fibromyalgia (FM) is characterized by multiple symptoms including pain, fatigue, and sleep disorders, altering patient's quality of life. In the absence of effective pharmacological therapy, the last European guidelines recommend a multidisciplinary management based on exercise and education. Thus, our main objective was to measure the effectiveness of a healthcare organization offering a specific program of adapted physical activity combined with a therapeutic education program for FM patients.

Methods and Analysis: The From Intent To Move (FIMOUV) study will recruit 330 FM patients randomized into two groups: test and control. The test group will benefit from a 1-month mixed exercise training program supervised at the hospital, followed by 2 months in a community-based relay in a health-sport structure. In addition, each of the two groups will benefit from therapeutic patient education sessions. The main endpoint is the measurement of the level of physical activity by accelerometry at 1 year. The secondary endpoints concern adherence to the practice of physical activity, impact on lifestyle, state of health, and physical capacity, as well as an estimate of the budgetary impact of this management strategy.

Discussion: This interventional research will allow us to assess the evolution of behaviors in physical activity after an FM syndrome management based solely on patient education or based on a supervised and adapted practice of physical activity associated with this same therapeutic education program. It seems to be the first study evaluating the impact of its intervention on objective data for measuring physical activity and sedentary behavior via accelerometry among FM patients.

Trial registration:ClinicalTrials.gov NCT04107948.

Longer leisure walking time is associated with positive self-rated health among adults and older adults: a Brazilian nationwide study

Background

To verify the association between weekly leisure walking time and positive self-rated health in the Brazilian adult and elderly population.

Methods

This cross-sectional study used information collected in 2019 across all regions of Brazil. This study included 25,785 people aged ≥ 18 years (mean = 51.6; standard deviation = 18.0) from all capitals of the Brazilian states who reported practicing walking as physical activity during leisure time. Self-rated health was the dependent variable (positive or negative). The leisure walking time/week was the main exposure and it was categorized in “150 minutes/week”, “150–299 minutes/week” and “≥ 300 minutes/week”. We used binary logistic regression to estimate odds ratio (OR) and 95% confidence intervals (95% CI) that was adjusted for relevant covariates.

Results

We found that individuals who reported leisure walking for a period from 150 to 299 minutes/week and those who reported walking for a period ≥ 300 minutes/week were respectively 28% (OR = 1.28. 95% CI [1.10–1.48]) and 52% (OR = 1.52. 95% CI [1.27–1.82]) more likely of perceiving their health positively compared to those who reported walking for a period < 150 minutes/week. Individuals who reported leisure walking time <150 minutes/week had 72.3% (95% CI [70.4–74.1]) probability of perceiving their health positively. Individuals who reported leisure walking time from 150 to 299 minutes/week had 76.6% (95% CI [75.0 –78.3) probability of perceiving their health positively. On the other hand, individuals who reported leisure walking time ≥ 300 minutes/week had 79.2% probability (95% CI [77.1–81.4]) of perceiving their health positively.

Conclusion

Longer leisure walking time was associated with positive self-rated health among adults and older adults in Brazil.

Are endogenous opioid mechanisms involved in the effects of aerobic exercise training on chronic low back pain? A randomized controlled trial

Aerobic exercise is believed to be an effective chronic low back pain (CLBP) intervention, although its mechanisms remain largely untested. This study evaluated whether endogenous opioid (EO) mechanisms contributed to the analgesic effects of an aerobic exercise intervention for CLBP. Individuals with CLBP were randomized to a 6-week, 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 44). Before and after the intervention, participants underwent separate laboratory sessions to assess responses to evoked heat pain after receiving saline placebo or intravenous naloxone (opioid antagonist) in a double-blinded, crossover fashion. Chronic pain intensity and interference were assessed before and after the intervention. Endogenous opioid analgesia was indexed by naloxone-placebo condition differences in evoked pain responses (blockade effects). Relative to controls, exercise participants reported significantly greater pre-post intervention decreases in chronic pain intensity and interference (Ps < 0.04) and larger reductions in placebo condition evoked pain responsiveness (McGill Pain Questionnaire-Short Form [MPQ]-Total). At the group level, EO analgesia (MPQ-Total blockade effects) increased significantly pre-post intervention only among female exercisers (P = 0.03). Dose-response effects were suggested by a significant positive association in the exercise group between exercise intensity (based on meeting heart rate targets) and EO increases (MPQ-Present Pain Intensity; P = 0.04). Enhanced EO analgesia (MPQ-Total) was associated with a significantly greater improvement in average chronic pain intensity (P = 0.009). Aerobic exercise training in the absence of other interventions appears effective for CLBP management. Aerobic exercise-related enhancements in endogenous pain inhibition, in part EO-related, likely contribute to these benefits.

Diet-induced prediabetes: effects of exercise treatment on risk factors for cardiovascular complications

BACKGROUND

An animal model of prediabetes that has been developed in our laboratory using a high fat high carbohydrate diet and lack of physical activity displays risk factors for cardiovascular complications. The effect of exercise against these risk factors in this animal model remains unknown. Therefore, we evaluated the effect of intermittent and regular exercise treatment on the risk factors for cardiovascular complications in this animal model of prediabetes.

METHODS

Following prediabetes induction, animals were randomly assigned to the following groups (n = 6): non-diabetic, prediabetic, intermittently exercising prediabetic and regularly exercising prediabetic. Exercise exposure was 7 weeks long. Body weight changes, caloric intake, blood glucose, total cholesterol, and triglyceride concentration was measured after 20 and 29 weeks while blood pressure was only measured after 29 weeks. Plasma endothelial nitric oxide synthase, malonaldehyde, glutathione peroxidase, tumour necrosis factor-alpha and C-reactive protein concentration from the heart were measured 2 weeks post-exercise termination (week 30).

RESULTS

We found increased body weight, caloric intake and mean arterial pressure in the prediabetic group by comparison to the non-prediabetic group. The same trend was observed in blood glucose and triglyceride concentrations. However, all of these parameters were reduced in the intermittently exercising prediabetic and regularly exercising prediabetic groups. This reduction was further accompanied by a decrease in the endothelial nitric oxide synthase, tumour necrosis factor-alpha and C-reactive protein concentration with improved oxidative stress biomarkers.

CONCLUSIONS

The progression of pre-diabetes to diabetes is slowed or possibly stopped by exercise (regular or intermittent). Additionally, biomarker profiles indicative of cardiovascular disease in pre-diabetics are improved by exercise.

Exercise-induced euphoria and anxiolysis do not depend on endogenous opioids in humans

A runner's high describes a sense of well-being during endurance exercise characterized by euphoria and anxiolysis. It has been a widespread belief that the release of endogenous opioids, such as endorphins, underlie a runner's high. However, exercise leads to the release of two classes of rewarding molecules, endocannabinoids (eCBs) and opioids. In mice, we have shown that core features of a runner's high depend on cannabinoid receptors but not opioid receptors. In the present study, we aimed to corroborate in humans that endorphins do not play a significant role in the underlying mechanism of a runner's high. Thus, we investigated whether the development of two core features of a runner's high, euphoria and reduced anxiety levels, depend on opioid signaling by using the opioid receptor antagonist naltrexone (NAL) in a double-blind, randomized, placebo (PLA)-controlled experiment. Participants (N = 63) exhibited increased euphoria and decreased anxiety after 45 min of running (RUN) on a treadmill in a moderate-intensity range compared to walking (WALK). RUN led to higher plasma levels of the eCBs anandamide (AEA) and 2-arachidonoglycerol (2-AG). Opioid blockade did not prevent the development of euphoria and reduced anxiety as well as elevation of eCB levels following exercise. Moreover, the fraction of participants reporting a subjective runner's high was comparable in the NAL and PLA-treated group. Therefore, this study indicates that the development of a runner's high does not depend on opioid signaling in humans, but makes eCBs strong candidates in humans, as previously shown in mice.

Review of High-Intensity Interval Training for Cognitive and Mental Health in Youth

PURPOSE

High-intensity interval training (HIIT) has emerged as a time-efficient strategy to improve children's and adolescents' health-related fitness in comparison to traditional training methods. However, little is known regarding the effects on cognitive function and mental health. Therefore, the aim of this systematic review was to evaluate the effect of HIIT on cognitive function (basic information processing, executive function) and mental health (well-being, ill-being) outcomes for children and adolescents.

METHODS

A systematic search was conducted, and studies were eligible if they 1) included a HIIT protocol, 2) examined cognitive function or mental health outcomes, and 3) examined children or adolescents (5-18 yr). Separate meta-analyses were conducted for acute and chronic studies, with potential moderators (i.e., study duration, risk of bias, participant age, cognitive demand, and study population) also explored.

RESULTS

A total of 22 studies were included in the review. In acute studies, small to moderate effects were found for executive function (standardized mean difference [SMD], 0.50, 95% confidence interval [CI], 0.03-0.98; P = 0.038) and affect (SMD, 0.33; 95% CI, 0.05-0.62; P = 0.020), respectively. For chronic studies, small significant effects were found for executive function (SMD, 0.31; 95% CI, 0.15-0.76, P < 0.001), well-being (SMD, 0.22; 95% CI, 0.02-0.41; P = 0.029), and ill-being (SMD, -0.35; 95% CI, -0.68 to -0.03; P = 0.035).

CONCLUSIONS

Our review provides preliminary review evidence suggesting that participation in HIIT can improve cognitive function and mental health in children and adolescents. Because of the small number of studies and large heterogeneity, more high-quality research is needed to confirm these findings.

Seasonal Variation in the Brain μ-Opioid Receptor Availability

Seasonal rhythms influence mood and sociability. The brain μ-opioid receptor (MOR) system modulates a multitude of seasonally varying socioemotional functions, but its seasonal variation remains elusive with no previously reported in vivo evidence. Here, we first conducted a cross-sectional study with previously acquired human [¹¹C]carfentanil PET imaging data (132 male and 72 female healthy subjects) to test whether there is seasonal variation in MOR availability. We then investigated experimentally whether seasonal variation in daylength causally influences brain MOR availability in rats. Rats (six male and three female rats) underwent daylength cycle simulating seasonal changes; control animals (two male and one female rats) were kept under constant daylength. Animals were scanned repeatedly with [¹¹C]carfentanil PET imaging. Seasonally varying daylength had an inverted U-shaped functional relationship with brain MOR availability in humans. Brain regions sensitive to daylength spanned the socioemotional brain circuits, where MOR availability peaked during spring. In rats, MOR availabilities in the brain neocortex, thalamus, and striatum peaked at intermediate daylength. Varying daylength also affected the weight gain and stress hormone levels. We conclude that cerebral MOR availability in humans and rats shows significant seasonal variation, which is predominately associated with seasonal photoperiodic variation. Given the intimate links between MOR signaling and socioemotional behavior, these results suggest that the MOR system might underlie seasonal variation in human mood and social behavior.SIGNIFICANCE STATEMENT Seasonal rhythms influence emotion and sociability. The central μ-opioid receptor (MOR) system modulates numerous seasonally varying socioemotional functions, but its seasonal variation remains elusive. Here we used positron emission tomography to show that MOR levels in both human and rat brains show daylength-dependent seasonal variation. The highest MOR availability was observed at intermediate daylengths. Given the intimate links between MOR signaling and socioemotional behavior, these results suggest that the MOR system might underlie seasonal variation in human mood and social behavior.

Evidence-Based Exercise Recommendations to Improve Mental Wellbeing in Women with Breast Cancer During Active Treatment: A Systematic Review and Meta-Analysis

Breast cancer was the most common cancer in women worldwide. The aims of the current systematic review and meta-analysis are: (i) to systematically examine the effects of exercise interventions on mental wellbeing; (ii) to examine the specific effect of the type of supervised exercise and its intensity, volume and frequency on mental wellbeing; and (iii) to explore which interventions are most effective in mental wellbeing among women with breast cancer during active treatment. An electronic literature search was performed using MEDLINE (via PubMed), Embase (Ovid), and Web of Science, we identified 175 full-text articles. The 57 publications included data from 6988 participants, age ranging from 18 to 78 years (weighted mean: 50.85 years). Compared with the control conditions, exercise training programs were associated with significant reductions in anxiety (d = -0.22, I² = 53.0%), depression (d = -0.24, I² = 66.6%), and fatigue (d = -0.47, I² = 69.8%), as well as increases in body image (d = 0.27, I² = 69.2%) and quality of life (overall, d = 0.46, I² = 71.6%; emotional function, d = 0.33, I² = 65.7%; and FACT-B, d = 0.60, I² = 76.2%). There were a variety of frequencies, intensities, and durations of supervised exercise programs reported in the included meta-analytic approach. In addition, we found that concomitant concurrent training, at moderate-to-vigorous intensity, and with a volume ≥50 min/week had benefits on a number of health outcomes, such as fatigue, depression, and quality of life measure by the FACT-B instrument. These findings have important implications for healthcare providers and multidisciplinary teams involved in mental health management in cancer patients during active treatment.

High-intensity interval training in the prehabilitation of cancer patients-a systematic review and meta-analysis

PURPOSE

To evaluate the impact of high-intensity interval training (HIIT) on health-related outcome parameters in the prehabilitation of patients diagnosed with cancer.

METHODS

A systematic review and meta-analysis of comparative studies on HIIT in cancer prehabilitation conducted by screening standard databases from their inception to March 30, 2020. Outcomes of interest included cardiorespiratory fitness, feasibility, safety, clinical, and patient-reported outcomes.

RESULTS

Of the 855 identified studies, 8 articles met the inclusion criteria (7 randomized, 1 non-randomized controlled trial) with a total of 896 patients. The study protocols were heterogeneous, but the methodological quality ranged from good to high according to PEDro scale. Meta-analysis revealed a significant improvement of peak oxygen consumption (VO₂peak) achieved with HIIT compared to usual care. Furthermore, HIIT was feasible and safe, showing low risk of adverse events and positive effects on health-related outcomes in prehabilitative settings.

CONCLUSION

In the phase of prehabilitation, HIIT has potential health benefits in patients diagnosed with cancer and is feasible and safe to perform. Nonetheless, larger randomized controlled trials focusing on long-term effects (such as cancer recurrence or survival rates) are missing, to underline the potential relevance of HIIT for cancer patients.

β-endorphin response to aerobic and anaerobic exercises in Wistar male rats

BACKGROUND Physical exercise is strongly associated with the release of β-endorphin. It is assumed that the type and intensity of physical exercise contributes to the release of β-endorphin. This study aimed to compare levels of β-endorphin in brain tissue in response to aerobic and anaerobic physical exercise. METHODS This study was an experimental laboratory study using 35 male Wistar rats divided into one control group and two physical exercise treatment groups: aerobic and anaerobic. Physical exercise was conducted on an animal treadmill running at aspeed of 20 m/min for 30 min of aerobic exercise and 35 m/min with 1-min intervals every 5 min for 20 min for anaerobic exercises. Each aerobic and anaerobic exercise group was furtherly classified into three subgroups (1×/week, 3×/week, and 7×/week). β-endorphin levels were determined using enzyme-linked immunosorbent assay. The data were analyzed using independent t-test and one-way analysis of variance. RESULTS The highest mean of β-endorphin level was found in the weekly exercise (54.45 [1.41] pg/ml) of aerobic exercise group and daily exercise (70.50 [11.67] pg/ml) of anaerobic exercise group. Mean of β-endorphin level in control group was 33.34 (3.54) pg/ml. A significant increased of β-endorphin mean level (p<0.001) was found in all aerobic and anaerobic exercise groups except the aerobic exercise 7×/week group(37.37 [6.30] pg/ml) compared to control. CONCLUSIONS Both aerobic and anaerobic physical exercise conducted for 6 weeks could increase the level of β-endorphin in brain tissue.

Lowered endogenous mu-opioid receptor availability in subclinical depression and anxiety

Major depressive disorder is associated with lowered mood, anxiety, anhedonia, sleep problems, and cognitive impairments. Many of these functions are regulated by μ-opioid receptor (MOR) system. Preclinical, in vivo, and post-mortem studies have however yielded inconclusive results regarding the role of the MOR in depression and anxiety. Moreover, it is not known whether alterations in MOR are already present in subclinical depression and anxiety. In a large-scale retrospective cross-sectional study we pooled data from 135 (113 males and 22 females) healthy subjects whose brain's MOR availability was measured with positron emission tomography (PET) using an agonist radioligand [11C]carfentanil that has high affinity for MORs. Depressive and anxious symptomology was addressed with BDI-II and STAI-X questionnaires, respectively. Both anxiety and depression scores in the subclinical range were negatively associated with MOR availability in cortical and subcortical areas, notably in amygdala, hippocampus, ventral striatum, and orbitofrontal and cingulate cortices. We conclude that dysregulated MOR availability is involved in altered mood and pathophysiology of depression and anxiety disorders.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Blunted endogenous opioid release following an oral dexamphetamine challenge in abstinent alcohol-dependent individuals

Addiction has been proposed as a 'reward deficient' state, which is compensated for with substance use. There is growing evidence of dysregulation in the opioid system, which plays a key role in reward, underpinning addiction. Low levels of endogenous opioids are implicated in vulnerability for developing alcohol dependence (AD) and high mu-opioid receptor (MOR) availability in early abstinence is associated with greater craving. This high MOR availability is proposed to be the target of opioid antagonist medication to prevent relapse. However, changes in endogenous opioid tone in AD are poorly characterised and are important to understand as opioid antagonists do not help everyone with AD. We used [11C]carfentanil, a selective MOR agonist positron emission tomography (PET) radioligand, to investigate endogenous opioid tone in AD for the first time. We recruited 13 abstinent male AD and 15 control participants who underwent two [11C]carfentanil PET scans, one before and one 3 h following a 0.5 mg/kg oral dose of dexamphetamine to measure baseline MOR availability and endogenous opioid release. We found significantly blunted dexamphetamine-induced opioid release in 5 out of 10 regions-of-interest including insula, frontal lobe and putamen in AD compared with controls, but no significantly higher MOR availability AD participants compared with HC in any region. This study is comparable to our previous results of blunted dexamphetamine-induced opioid release in gambling disorder, suggesting that this dysregulation in opioid tone is common to both behavioural and substance addictions.

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.

One-Week High-Intensity Interval Training Increases Hippocampal Plasticity and Mitochondrial Content without Changes in Redox State

Evidence suggests that physical exercise has effects on neuronal plasticity as well as overall brain health. This effect has been linked to exercise capacity in modulating the antioxidant status, when the oxidative stress is usually linked to the neuronal damage. Although high-intensity interval training (HIIT) is the training-trend worldwide, its effect on brain function is still unclear. Thus, we aimed to assess the neuroplasticity, mitochondrial, and redox status after one-week HIIT training. Male (C57Bl/6) mice were assigned to non-trained or HIIT groups. The HIIT protocol consisted of three days with short bouts at 130% of maximum speed (Vmax), intercalated with moderate-intensity continuous exercise sessions of 30 min at 60% Vmax. The mass spectrometry analyses showed that one-week of HIIT increased minichromosome maintenance complex component 2 (MCM2), brain derived neutrophic factor (BDNF), doublecortin (DCX) and voltage-dependent anion-selective channel protein 2 (VDAC), and decreased mitochondrial superoxide dismutase 2 (SOD 2) in the hippocampus. In addition, one-week of HIIT promoted no changes in H₂O₂ production and carbonylated protein concentration in the hippocampus as well as in superoxide anion production in the dentate gyrus. In conclusion, our one-week HIIT protocol increased neuroplasticity and mitochondrial content regardless of changes in redox status, adding new insights into the neuronal modulation induced by new training models.

Interindividual variability and lateralization of μ-opioid receptors in the human brain

Alterations in the brain's μ-opioid receptor (MOR) system have been associated with several neuropsychiatric disorders. Central MOR availability also varies considerably in healthy individuals. Multiple epidemiological factors have been proposed to influence the MOR system, but due to small sample sizes the magnitude of their influence remains inconclusive. We compiled [¹¹C]carfentanil positron emission tomography scans from 204 individuals with no neurologic or psychiatric disorders, and estimated the effects of sex, age, body mass index (BMI) and smoking on [¹¹C]carfentanil binding potential using between-subject regression analysis. We also examined hemispheric differences in MOR availability. Older age was associated with increase in MOR availability in frontotemporal areas but decrease in amygdala, thalamus, and nucleus accumbens. The age-dependent increase was stronger in males. MOR availability was globally lowered in smokers but independent of BMI. Finally, MOR availability was higher in the right versus the left hemisphere. The presently observed variation in MOR availability may explain why some individuals are prone to develop MOR-linked pathological states, such as chronic pain or psychiatric disorders. Lateralized MOR system may reflect hemispheric work specialization in central emotion and pain processes.

Affective Modulation after High-Intensity Exercise Is Associated with Prolonged Amygdalar-Insular Functional Connectivity Increase

Acute moderate exercise has been shown to induce prolonged changes in functional connectivity (FC) within affect and reward networks. The influence of different exercise intensities on FC has not yet been explored. Twenty-five male athletes underwent 30 min of “low”- (35% < lactate threshold (LT)) and “high”- (20% > LT) intensity exercise bouts on a treadmill. Resting-state fMRI was acquired at 3 Tesla before and after exercise, together with the Positive and Negative Affect Scale (PANAS). Data of 22 subjects (3 dropouts) were analyzed using the FSL feat pipeline and a seed-to-network-based analysis with the bilateral amygdala as the seed region for determining associated FC changes in the “emotional brain.” Data were analyzed using a repeated measures ANOVA. Comparisons between pre- and post-exercise were analyzed using a one-sample t-test, and a paired t-test was used for the comparison between “low” and “high” exercise conditions (nonparametric randomization approach, results reported at p < 0.05). Both exercise interventions induced significant increases in the PANAS positive affect scale. There was a significant interaction effect of amygdalar FC to the right anterior insula, and this amygdalar-insular FC correlated significantly with the PANAS positive affect scale (r = 0.47, p = 0.048) in the “high”-intensity exercise condition. Our findings suggest that mood changes after exercise are associated with prolonged alterations in amygdalar-insular FC and occur in an exercise intensity-dependent manner.