Short-term high-Intensity interval training increases systemic brain-derived neurotrophic factor (BDNF) in healthy women

A 10 years update of effects of exercise on depression disorders-in otherwise healthy adults: A systematic review of meta-analyses and neurobiological mechanisms

BACKGROUND

Depression is one of the most common mental illnesses worldwide and is a major burden for those affected. As conventional therapies do not always work and are also associated with side effects, alternative treatment methods are urgently indicated. In the past, exercise has established itself as a seemingly good alternative treatment method. The aim of this work is to provide a state of the art review and to check whether there are new findings since the publication of the article by Wegner and colleagues 10 years ago.

METHODS

A systematic literature search was conducted. This included searching for appropriate literature in databases such as PsycINFO, PsychARTICLES, PubMed, CINAHL Complete, SocINDEX, SPORTDiscus and Psyndex. Effect sizes calculation and evaluation of the methodological characteristics (AMSTAR 2) were carried out. Finally, the neurobiological explanations for the effect of exercise on depression are discussed.

RESULTS

Eleven meta-analyses met the inclusion criteria, with the total sample consisting of 16.255 participants and 229 individual studies. The most frequently implemented intervention was aerobic exercise, while the intervention in the control groups was usually no treatment, waiting list, or attention/activity placebo. The pooled results indicate a moderate clinical effect, suggesting the positive effect of exercise and physical activity in reducing depressive symptoms (SMD = -0.61, 95% CI [- 0.78; -0.43], p = <0.01).

CONLCUSION

The medium but consistently positive effects that were found in the present study place exercise/ physical activity as a promising and helpful alternative for adults with depression. The positive effect of exercise and physical activity could potentially be explained by neurological changes. However, the exact mechanisms underlying the antidepressant effects are still unclear.

Acute effects of high-intensity interval exercise plus whole-body vibration on bone turnover markers, BDNF, irisin, and neurocognitive performance in postmenopausal women

The acute effects of exercise can elucidate the molecular and psychophysiological mechanisms underlying exercise's benefits in several systems (e.g., the brain, muscle, and bone). In this study, a single 30-minute session of high-intensity interval aerobic exercise (HIIAE) administered in conjunction with isometric resistance exercise on a whole-body vibration (WBV) platform (HIIAE+WBV) was compared with HIIAE alone in their effects on molecular and neurocognitive indices among 63 sedentary, healthy postmenopausal women who were randomly assigned to HIIAE (n = 20), HIIAE+WBV (n = 20), and Control (n = 23) groups. The assessed molecular indices were serum levels of osteocalcin (OC), uncarboxylated OC (ucOC), carboxylated OC (cOC), brain-derived neurotrophic factor (BDNF), and irisin, and the assessed neurocognitive indices were the accuracy rate (AR), reaction time (RT), and electroencephalography event-related potentials (ERPs) of P2 and P3 components in a visuospatial working memory task. Data on these indices before versus after an acute bout of HIIAE or HIIAE+WBV or after a resting session were compared. An HIIAE or HIIAE+WBV intervention yielded no significant change in ERP P2 latency/amplitude and P3 latency but yielded significantly higher ARs, shorter RTs, larger ERP P3 amplitudes, and higher OC, cOC, BDNF, and irisin levels in the postmenopausal women. HIIAE+WBV outperformed HIIAE alone in AR, ucOC, and BDNF. However, the changes in these molecular and neurocognitive indices induced by the two exercise modes did not show any significant correlations in the present study. The present findings suggest that HIIAE and HIIAE+WBV have the potential to acutely influence markers of bone and brain health, with HIIAE+WBV showing greater effectiveness than HIIAE alone. These interventions should be further investigated in future randomized controlled trials involving postmenopausal women.

Comparative effects of moderate-intensity continuous training and high-intensity interval training on ADHD symptoms and behavioral inhibition in children

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition in children, characterized by inattention, hyperactivity, and impulsivity. Recent studies have investigated the potential role of physical exercise as a complementary intervention to traditional ADHD treatments. This study aimed to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on ADHD symptoms and behavioral inhibition in children diagnosed with ADHD. In a randomized controlled trial, 60 male participants aged 7-10 years were allocated into three groups: control, MICT, and HIIT. The intervention lasted 12 weeks, with the MICT group performing 20 min of running at 70-75% of their individual VO2 max and the HIIT group performing alternating intervals of running at 100% and 50% of their VO2 max for 1 min each. The control group received no exercise intervention. Cognitive and symptomatic assessments were conducted using the Children's Symptom Questionnaire (CIS-4) and go/no-go tasks before and 48 h post-intervention. Both MICT and HIIT demonstrated significant improvements in behavioral components, including attention deficit, hyperactivity, and impulsivity (all P < 0.0001). HIIT showed superior effects on attention deficit compared to MICT (P = 0.008). Both HIIT (P < 0.0001) and MICT (P = 0.028) improved correct responses (CR) in the Go task compared to the control group. HIIT also outperformed the control group in erroneous responses (ER) (P = 0.022) and correct reaction time (P = 0.027) in the Go task. In the No-Go task, HIIT showed superiority over the control group in both CR (P = 0.013) and ER components.

CONCLUSION

This study highlights the comparative efficacy of MICT and HIIT as nonpharmacological interventions for children with ADHD. HIIT, in particular, demonstrated superior benefits for attention deficits, suggesting its potential as a targeted adjunctive treatment. These findings may inform the development of exercise programs to enhance the quality of life and daily functioning of children with ADHD.

WHAT IS KNOWN

• Physical exercise has been explored as a complementary intervention for ADHD, with evidence suggesting its potential to improve symptoms such as inattention, hyperactivity, and impulsivity. • Moderate-intensity continuous training (MICT) has shown positive effects on cognitive and behavioral outcomes in children with ADHD.

WHAT IS NEW

• High-intensity interval training (HIIT) demonstrated superior benefits over MICT in improving attention deficits in children with ADHD. • Both HIIT and MICT significantly improved behavioral inhibition, with HIIT showing additional advantages in reducing erroneous responses and enhancing reaction times in cognitive tasks.

Impact of physical exercise on the regulation of brain-derived neurotrophic factor in people with neurodegenerative diseases

This review explores the impact of physical exercise on brain-derived neurotrophic factor (BDNF) and its relationship with neurodegenerative diseases. The key role of BDNF in maintaining brain health is highlighted, and recent studies are analyzed that indicate an increase in BDNF levels following physical activity, particularly in young adults. Additionally, the interaction between the BDNF Val66Met genetic polymorphism and exercise on cognitive function is examined. The review emphasizes the possibility of exercise as a complementary therapy for neurodegenerative diseases, although further research is required to fully understand its effects.

The Effect of High-Intensity Interval Training (HIIT) on Brain-Derived Neurotrophic Factor Levels (BNDF): A Systematic Review

BACKGROUND/OBJECTIVES

High-intensity interval training (HIIT) alternates short periods of intense exercise with recovery, effectively enhancing cardiorespiratory fitness, endurance, and strength in various populations. Concurrently, brain-derived neurotrophic factor (BDNF) supports neuronal resilience and activity-dependent plasticity, which are vital for learning and memory. This study aims to systematically review changes in BDNF levels in response to HIIT, with three primary objectives: evaluating the benefits of HIIT for BDNF modulation, assessing methodological quality and the risk of bias in reviewed studies, and identifying patterns in BDNF response based on HIIT protocols and population characteristics.

METHODS

Comprehensive database searches were conducted in PubMed and SPORTDiscus to identify relevant studies published up to April 2024. Given the diversity in study designs and outcomes, a narrative synthesis was performed rather than a meta-analysis. Bias was evaluated using visualization tools such as RobVis, and the review was conducted by a single researcher, which may limit its comprehensiveness.

RESULTS

Twelve studies met the inclusion criteria, with most indicating significant increases in BDNF levels post-HIIT, suggesting HIIT's potential to enhance neuroplasticity and cognitive functions. However, variations in BDNF responses were observed across different HIIT protocols and study populations. Some studies reported decreases or no change in BDNF levels, reflecting the complex regulation of BDNF influenced by factors such as exercise intensity, duration, and individual variability.

CONCLUSIONS

HIIT shows promise as an intervention for increasing BDNF levels, with potential benefits for brain health and cognitive function. These findings underscore the need for further research to confirm the optimal conditions under which HIIT can effectively enhance neurological outcomes. Future studies should explore standardized HIIT protocols and the long-term impact of HIIT on BDNF and neuroplasticity.

The effect of physical exercise on circulating neurotrophic factors in healthy aged subjects: A meta-analysis and meta-regression

Vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor-1 (IGF-1) may help the brain resist both functional and structural neurodegeneration, which is critical for maintaining cognitive and neurological health in older adults. This meta-analysis and meta-regression seek to elucidate the impact of physical activity on these biomarker levels in healthy seniors, as well as to examine the influence of several moderator factors, including age, sex, period length, and time, for the first time. The standardized mean effect metric was used to assess the influence of weights, which reflected each group's relative importance in comparison to baseline data. The study looked at potential moderating factors including age, gender, and physical activity levels. The analysis of 11 studies indicated no significant effect of physical activity on VEGF levels [0.328, CI 95 % (-0.871 to 1.52); I2 = 0.00; p = 0.592; Q = 4.14]. Physical activity had a substantial impact on brain-derived neurotrophic factor (0.827, 95 % confidence interval: 0.487 to 1.16; I2 = 0.00; p = 0.00; Q = 78.46), with females showing particularly notable effects (Tau2 = 0.327, Tau = 0.571, I2 = 80.90 %, Q = 68.05, df = 15, p = 0.00). Physical activity also had a substantial effect on insulin-like growth factor 1 (0.276, 95 % confidence interval: 0.065 to 0.487; I2 = 0.00; p = 0.10; Q = 8.35), indicating that it positively influences IGF-1 levels. Overall, while physical exercise has a significant effect on BDNF and IGF-1, more research is needed to fully understand its impact on vascular endothelial growth factor and to investigate how individual characteristics may influence exercise outcomes.

Role of Cardiorespiratory Fitness, Aerobic, Exercise and Sports Participation in Female Cognition: A Scoping Review : Sports, Fitness, and Cognition

BACKGROUND

The impact of cardiorespiratory fitness (CRF) on cognition is thought to be mediated by brain-derived neurotrophic factor. Aerobic exercise can increase CRF through various activities, including sports participation. The relationship between these factors in females has yet to be elucidated.

OBJECTIVE

This review aims to map the current literature on the effects of aerobic exercise, sports participation, and CRF in healthy adult females, with sub-topics of pregnancy and menstrual cycle periodicity.

METHODS

A scoping review of the literature was conducted following PRISMA guidelines and the PCC mnemonic (population, concept, and context). The following five databases were screened: CINAHL, Medline, Web of Science, SPORTDiscus, and Scopus. Eligible articles included healthy adult females, investigated aerobic exercise, sports participation or CRF, and linked outcomes to cognition. Data from included manuscripts was extracted and analyzed. Two sub-population groupings (pregnant individuals and menstrual cycle) were established to further aid the interpretation of the findings.

RESULTS

Of the 300 titles and abstracts screened, 74 were eligible for full-text screening, and 28 were included in the scoping review. Of the 28 included, 14 did not control for or report on menstrual cycle phase or sex hormones.

CONCLUSION

This scoping review found an inverse 'U' relationship between aerobic exercise and cognition, demonstrating an optimal dose of aerobic exercise to benefit cognitive functions. As estrogen may impact the relationship between CRF and neural growth factors, more research is needed on this pathway, independent of the menstrual cycle, to determine potential beneficial effects. It is currently unknown whether sports participation can independently impact cognition.

High-intensity interval training ameliorates postnatal immune activation-induced mood disorders through KDM6B-regulated glial activation

Postnatal immune activation (PIA) induces persistent glial activation in the brain and causes various neuropathologies in adults. Exercise training improves stress-related mood disorders; however, the role of exercise in psychiatric disorders induced by early-life immune activation and the association between exercise training and glial activation remain unclear. We compared the effects of different exercise intensities on the PIA model, including high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). Both HIIT and MICT in adolescent mice inhibited neuroinflammation, remodeled synaptic plasticity, and improved PIA-induced mood disorders in adulthood. Importantly, HIIT was superior to MICT in terms of reducing inflammation and increasing body weight. RNA-seq of prefrontal cortex (PFC) tissues revealed a gene expression pattern, confirming that HIIT was more effective than MICT in improving brain glial cell activation through epigenetic modifications of KDM6B. We investigated the role of KDM6B, a specific histone lysine demethylation enzyme - histone 3 lysine 27 demethylase, in inhibiting glial activation against PIA-induced depression and anxiety by regulating the expression of IL-4 and brain-derived neurotrophic factor (BDNF). Overall, our data support the idea that HIIT improves PIA-induced mood disorders by regulating KDM6B-mediated epigenetic mechanisms and indicate that HIIT might be superior to MICT in improving mood disorders with PIA in mice. Our findings provide new insights into the treatment of anxiety and depression disorders.

Effect of high-intensity interval training and moderate-intensity continuous training on cardiovascular risk factors in adolescents: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In recent years, cardiovascular diseases in adolescents have become more serious. High intensity interval training (HIIT) and moderate intensity continuous training (MICT) have been shown to improve cardiovascular diseases in adolescents. Meta-analysis was conducted to compare the effects of HIIT and MICT on cardiovascular risk factors in adolescents.

METHODS

Randomised controlled trials of HIIT and MICT for cardiovascular risk factors in adolescents up to January 2023 were searched using authoritative databases such as CNKI, Web of Science, PubMed, and EBSCO. Data analysis was performed using Review Manage 5.4 and Stata 14.0.

RESULTS

A total of 12 studies involving 468 participants, mean age 15.19±4.35, were included in the study. The findings showed that compared with MICT, HIIT reduced adolescents' body weight (SMD=-0.18, 95 %CI=-0.58, 0.21) and increased maximal oxygen uptake (SMD=0.56, 95 %CI=0.20, 0.93) and high-density lipoprotein (SMD=-0.47, 95 % CI=-1.11, 0.17), and improved systolic blood pressure (SMD=-0.35, 95 %CI=-0.78, 0.09), glucose (SMD=-1.53, 95 %CI=-2.93, -0.13), and insulin (SMD=-0.66, 95 % CI=-1.73, 0.41), p<0.05. HIIT and MICT improved BMI, fat mass, diastolic blood pressure, triglycerides, total cholesterol, and LDL, with no significant difference between these training types.

CONCLUSION

HIIT was better than MICT for improving cardiovascular health in adolescents, with better effects on body weight, BMI, fat mass, systolic blood pressure, diastolic blood pressure, maximal oxygen uptake, triglyceride, total cholesterol, LDL, HDL, glucose, and insulin levels.

Effectiveness of high-intensity interval training on peripheral brain-derived neurotrophic factor in adults: A systematic review and network meta-analysis

BACKGROUND

High-intensity interval training (HIIT) has emerged as an alternative training method to increase brain-derived neurotrophic factor (BDNF) levels, a crucial molecule involved in plastic brain changes. Its effect compared to moderate-intensity continuous training (MICT) is controversial. We aimed to estimate, and to comparatively evaluate, the acute and chronic effects on peripheral BDNF levels after a HIIT, MICT intervention or a control condition in adults.

METHODS

The CINAHL, Cochrane, PubMed, PEDro, Scopus, SPORTDiscus, and Web of Science databases were searched for randomized controlled trials (RCTs) from inception to June 30, 2023. A network meta-analysis was performed to assess the acute and chronic effects of HIIT versus control condition, HIIT versus MICT and MICT versus control condition on BDNF levels. Pooled standardized mean differences (SMDs) and their 95% confidence intervals (95% CIs) were calculated for RCTs using a random-effects model.

RESULTS

A total of 22 RCTs were selected for the systematic review, with 656 participants (aged 20.4-79 years, 34.0% females) and 20 were selected for the network meta-analysis. Network SMD estimates were significant for HIIT versus control condition (1.49, 95% CI: 0.61, 2.38) and MICT versus control condition (1.08, 95% CI: 0.04, 2.12) for acutely BDNF increase. However, pairwise comparisons only resulted in a significant effect for HIIT versus control condition.

CONCLUSIONS

HIIT is the best training modality for acutely increasing peripheral BDNF levels in adults. HIIT may effectively increase BDNF levels in the long term.

Effect of Resistance Training with Different Set Structures on Neurotrophic Factors and Obesity-Related Biomarkers in Middle-Aged Korean Women with Obesity

This 12-week study investigates the effects of resistance training with different set structures on the plasma levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and obesity-related markers in middle-aged Korean women with obesity. A total of 40 middle-aged women with obesity (mean age, 59.87 ± 2.80 years) were enrolled in this study; only 31 women were able to complete the 12-week exercise period. The participants were randomly divided into the following four groups: control (CON, n = 8), drop set system (Drop, n = 8), descending set system (Descend, n = 7), and ascending set system (Ascend, n = 8). Body composition was recorded, and blood samples were obtained and evaluated before and after the 12-week exercise period intervention. Two groups showed no significant differences in body weight, body fat percentage, and body mass index before and after the 12-week exercise period. However, significant differences were observed in the blood levels of BDNF, NGF, adiponectin, leptin, and glucagon-like peptide-1 (GLP-1). BDNF and NGF showed significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop group had higher BDNF and NFG levels than those of the Ascend and CON groups, while there was a significant increase in the levels of these biomarkers in the Descend and Drop groups in the time comparison. Adiponectin levels also showed significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop and Descend groups had higher adiponectin levels than those of the CON group. Leptin levels decreased significantly in the Descend and Drop groups over time. GLP-1 levels showed no significant differences between the groups; however, there were significant differences in both time and interaction effects. Post hoc analysis revealed that the Drop group had lower GLP-1 levels than those of the CON group. This study suggests that resistance training with different set structures can have varying effects on the blood levels of different biomarkers in middle-aged women with obesity. These findings have implications for exercise prescription, and may provide insights into the mechanisms underlying the beneficial outcomes of resistance training in middle-aged Korean women with obesity.

Genetic insights into the causal relationship between physical activity and cognitive functioning

Physical activity and cognitive functioning are strongly intertwined. However, the causal relationships underlying this association are still unclear. Physical activity can enhance brain functions, but healthy cognition may also promote engagement in physical activity. Here, we assessed the bidirectional relationships between physical activity and general cognitive functioning using Latent Heritable Confounder Mendelian Randomization (LHC-MR). Association data were drawn from two large-scale genome-wide association studies (UK Biobank and COGENT) on accelerometer-measured moderate, vigorous, and average physical activity (N = 91,084) and cognitive functioning (N = 257,841). After Bonferroni correction, we observed significant LHC-MR associations suggesting that increased fraction of both moderate (b = 0.32, CI95% = [0.17,0.47], P = 2.89e - 05) and vigorous physical activity (b = 0.22, CI95% = [0.06,0.37], P = 0.007) lead to increased cognitive functioning. In contrast, we found no evidence of a causal effect of average physical activity on cognitive functioning, and no evidence of a reverse causal effect (cognitive functioning on any physical activity measures). These findings provide new evidence supporting a beneficial role of moderate and vigorous physical activity (MVPA) on cognitive functioning.

Influence of High-Intensity Interval Training on IGF-1 Response, Brain Executive Function, Physical Fitness and Quality of Life in Sedentary Young University Women-Protocol for a Randomized Controlled Trial

Sedentary lifestyles have become a social problem, mainly among women. A sedentary lifestyle has been associated with poorer health in this population, negatively affecting physical and mental health. Physical exercise, in particular high-intensity interval training (HIIT), has been shown to be a neuroprotective tool. The present study provides a protocol design for a parallel-group Randomized Controlled Trial (RCT), whose aim will be to compare the effect of two physical interventions, HIIT and physical activity (increasing daily steps), on Insulin Growth Factor-1 (saliva IGF-1 concentrations), executive functions, quality of life, body composition, physical fitness, and physical activity in young sedentary women. At least 77 women will be recruited and randomly assigned to either a HIIT group (12-week exercise HIIT intervention, 3 sessions/week), the HIIT + PA group (12-week exercise HIIT intervention, 3 sessions/week, plus 10,000 steps/day), or a control group (usual care). The primary outcome measure will the chronic change in IGF-1 concentration levels measured in saliva. Secondary outcome measures will be: (i) executive functions; (ii) body composition; (iii) physical fitness; (iv) physical activity; and (v) quality of life. All outcomes will be assessed at the beginning of the study, after the intervention, and after three months of follow-up. After this intervention, we will be able to determine whether HIIT together with increased physical activity could be more effective than HIIT alone in IGF-1 stimulation. Furthermore, by comparing both intervention groups, we will be able to determine the differential effects on numerous health-related variables. Consequently, the conclusions of this study could help better understand the effects of a training program on IGF-1 concentration levels and executive functions. In addition, various strategies could be proposed through physical exercise to improve cognition in this age group, as well as to improve the health status of this sedentary population.

The Effect of High-Intensity Interval Training Type on Body Fat Percentage, Fat and Fat-Free Mass: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

This systematic review and meta-analysis of randomized controlled trials (RCTs) compared body compositional changes, including fat mass (FM), body fat percentage (BF%), and fat-free mass (FFM), between different types of high-intensity interval training (HIIT) (cycling vs. overground running vs. treadmill running) as well as to a control (i.e., no exercise) condition. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCTs. Thirty-six RCTs lasting between 3 to 15 weeks were included in the current systematic review and meta-analysis. RCTs that examined the effect of HIIT type on FM, BF%, and FFM were sourced from online databases including PubMed, Scopus, Web of Science, and Google Scholar up to 21 June 2022. HIIT (all modalities combined) induced a significant reduction in FM (weighted mean difference [WMD]: −1.86 kg, 95% CI: −2.55 to −1.18, p = 0.001) despite a medium between-study heterogeneity (I2 = 63.3, p = 0.001). Subgroup analyses revealed cycling and overground running reduced FM (WMD: −1.72 kg, 95% CI: −2.41 to −1.30, p = 0.001 and WMD: −4.25 kg, 95% CI: −5.90 to −2.61, p = 0.001, respectively); however, there was no change with treadmill running (WMD: −1.10 kg, 95% CI: −2.82 to 0.62, p = 0.210). There was a significant reduction in BF% with HIIT (all modalities combined) compared to control (WMD: −1.53%, 95% CI: −2.13, −0.92, p = 0.001). All forms of HIIT also decreased BF%; however, overground running induced the largest overall effect (WMD: −2.80%, 95% CI: −3.89 to −1.71, p = 0.001). All types of HIIT combined also induced an overall significant improvement in FFM (WMD: 0.51 kg, 95% CI: 0.06 to 0.95, p = 0.025); however, only cycling interventions resulted in a significant increase in FFM compared to other exercise modalities (WMD: 0.63 kg, 95% CI: 0.17 to 1.09, p = 0.007). Additional subgroup analyses suggest that training for more than 8 weeks, at least 3 sessions per week, with work intervals less than 60 s duration and separated by ≤90 s active recovery are more effective for eliciting favorable body composition changes. Results from this meta-analysis demonstrate favorable body composition outcomes following HIIT (all modalities combined) with overall reductions in BF% and FM and improved FFM observed. Overall, cycling-based HIIT may confer the greatest effects on body composition due to its ability to reduce BF% and FM while increasing FFM.

The impact of aerobic and resistance training intensity on markers of neuroplasticity in health and disease

OBJECTIVE

To determine the effects of low- vs. high-intensity aerobic and resistance training on motor and cognitive function, brain activation, brain structure, and neurochemical markers of neuroplasticity and the association thereof in healthy young and older adults and in patients with multiple sclerosis, Parkinson's disease, and stroke.

DESIGN

Systematic review and robust variance estimation meta-analysis with meta-regression.

DATA SOURCES

Systematic search of MEDLINE, Web of Science, and CINAHL databases.

RESULTS

Fifty studies with 60 intervention arms and 2283 in-analyses participants were included. Due to the low number of studies, the three patient groups were combined and analyzed as a single group. Overall, low- (g=0.19, p = 0.024) and high-intensity exercise (g=0.40, p = 0.001) improved neuroplasticity. Exercise intensity scaled with neuroplasticity only in healthy young adults but not in healthy older adults or patient groups. Exercise-induced improvements in neuroplasticity were associated with changes in motor but not cognitive outcomes.

CONCLUSION

Exercise intensity is an important variable to dose and individualize the exercise stimulus for healthy young individuals but not necessarily for healthy older adults and neurological patients. This conclusion warrants caution because studies are needed that directly compare the effects of low- vs. high-intensity exercise on neuroplasticity to determine if such changes are mechanistically and incrementally linked to improved cognition and motor function.

Immediate effect of high-intensity exercise on brain-derived neurotrophic factor in healthy young adults: A systematic review and meta-analysis

BACKGROUND

Although brain-derived neurotrophic factor (BDNF) has been identified as a molecular biomarker of the neurophysiological effects induced by exercise, the acute effects of high-intensity exercise (HIE) on BDNF levels are inconclusive. This study aims to estimate the immediate effects of HIE on BDNF levels in healthy young adults.

METHODS

A systematic search was conducted in the MEDLINE, Scopus, Cochrane CENTRAL, and SPORTDiscuss databases up to December 2020. Randomized controlled trials (RCTs) and non-RCTs reporting pre-post changes in serum or plasma BDNF after an acute intervention of HIE compared to a control condition were included. Pooled effect sizes (p-ESs) and 95% confidence intervals (95%CIs) were calculated for RCTs using a random effects model with Stata/SE (Version 15.0; StataCorp., College Station, TX, USA). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. PROPERO registration number: CRD42020221047.

RESULTS

A total of 22 studies with 552 individuals (age range: 20-31 years; 59.1% male) were included. The meta-analysis included 10 RCTs that reported valid outcome data. Higher BDNF levels were observed when HIE interventions were compared with non-exercise (p-ES = 0.55, 95%CI: 0.12-0.98; I2 = 25.7%; n = 4 studies) and light-intensity exercise (p-ES = 0.78, 95%CI: 0.15-1.40; I2 = 52.4%; n = 3 studies) but not moderate-intensity exercise (p-ES = 0.93, 95%CI: -0.16 to 2.02; I2 = 88.5%; n = 4 studies) conditions.

CONCLUSION

In comparison to non-exercise or light-intensity exercises, an immediate increase in BDNF levels may occur when young adults perform HIE. Given the benefits obtained maximizing circulating BDNF when performing HIE and its potential effects on brain health, our findings suggest that HIE could be recommended by clinicians as a useful exercise strategy to healthy adults.

The effect of physical exercise on circulating brain-derived neurotrophic factor in healthy subjects: A meta-analysis of randomized controlled trials

OBJECTIVE

To investigate how physical exercise (PE) would affect brain-derived neurotrophic factor (BDNF) in randomized controlled trials (RCTs) of healthy subjects.

METHODS

Seven databases (PubMed, Web of Science, Cochrane, Embase, PsycINFO, CINAHL, SPORTDiscus) were searched for RCTs assessing the effects of PE on serum and/or plasma BDNF until December 18, 2021. Meta-analysis was performed by random-effects method with standardized mean difference (SMD) and 95% confidence intervals (CIs). Subgroup analysis and meta-regression analysis were conducted to investigate the potential source of heterogeneity. Trim and fill method, and leave-one-out cross-validation were conducted.

RESULTS

Eventually, 21 articles, involving 809 participants, were included in the meta-analysis. Overall, both acute (5 trials, SMD: 1.20, 95% CI: 0.36 to 2.04, p = .005) and long-term (17 trials, SMD: 0.68, 95% CI: 0.27 to 1.08, p = .001) PE had significant positive effects on BDNF levels. Via subgroup analysis, studies of long-term PE with larger sample sizes, female participants, participants older than 60 years, and aerobic exercise contributed to a more pronounced improvement on BDNF levels than that found when all studies were combined.

CONCLUSION

Both acute and long-term PE had significant positive effects on circulating BDNF in healthy subjects. This review suggests that acute exercise and long-term aerobic exercise are powerful forms of PE to enhance neurotrophic effect, especially for female subjects or subjects over 60 years.

BDNF Impact on Biological Markers of Depression-Role of Physical Exercise and Training

Depression is the most common and devastating psychiatric disorder in the world. Its symptoms, especially during the pandemic, are observed in all age groups. Exercise training (ET) is well known as a non-pharmacological strategy to alleviate clinical depression. The brain-derived neurotrophic factor (BDNF) is one of the biological factors whose expression and secretion are intensified in response to ET. BDNF is also secreted by contracted skeletal muscle that likely exerts para-, auto- and endocrine effects, supporting the crosstalk between skeletal muscle and other distant organs/tissues, such as the nervous system. This finding suggests that they communicate and work together to induce improvements on mood, cognition, and learning processes as BDNF is the main player in the neurogenesis, growth, and survival of neurons. Therefore, BDNF has been recognized as a therapeutic factor in clinical depression, especially in response to ET. The underlying mechanisms through which ET impacts depression are varied. The aim of this review was to provide information of the biological markers of depression such as monoamines, tryptophan, endocannabinoids, markers of inflammatory processes (oxidative stress and cytokines) stress and sex hormones and their relationship to BDNF. In addition, we reviewed the effects of ET on BNDF expression and how it impacts depression as well as the potential mechanisms mediating this process, providing a better understanding of underlying ET-related mechanisms in depression.

Effect of four different forms of high intensity training on BDNF response to Wingate and Graded Exercise Test

This study examined the effects of a nine-week intervention of four different high-intensity training modalities [high-intensity functional training (HIFT), high-intensity interval training (HIIT), high-intensity power training (HIPT), and high-intensity endurance training (HIET)] on the resting concentration of brain-derived neurotropic factor (BDNF). In addition, we evaluated the BDNF responses to Graded Exercise Test (GXT) and Wingate Anaerobic Test (WAnT) in men. Thirty-five healthy individuals with body mass index 25.55 ± 2.35 kg/m2 voluntarily participated in this study and were randomly assigned into four training groups. During nine-weeks they completed three exercise sessions per week for one-hour. BDNF was analyzed before and after a GXT and WAnT in two stages: (stage 0-before training and stage 9-after nine weeks of training). At stage 0, an increase in BDNF concentration was observed in HIFT (33%; p < 0.05), HIPT (36%; p < 0.05) and HIIT (38%; p < 0.05) after GXT. Even though HIET showed an increase in BDNF (10%) this was not statistically significant (p > 0.05). At stage 9, higher BDNF levels after GXT were seen only for the HIFT (30%; p < 0.05) and HIIT (18%; p < 0.05) groups. Reduction in BDNF levels were noted after the WAnT in stage 0 for HIFT (- 47%; p < 0.01), HIPT (- 49%; p < 0.001), HIET (- 18%; p < 0.05)], with no changes in the HIIT group (- 2%). At stage 9, BDNF was also reduced after WAnT, although these changes were lower compared to stage 0. The reduced level of BDNF was noted in the HIFT (- 28%; p < 0.05), and HIPT (- 19%;p < 0.05) groups. Additionally, all groups saw an improvement in VO2max (8%; p < 0.001), while BDNF was also correlated with lactate and minute ventilation and selected WAnT parameters. Our research has shown that resting values of BDNF after nine weeks of different forms of high-intensity training (HIT) have not changed or were reduced. Resting BDNF measured at 3th (before GXT at stage 9) and 6th day after long lasting HITs (before WAnT at stage 9) did not differed (before GXT), but in comparison to the resting value before WAnT at the baseline state, was lower in three groups. It appears that BDNF levels after one bout of exercise is depended on duration time, intensity and type of test/exercise.

Peripheral BDNF and psycho-behavioral aspects are positively modulated by high-intensity intermittent exercise and fitness in healthy women

Acute high-intensity intermittent exercise (HIIE) induces the myokine secretion associated with neurogenesis, as well brain-derived neurotrophic factor (BDNF); however, it remains unknown how the menstrual phase influences this secretion after an acute exercise session. The current study aimed to investigate the effects of HIIE performed in luteal and follicular menstrual phases on BDNF, cognitive function, mood, and exercise enjoyment. Fourteen healthy women completed four experimental sessions, randomly. One graded exercise test (GXT) and one HIIE session (10 × 1-min runs 90% peak GXT velocity [1-min recovery]) were performed for each menstrual phase. Blood samples were collected at rest and immediately after efforts, and the profile of mood states questionnaire (POMS) and Stroop-task test were applied. During the HIIE, subjective scales were applied (feeling, felt arousal, rate of perceived exertion, and physical activity enjoyment). The main results showed that the serum BDNF presented no difference between menstrual phases (p = 0.870); however, HIIE increased BDNF concentration in both menstrual phases (p = 0.030). In addition, the magnitude of circulating BDNF variation (Δ%BDNF) and [Formula: see text] demonstrated an inverse relationship in the follicular phase (r =  - 0.539, p = 0.046), whereas in the luteal phase, Δ%BDNF was negatively correlated with time test (r =  - 0.684, p = 0.007) and RPE (r =  - 0.726, p = 0.004) in GXT. No differences between menstrual phases were observed for POMS (p ≥ 0.05); however, HIIE attenuated tension (p < 0.01), depression (p < 0.01), and anger moods (p < 0.01), independently of menstrual phases. The subjective scales and Stroop-task test did not show differences. In conclusion, menstrual cycle phase does not affect serum BDNF levels, cognitive function, mood, and exercise enjoyment. Contrary, HIIE increases peripheral BDNF and attenuates tension, depression, and anger independently of menstrual phase. In addition, Δ%BDNF was correlated with physical fitness in the follicular phase, exhibiting higher changes in women with lower physical fitness status.

Acute Effects of High-Intensity Interval Training on Brain-Derived Neurotrophic Factor, Cortisol and Working Memory in Physical Education College Students

High-intensity interval training (HIIT) is considered one of the most effective methods for improving cardiorespiratory and metabolic functions. However, it is necessary to clarify their effects on neurophysiological responses and coginitive functioning. Thus, this study aimed to determine the effects of an acute bout of HIIT on neurocognitive and stress-related biomarkers and their association with working memory (WM) capacity in healthy young adults. Twenty-five male college students performed a single bout of HIIT consisting of 10 × 1 min of cycling at their VO₂ peak power output. Plasma Brain-Derived Neurotrophic Factor (BDNF) and cortisol (CORT) levels, and WM (Digit Span Test (DST)), were assessed pre-, post- and 30 min post-intervention. Significant post-exercise increases in circulating BDNF and CORT levels were observed coinciding with the highest DST performance; however, no statistical associations were found between cognitive and neurophysiological variables. Moreover, DST scores obtained 30 min after exercise remained higher than those assessed at pre-exercise. In conclusion, the stress induced by a single bout of HIIT induces a remarkable response of BDNF and CORT boosting WM capacity in healthy young males. Future research should clarify the association between cognitive and neurobiological markers during intense exercise stimulation.

HIITing the brain with exercise: mechanisms, consequences and practical recommendations

The increasing number of older adults has seen a corresponding growth in those affected by neurovascular diseases, including stroke and dementia. Since cures are currently unavailable, major efforts in improving brain health need to focus on prevention, with emphasis on modifiable risk factors such as promoting physical activity. Moderate-intensity continuous training (MICT) paradigms have been shown to confer vascular benefits translating into improved musculoskeletal, cardiopulmonary and cerebrovascular function. However, the time commitment associated with MICT is a potential barrier to participation, and high-intensity interval training (HIIT) has since emerged as a more time-efficient mode of exercise that can promote similar if not indeed superior improvements in cardiorespiratory fitness for a given training volume and further promote vascular adaptation. However, randomised controlled trials (RCTs) investigating the impact of HIIT on the brain are surprisingly limited. The present review outlines how the HIIT paradigm has evolved from a historical perspective and describes the established physiological changes including its mechanistic bases. Given the dearth of RCTs, the vascular benefits of MICT are discussed with a focus on the translational neuroprotective benefits including their mechanistic bases that could be further potentiated through HIIT. Safety implications are highlighted and components of an optimal HIIT intervention are discussed including practical recommendations. Finally, statistical effect sizes have been calculated to allow prospective research to be appropriately powered and optimise the potential for detecting treatment effects. Future RCTs that focus on the potential clinical benefits of HIIT are encouraged given the prevalence of cognitive decline in an ever-ageing population.