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Breathing techniques are predicted to affect specific physical and psychological states, such as relaxation or activation, that might benefit physical sport performance (PSP). Techniques include slow-paced breathing (SPB), fast-paced breathing (FBP), voluntary hyperventilation (VH), breath-holding (BH), and alternate- and uni-nostril breathing. A systematic literature search of six electronic databases was conducted in April 2022. Participants included were athletes and exercisers. In total, 37 studies were eligible for inclusion in the systematic review, and 36 were included in the five meta-analyses. Random effects meta-analyses for each breathing technique were computed separately for short-term and longer-term interventions. Results showed that SPB and BH were related to improved PSP, with large and small effect sizes for longer-term interventions, respectively. In short term interventions, SPB, BH, and VH were unrelated to PSP. There was some evidence of publication bias for SPB and BH longer-term interventions, and 41% of the studies were coded as having a high risk of bias. Due to an insufficient number of studies, meta-analyses were not computed for other breathing techniques. Based on the heterogeneity observed in the findings, further research is required to investigate potential moderators and develop standardised breathing technique protocols that might help optimise PSP outcomes.

BackgroundMyokines, released from the contracting muscle, enable communication between the working muscles and other tissue. Their release during physical exercise is assumed to depend on mode, duration, and intensity.ObjectiveThe aim is to examine the acute changes in circulating levels of the myokines IL-6, IL-10, and IL-1ra induced by a bout of resistance exercise and to consider potential moderators of the results.MethodsSystematic literature search was conducted for resistance exercise intervention studies measuring IL-6, IL-10, or IL-1ra before and immediately after resistance exercise in healthy individuals. Random effects meta-analysis was performed for each myokine.ResultsA small to moderate positive effect of resistance exercise for IL-6 and a moderate to large positive effect for IL-1ra were detected. This could not be shown for IL-10. No moderators of the results were detected.ConclusionThis systematic review and meta-analysis clearly showed the immediate positive effects of an acute resistance exercise session on IL-6 and IL-1ra levels.

This article aimed to synthesize the various triggers of the diving response and to perform a meta-analysis assessing their effects on cardiac vagal activity. The protocol was preregistered on PROSPERO (CRD42021231419; 01.07.2021). A systematic and meta-analytic review of cardiac vagal activity was conducted, indexed with the root mean square of successive differences (RMSSD) in the context of the diving response. The search on MEDLINE (via PubMed), Web of Science, ProQuest and PsycNet was finalized on November 6th, 2021. Studies with human participants were considered, measuring RMSSD pre- and during and/or post-exposure to at least one trigger of the diving response. Seventeen papers (n = 311) met inclusion criteria. Triggers examined include face immersion or cooling, SCUBA diving, and total body immersion into water. Compared to resting conditions, a significant moderate to large positive effect was found for RMSSD during exposure (Hedges' g = 0.59, 95% CI 0.36 to 0.82, p .001), but not post-exposure (g = 0.11, 95% CI -0.14 to 0.36, p = .34). Among the considered moderators, total body immersion had a significantly larger effect than forehead cooling (Q

BackgroundRecovery from coronavirus disease 2019 (COVID-19) can be impaired by the persistence of symptoms or new-onset health complications, commonly referred to as Long COVID. In a subset of patients, Long COVID is associated with immune system perturbations of unknown etiology, which could be related to compromised immunoregulatory mechanisms.ObjectiveThe aim of this scoping review was to investigate if regulatory T cell (Treg) dysregulation is observable beyond the acute illness and if it might be involved in Long COVID immunopathology.DesignA systematic search of studies investigating Tregs during COVID-19 convalescence was conducted on MEDLINE (via Pubmed) and Web of Science.ResultsThe literature search yielded 17 relevant studies, of which three included a distinct cohort of patients with Long COVID. The reviewed studies suggest that the Treg population of COVID-19 patients can reconstitute quantitatively and functionally during recovery. However, the comparison between recovered and seronegative controls revealed that an infection-induced dysregulation of the Treg compartment can be sustained for at least several months. The small number of studies investigating Tregs in Long COVID allowed no firm conclusions to be drawn about their involvement in the syndrome’s etiology. Yet, even almost one year post-infection Long COVID patients exhibit significantly altered proportions of Tregs within the CD4+ T cell population.ConclusionsPersistent alterations in cell frequency in Long COVID patients indicate that Treg dysregulation might be linked to immune system-associated sequelae. Future studies should aim to address the association of Treg adaptations with different symptom clusters and blood parameters beyond the sole quantification of cell frequencies while adhering to consensualized phenotyping strategies.

The unique contribution of the serotonin transporter-linked polymorphic region (5-HTTLPR), intronic region 2 (STin2), and monoamine oxidase A (MAO-A) genes to individual differences in personality traits has been widely explored, and research has shown that certain forms of these polymorphisms relate to impulsivity and impulsivity-related disorders. Humans showing these traits are also described as having an asymmetrical prefrontal cortical activity when compared to others. In this explorative study, we examine the relationship between serotonergic neurotransmission polymorphisms, cortical activity features (prefrontal alpha asymmetry, individual alpha peak frequency [iAPF]), emotion-related and non-emotion-related impulsivity in humans. 5-HTTLPR, MAO-A, and STin2 polymorphisms were assessed in blood taken from 91 participants with high emotion-related impulsivity levels. Sixty-seven participants completed resting electroencephalography and a more comprehensive impulsivity index. In univariate analyses, iAPF correlated with both forms of emotion-related impulsivity. In multiple linear regression models, 5-HTTLPR polymorphism (model 1, adj. R2 = 15.2%) and iAPF were significant interacting predictors of emotion-related impulsivity, explaining a large share of the results’ variance (model 2, adj. R2 = 21.2%). Carriers of the low transcriptional activity 5-HTTPLR and MAO-A phenotypes obtained higher emotion-related impulsivity scores than others did. No significant results were detected for non-emotion-related impulsivity or for a form of emotion-related impulsivity involving cognitive/motivational reactivity to emotion. Our findings support an endophenotypic approach to impulsivity, showing that tri-allelic 5-HTTLPR polymorphism, iAPF, and their interaction are relevant predictors of one form of emotion-related impulsivity.

Background Previous findings suggest that impulsivity is related to chronic low-grade inflammation. Inflammation is known to trigger the kynurenine pathway to a pathological level in various impulsivity-related disorders. Nonetheless, murine models and recent human studies have shown that physical exercise, in particular High Intensity Interval Training (HIIT), could counterbalance the negative effects of inflammation on the kynurenine pathway. Aim This study evaluates the effects of eight weeks of HIIT versus an active control group on impulsivity levels and accompanying alterations of inflammatory-mediated changes of the kynurenine pathway in a sample of emotionally impulsive humans. Methods Participants were randomly allocated to either HIIT or stretching conditions (three trainings per week for eight weeks). Fitness level was evaluated via VO2peak values at the beginning at end of the intervention. Kynurenine metabolites, pro-inflammatory cytokines, and impulsivity levels were evaluated at T0, T4, and T8 weeks. Statistical analyses were performed using mixed models. Results Fifty-three participants were included in the modified Intention To Treat analysis (45 finished the intervention). The HIIT group (n = 28) largely increased the aerobic fitness of its participants and produced physiological changes while the stretching group (n = 25) did not. HIIT reduced interleukin 6 levels (small to moderate interaction) and reduced the activity of the neurotoxic branch of the kynurenine pathway (small to moderate interaction for KYNA/QA and KYN/QA) after eight weeks of training while the active control did not change. Both interventions were effective to decrease emotion-related impulsivity, however only the HIIT group decreased participants’ emotion-unrelated levels. Changes in emotion-related and -unrelated impulsivity were moderately correlated to changes in KYNA/KYN. Conclusion This study demonstrated that HIIT was able to switch the kynurenine pathway from its neurotoxic branch to its neuroprotective one. This shift was associated with a decrease in impulsivity. Based on these findings, future work may consider investigating more intensively the effect of HIIT on impulsivity-related disorders.

Background Data on changes in natural killer cell cytolytic activity (NKCA) in response to acute physical exercise are contradictory. Objective The aim of this systematic review, meta-analysis and meta-regression is to (1) examine the effect of acute physical exercise on NKCA, (2) shed more light on the moderating factors, and (3) test the assumption of NKCA suppression subsequent to performing sports. Methods Two comparisons of NKCA were performed: (1) pre- versus post-exercise and (2) pre-exercise versus recovery. Data were acquired through a systematic search of MEDLINE (via PubMed), Scopus, and SportDiscus. Studies were eligible for inclusion if the effect of acute physical exercise was assessed including a passive control group and reporting NKCA prior to and immediately after the trial, and during the first 2 h of recovery. To better explain between-study heterogeneity, a moderator analysis was conducted. Results Pooled estimate from 12 studies reporting 18 effect sizes show that NKCA is largely elevated by acute physical exercise (Hedges’ g = 1.02, 95% CI 0.59–1.46, p p p = 0.71), and the quantitative change in NK-cell count (R2 = 0%, p = 0.55) do not play a significant role. Physical exercise does not affect the level of NKCA after the recovery period (g = 0.06, 95% CI − 0.37 to 0.50, p Conclusions This work provides solid evidence for elevated NKCA through performing sports which returns to baseline during the first 1–2 h of recovery, but not below the pre-exercise values providing counterevidence to the assumption of temporarily reduced NKCA. Remarkably, the functional change in NKCA exists independently from the quantitative change in NK-cell count. PROSPERO registration number: CRD42020134257.

Abstract. Emotion-related impulsivity, defined as the tendency to say or do things that one later regret during periods of heightened emotion, has been tied to a broad range of psychopathologies. Previous work has suggested that emotion-related impulsivity is tied to an impaired function of the serotonergic system. Central serotonin synthesis relies on the intake of the essential amino acid, tryptophan and its ability to pass through the blood brain barrier. Objective: The aim of this study was to determine the association between emotion-related impulsivity and tryptophan intake. Methods: Undergraduate participants (N = 25, 16 women, 9 men) completed a self-rated measure of impulsivity (Three Factor Impulsivity Index, TFI) and daily logs of their food intake and exercise. These data were coded using the software NutriNote to evaluate intakes of tryptophan, large neutral amino acids, vitamins B6/B12, and exercise. Results: Correlational analyses indicated that higher tryptophan intake was associated with significantly lower scores on two out of three subscales of the TFI, Pervasive Influence of Feelings scores r = –.502, p

Seminal work has found a negative association between physical exercise and impulsivity levels in humans. This paper aims to strengthen these findings by evaluating the association between the amount of self-reported physical exercise per week and emotion-related impulsivity whilst considering age and gender as covariates on a large-scale dataset.Participants completed an online self-report questionnaire about emotion-related impulsivity (i.e. Feelings Trigger Action) and exercise-related questions. After quality control, 773 participants were included in the analysis. Correlational analyses and a multiple regression model explaining the emotion-related impulsivity scores via the amount of exercise per week and demographic characteristics (i.e. age and gender) were performed.The number of hours spent exercising per week was significantly inversely correlated with the Feelings Trigger Action score (r = -.131

Regular physical activity and exercise interventions are suspected to have anti-inflammatory effects depending on exercise modality, thereby potentially reducing the risk and progress of several chronic diseases. Alterations in the kynurenine pathway may represent a link between inflammatory responses following acute exercise and chronic anti-inflammatory properties, such as increased levels of regulatory T-cells (Treg). Here, we hypothesize that acute exercise activates the kynurenine pathway and physical fitness is associated with proportions of circulating anti-inflammatory Treg in older healthy women. Nineteen older healthy female participants (55 years (SD: ± 5.6)) completed a cardiopulmonary incremental exercise test (CPET) with spirometry on a bicycle ergometer until exhaustion with maximum oxygen uptake (VO2max) as outcome. Blood samples were taken before (T0) and one minute after (T1) the CPET. Levels of tryptophan, serotonin and kynurenine were determined by enzyme-linked immunosorbent assays. Flow cytometry was used to identify proportions of T-cell subsets. Both, kynurenine (p = 0.003, d = 0.40) and the kynurenine/tryptophan ratio (p = 0.034, d = 0.48) increased significantly after acute exercise. Moreover, participants` VO2max was strongly correlated with Treg levels (p < 0.001, r = 0.689). This is the first study indicating a kynurenine pathway activation following acute exercise in older healthy women. The observed correlation between Treg levels and VO2max emphasizes a potential link between short-term upregulated kynurenine levels and longer-term anti-inflammatory properties of exercise. Future research is needed to clarify to what extend acute exercise-induced activations of the kynurenine pathway contribute to Treg differentiation.

A growing body of research has focused on the differentiation of emotion-related versus non-emotion-related impulsivity, assessed by the Three-Factor Impulsivity (TFI) index. The goal of this study is to develop a German TFI index, and to validate the emotion-related impulsivity subscales against indices of substance abuse, physical or psychological disorder, physical exercise, BMI, and hours of sleep. 395 native-German speakers completed the German TFI index and questions on validity indicators online. Factor analyses supported the three-factor structure, including Pervasive Influence of Feelings, Lack of Follow Through, and Feelings Trigger Action. Correlations between factors were higher than in the original work. Both emotion-related impulsivity subscales correlated significantly with psychological disorder, engagement in and minutes of physical exercise per week. When included in multivariate regression models, the three factors explained 3.1%, and 29.2% of variance in amount of exercise per week and psychological disorder, respectively. In sum, findings indicated that the German TFI index has a robust three-factor structure that showed expected links to validity indicators, and novel effects in relation to physical exercise.

Objective: This cross-sectional questionnaire-based study aims to compare physical activity and nature exposure levels between people living in France and Germany during the lockdown. Furthermore, the secondary aim is to observe the relationship between perceived stress, psychological health, physical activity, and nature exposure in Germany and France during the coronavirus disease 2019 (COVID-19)-related lockdown of April/May 2020.Methods: The study includes 419 participants who have completed the Perceived Stress Scale 10, the World Health Organization Quality of Life-BREF, the Godin-Shephard Leisure-Time Physical Activity Questionnaire, the modified Nature Exposure Scale, and complementary questions related to the lockdown period from April 19 to May 11, 2020. Multiple regression models were constructed to evaluate the relationship of nature exposure and physical exercise with overall stress perception and psychological health in France and Germany when considering a broad range of covariates.Results: Exposure to nature during the lockdown (ηp2 = 0.034, p < 0.001), amount of physical activity ηp2 = 0.014, p < 0.001), and psychological health (ηp2 = 0.041, p < 0.001) were greater in German compared with French participants. Godin Index and Nature Exposure Scale total score were both inversely correlated to stress perception and positively correlated to psychological health. The stress and psychological health regression models explained 10% of the results' variance. Physical activity (Godin Index) was a significant for both models. Nature Exposure Scale total score was a significant predictor only for psychological health. When including all significant covariates, the regression models explained 30.7% for the perceived stress and 42.1% for the psychological health total overall variance.Conclusion: Physical activity and nature exposure are significant predictors of psychological health. Even though both variables are associated with stress perception, only physical activity is a significant predictor of stress perception. Our results suggest that physical activity and nature exposure were key factors to go through the lockdown period in France and Germany.

Background: Cognitive impairment is common, debilitating, and poorly managed in persons with multiple sclerosis (pwMS). Exercise training might have positive effects on cognitive performance in pwMS, yet the overall magnitude, heterogeneity, and potential moderators remain unclear. Objective: This three-level meta-analysis aims to identify the effects of exercise training and those of exercise modalities on global and domain-specific cognitive performance in pwMS. Methods: MEDLINE, PsycInfo, SportDiscus, CENTRAL, and EMBASE were screened for randomized and non-randomized clinical trials from inception to 27 January 2020, yielding 3091 articles. Based on titles and abstracts, 75 articles remained in the selection process. After full-text evaluation, 13 studies were finally selected (PROSPERO pre-registered). Results: The pooled effect of exercise training on the global cognitive performance was null ( g = 0.04, 95% confidence interval (CI): –0.11 to 0.18) and no significant differences were displayed among domains. Heterogeneity within studies was null ([Formula: see text]= 0.0%) and between studies was low ([Formula: see text]= 25.1%). None of the moderators (exercise modalities, age, Expanded Disability Status Scale (EDSS), supervision, cognitive domains) reached significance. However, the exercise volume explained most of the overall heterogeneity (slope = 4.651 × 10−5, [Formula: see text] = 100%, [Formula: see text] = 52.34%). Conclusion: These results do not support the efficacy of exercise training on global or domain-specific cognitive performance in pwMS. Future studies are needed to determine whether higher training dose are beneficial.

Purpose Prolonged periods of intense cognitive activity lead to a state of mental exhaustion. While widespread strategies to recover from mental exhaustion (i.e., watching TV) are non-effective, aerobic exercise seems to be a promising approach. This can be explained by the acute and chronic aerobic exercise-induced benefits on the central nervous system. Methods This study investigated the potential of a single bout of moderate aerobic exercise (65–75% of each participants’ individual V˙O2peak) to recover from experimentally induced mental exhaustion. A randomized controlled trial on healthy adults (N = 99) was conducted. They performed 60 min of a cognitively demanding test battery, in order to induce mental exhaustion. Subsequently, they were randomized to one of three treatments: 30 min of moderate aerobic exercise on a cycle ergometer, 30 min of a simple lower body stretching routine (= active control treatment) or watching a popular sitcom (= passive control treatment). Cognitive flexibility performance, mood, tiredness, restlessness, self-perceived cognitive capacity, and motivation were assessed before and after treatment. Results The empirical results showed that moderate aerobic exercise led to a better recovery for cognitive flexibility (mean difference divided by pooled standard deviation, Cohen's d= 0.737), mood (d= 0.405), tiredness (d= 0.480), self-perceived cognitive capacity (d= 0.214), and motivation (d= 0.524) compared to active control treatment. Moderate aerobic exercise was also more effective than passive control treatment (d= 0.102 - 0.286) with the exemption of tiredness (d= 0.015) and restlessness (d = -0.473). Conclusion In conclusion, this study suggests that a single bout of acute aerobic exercise supports regeneration of cognitive flexibility performance and of subjective well-being. This holds true not just compared to artificial active control treatment but also compared to widespread leisure time activity, namely watching TV.

Regular physical activity and exercise interventions are suspected to have anti-inflammatory effects depending on exercise modality, thereby potentially reducing the risk and progress of several chronic diseases. Alterations in the kynurenine pathway may represent a link between inflammatory responses following acute exercise and chronic anti-inflammatory properties, such as increased levels of regulatory T-cells (T(reg)). Here, we hypothesize that acute exercise activates the kynurenine pathway and physical fitness is associated with proportions of circulating anti-inflammatory T(reg) in older healthy women. Nineteen older healthy female participants (55 years (SD: ± 5.6)) completed a cardiopulmonary incremental exercise test (CPET) with spirometry on a bicycle ergometer until exhaustion with maximum oxygen uptake (VO(2)max) as outcome. Blood samples were taken before (T0) and one minute after (T1) the CPET. Levels of tryptophan, serotonin and kynurenine were determined by enzyme-linked immunosorbent assays. Flow cytometry was used to identify proportions of T-cell subsets. Both, kynurenine (p = 0.003, d = 0.40) and the kynurenine/tryptophan ratio (p = 0.034, d = 0.48) increased significantly after acute exercise. Moreover, participants` VO(2)max was strongly correlated with T(reg) levels (p < 0.001, r = 0.689). This is the first study indicating a kynurenine pathway activation following acute exercise in older healthy women. The observed correlation between T(reg) levels and VO(2)max emphasizes a potential link between short-term upregulated kynurenine levels and longer-term anti-inflammatory properties of exercise. Future research is needed to clarify to what extend acute exercise-induced activations of the kynurenine pathway contribute to T(reg) differentiation.

Background: Acute aerobic exercise leads to positive physiological adaptations within the central nervous system. These findings inspired research on potential cognitive benefits following acute aerobic exercise. The effects of acute aerobic exercise on subsequent cognitive performance, by far, have been the most researched for interference control, a subcomponent of executive function. The results of primary studies on the effects of acute aerobic exercise on subsequent interference control performance are inconsistent. Therefore, we used meta-analytic methods to pool available effect sizes, and to identify covariates that determine the magnitude of exercise-induced interference control benefits. Methods: Medline, PsycINFO, and SPORTDiscus were searched for eligible records. Hedges' g corrected standardized mean difference values (SMDs) were used for analyses. Random-effects weights were used to pool effect sizes. Moderator analyses were conducted using meta-regressions and subgroups analyses. Covariates that were here tested for moderation included parameters of the applied exercise regimen (exercise intensity and exercise duration), characteristics of examined participants (age and fitness), and methodological features of existing research (type of control group, familiarization with test procedure, type of test variable, delay between exercise cessation, and testing). Results: Fifty studies, with data from 2,366 participants, were included in qualitative and quantitative synthesis. A small, significant beneficial effect of acute aerobic exercise on time-dependent measures of interference control was revealed (k = 49, Hedges' g = −0.26, 95%CI: −34 to −0.18). Effect sizes from time-dependent measures of interference control varied widely and heterogeneity reached statistical significance (T2 = 0.0557, I2 = 28.8%). Moderator analyses revealed that higher exercise intensities (vigorous intensity and high-intensity interval training), also participants at younger or older age, and participants who are familiar with the testing procedure prior to the experiment, benefitted most from acute aerobic exercise. However, noticeable heterogeneity remained unexplained within specific subgroups (high-intensity interval training, preadolescent children, and active and supervised control group). Conclusion: Acute aerobic exercise improves subsequent interference control performance. However, the covariates exercise intensity, participants' age, and familiarization with testing procedure determine the magnitude of that effect. Methodological features were not found to influence the magnitude of effects. This dismisses some doubts that exercise induced benefits for interference control performance are scientific artifacts. The fact that large heterogeneity remained unexplained in some subgroups indicates the need for further research on covariates within these subgroups. It should be noted that effect sizes for all analyses were small. © Copyright © 2019 Oberste, Javelle, Sharma, Joisten, Walzik, Bloch and Zimmer.

Background: Physical exercise is suspected to reduce cancer risk and mortality. So far, little is known about the underlying mechanisms. Although limited, murine models represent a promising attempt in order to gain knowledge in this field.Objective: A systematic review and meta-analysis examining various treatment protocols was conducted in order to determine the impact of exercise on tumor growth in rodents.Methods: PubMed, Google scholar and System for information on Gray literature in Europe were screened from inception to October 2017. Risk of bias within individual studies was assessed using the Office of Health Assessment and Translation risk of bias rating tool for human and animal trials. The effect of exercise on tumor growth over and above non-exercise control was pooled using random-effects model. Subgroup analyses were conducted to identify potential moderators.Results: The quality of the included 17 articles ranged between “probably low” and “high risk of bias.” A significant reduction in tumor growth in exercising animals compared to controls was detected (Hedges' g = −0.40; 95% CI −0.66 to −0.14, p < 0.01) with between-study heterogeneity (τ2 = 0.217, I2 = 70.28%, p < 0.001). The heterogeneity was partially explained by three moderators representing the in-between group differences of “maximum daily exercise” R2 = 33% (p < 0.01), “type of cancer administration” R2 = 28% (p < 0.05), and “training initiation” R2 = 27% (p < 0.05).Conclusion: This meta-analysis suggests that physical exercise leads to reduction of tumor size in rodents. Since “maximum daily exercise” was found to have at least modest impact on tumor growth, more clinical trials investigating dose-response relationships are needed.

The increasing demand of space flights requires a profound knowledge of the chronologic reactions of the human body to extreme conditions. Prior studies already have shown the adverse effects of long-term isolation on psycho-physiological well-being. The chronology of the effects and whether short-term isolation periods already lead to similar effects has not been investigated. Therefore, the aim of the current study was to investigate the effects of short-term isolation (30 days) on mood, cognition, cortisol, neurotrophic factors, and brain activity. 16 participants were isolated in the Human Exploration Research Analog at NASA for 30 days. 17 non-isolated control participants were tested simultaneously. On mission days − 5, 7, 14, 28, and + 5, multiple tests including the Positive and Negative Affect Schedule-X and cognitive tests were conducted, and a 5-min resting electroencephalography was recorded. A fasted morning blood drawing was also done. Increased stress was observed via augmented cortisol levels during the isolation period. Activity within the parietal cortex was reduced over time, probably representing a neural adaptation to less external stimuli. Cognitive performance was not affected, but rather enhanced in both groups. No further significant changes in neurotrophic factors BDNF/IGF-1 and mood could be detected. These results suggest that 30 days of isolation do not have a significant impact on brain activity, neurotrophic factors, cognition, or mood, even though stress levels were significantly increased during isolation. Further studies need to address the question as to what extent increased levels of stress do not affect mental functions during isolation periods.

Tryptophan (TRP) is an essential amino acid. Metabolites of TRP have been identified as important mediators in immune regulation and function of the central nervous system. Inflammation strongly stimulates to the breakdown of TRP into Kynurenine (KYN), representing the initial step of the KYN pathway. Recently, exercise interventions have been able to demonstrate a modification of the KYN pathway plausibly by altering inflammation. However, modifications differ between acute and chronic exercise interventions. As such, this review examines the current studies that have investigated the effect of an acute (single bout) or chronic (training) exercise intervention on levels of TRP and KYN in both healthy and diseased populations.