Dynamics of Gut Microbiota and Short-Chain Fatty Acids during a Cycling Grand Tour Are Related to Exercise Performance and Modulated by Dietary Intake.

BACKGROUND: Regular exercise has been described to modify both the diversity and the relative abundance of certain bacterial taxa. To our knowledge, the effect of a cycling stage race, which entails extreme physiological and metabolic demands, on the gut microbiota composition and its metabolic activity has not been analysed. OBJECTIVE: The aim of this cohort study was to analyse the dynamics of faecal microbiota composition and short-chain fatty acids (SCFAs) content of professional cyclists over a Grand Tour and their relationship with performance and dietary intake. METHODS: 16 professional cyclists competing in La Vuelta 2019 were recruited. Faecal samples were collected at four time points: the day before the first stage (A); after 9 stages (B); after 15 stages (C); and on the last stage (D). Faecal microbiota populations and SCFA content were analysed using 16S rRNA sequencing and gas chromatography, respectively. A principal component analysis (PCA) followed by Generalised Estimating Equation (GEE) models were carried out to explore the dynamics of microbiota and SCFAs and their relationship with performance. RESULTS: Bifidobacteriaceae, Coriobacteriaceae, Erysipelotrichaceae, and Sutterellaceae dynamics showed a strong final performance predictive value (r = 0.83, ranking, and r = 0.81, accumulated time). Positive correlations were observed between Coriobacteriaceae with acetate (r = 0.530) and isovalerate (r = 0.664) and between Bifidobacteriaceae with isobutyrate (r = 0.682). No relationship was observed between SCFAs and performance. The abundance of Erysipelotrichaceae at the beginning of La Vuelta was directly related to the previous intake of complex-carbohydrate-rich foods (r = 0.956), while during the competition, the abundance of Bifidobacteriaceae was negatively affected by the intake of simple carbohydrates from supplements (r = -0.650). CONCLUSIONS: An ecological perspective represents more realistically the relationship between gut microbiota composition and performance compared to single-taxon approaches. The composition and periodisation of diet and supplementation during a Grand Tour, particularly carbohydrates, could be designed to modulate gut microbiota composition to allow better performance.

Modulation of microRNAs through Lifestyle Changes in Alzheimer's Disease.

Lifestyle factors, including diet and physical activity (PA), are known beneficial strategies to prevent and delay Alzheimer's disease (AD) development. Recently, microRNAs have emerged as potential biomarkers in multiple diseases, including AD. The aim of this review was to analyze the available information on the modulatory effect of lifestyle on microRNA expression in AD. Few studies have addressed this question, leaving important gaps and limitations: (1) in human studies, only circulating microRNAs were analyzed; (2) in mice studies, microRNA expression was only analyzed in brain tissue; (3) a limited number of microRNAs was analyzed; (4) no human nutritional intervention studies were conducted; and (5) PA interventions in humans and mice were poorly detailed and only included aerobic training. Despite this, some conclusions could be drawn. Circulating levels of let-7g-5p, miR-107, and miR-144-3p were associated with overall diet quality in mild cognitive impairment patients. In silico analysis showed that these microRNAs are implicated in synapse formation, microglia activation, amyloid beta accumulation, and pro-inflammatory pathways, the latter also being targeted by miR-129-5p and miR-192-5p, whose circulating levels are modified by PA in AD patients. PA also modifies miR-132, miR-15b-5p, miR-148b-3p, and miR-130a-5p expression in mice brains, which targets are related to the regulation of neuronal activity, ageing, and pro-inflammatory pathways. This supports the need to further explore lifestyle-related miRNA changes in AD, both as biomarkers and therapeutic targets.

Circulating plasma levels of miR-106b-5p predicts maximal performance in female and male elite kayakers.

Introduction: Plasma miR-106b-5p levels have been described as an exercise performance predictor in male amateur runners, although no information is available about female athletes. The aim of this study was to analyze the predictive value on sports performance of plasma miR-106b-5p levels in elite female and male kayakers at the beginning and at the end of a training macrocycle, as well as the potential underlying molecular mechanisms using an in silico approach. Materials and Methods: Eight elite male (26.2 ± 3.6 years) and seven elite female (17.4 ± 0.5 years) kayakers from the Spanish national team. Two fasting blood samples were collected, starting point of the season (A) and maximum fitness level (B). Circulating plasma levels of miR-106b-5p were analyzed by RT-qPCR. Maximal 500 m performance was recorded at B. Results and Discussion: miR-106b-5p levels had no differences between A and B neither in women nor in men. In men but not in women, miR-106b-5p levels showed a negative significant correlation with performance in B which highlights its predictive value for performance. However, in women, progesterone emerged as a determinant and the ratio miR-106b-5p/progesterone showed a significant negative correlation with performance. In silico analysis reveals potential targets in a number of genes of relevant to exercise. Conclusions: miR-106b-5p emerges as a biomarker of athletic performance in men and in women, if the menstrual cycle is considered. This highlights the need to analyze molecular response to exercise in men and women separately, and considering the stage of the menstrual cycle in women as a relevant factor.

miR-24-3p and Body Mass Index as Type 2 Diabetes Risk Factors in Spanish Women 15 Years after Gestational Diabetes Mellitus Diagnosis.

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance that is diagnosed for the first time during pregnancy. The objective of this study is to know the glucose tolerance status after 15 years of pregnancy in patients diagnosed with gestational diabetes and to assess the long-term effect of GDM on the circulating miRNA profile of these women. To answer these, 30 randomly selected women diagnosed with GDM during 2005-2006 were included in the study, and glucose tolerance was measured using the National Diabetes Data Group criteria. Additionally, four miRNAs (hsa-miR-1-3p, hsa-miR-24-3p, hsa-miR-329-3p, hsa-miR-543) were selected for their analysis in the plasma of women 15 years after the diagnosis of GDM. In our study we discovered that, fifteen years after the diagnosis of GDM, 50% of women have some degree of glucose intolerance directly related to body weight and body mass index during pregnancy. Dysglycemic women also showed a significantly increased level of circulating hsa-miR-24-3p. Thus, we can conclude that initial weight and BMI, together with circulating expression levels of hsa-miR-24-3p, could be good predictors of the future development of dysglycemia in women with a previous diagnosis of GDM.

Differences in the microRNAs Levels of Raw Milk from Dairy Cattle Raised under Extensive or Intensive Production Systems.

Studying microRNA (miRNAs) in certain agri-food products is attractive because (1) they have potential as biomarkers that may allow traceability and authentication of such products; and (2) they may reveal insights into the products' functional potential. The present study evaluated differences in miRNAs levels in fat and cellular fractions of tank milk collected from commercial farms which employ extensive or intensive dairy production systems. We first sequenced miRNAs in three milk samples from each production system, and then validated miRNAs whose levels in the cellular and fat fraction differed significantly between the two production systems. To accomplish this, we used quantitative PCR with both fractions of tank milk samples from another 20 commercial farms. Differences in miRNAs were identified in fat fractions: overall levels of miRNAs, and, specifically, the levels of bta-mir-215, were higher in intensive systems than in extensive systems. Bovine mRNA targets for bta-miR-215 and their pathway analysis were performed. While the causes of these miRNAs differences remain to be elucidated, our results suggest that the type of production system could affect miRNAs levels and potential functionality of agri-food products of animal origin.

Physical exercise shapes the mouse brain epigenome.

OBJECTIVE: To analyze the genome-wide epigenomic and transcriptomic changes induced by long term resistance or endurance training in the hippocampus of wild-type mice. METHODS: We performed whole-genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-seq) of mice hippocampus after 4 weeks of specific training. In addition, we used a novel object recognition test before and after the intervention to determine whether the exercise led to an improvement in cognitive function. RESULTS: Although the majority of DNA methylation changes identified in this study were training-model specific, most were associated with hypomethylation and were enriched in similar histone marks, chromatin states, and transcription factor biding sites. It is worth highlighting the significant association found between the loss of DNA methylation in Tet1 binding sites and gene expression changes, indicating the importance of these epigenomic changes in transcriptional regulation. However, endurance and resistance training activate different gene pathways, those being associated with neuroplasticity in the case of endurance exercise, and interferon response pathways in the case of resistance exercise, which also appears to be associated with improved learning and memory functions. CONCLUSIONS: Our results help both understand the molecular mechanisms by which different exercise models exert beneficial effects for brain health and provide new potential therapeutic targets for future research.

Exercise-Induced Hyperhomocysteinemia Is Not Related to Oxidative Damage or Impaired Vascular Function in Amateur Middle-Aged Runners under Controlled Nutritional Intake.

To determine the influence of different doses of maximal acute exercise on the kinetics of plasma homocysteine (tHcy) and its relationship with oxidative status and vascular function, nine recreational runners completed a 10 km race (10K) and a marathon (M). Blood samples were collected before (Basal), immediately post-exercise (Post0), and after 24 h (Post24). Nutritional intake was controlled at each sample point. A significant increase in tHcy was observed after both races, higher after M. Basal levels were recovered at Post24 after 10K, but remained elevated at Post 24 for M. A significant decrease in GSH/GSSG ratio was observed in Post0, especially marked after M. Furthermore, this increase in pro-oxidant status remained at Post24 only after M. Other oxidative status markers failed to confirm this exercise-induced pro-oxidant status except glutathione peroxidase activity that was lower in Post24 compared to Basal in 10K and in Post0 and Post24 in M. No statistical correlation was found between oxidative markers and tHcy. No significant changes were observed in the concentration of endothelial cell adhesion molecules (VCAM-1 and E-Selectin) and VEGF. In conclusion, tHcy increases in an exercise-dose-response fashion but is not related to endothelial dysfunction mediated by oxidative stress mechanisms.

Versatility of Protocols for Resistance Training and Assessment using Static and Dynamic Ladders in Animal Models.

Resistance training is a physical exercise model with profound benefits for health throughout life. The use of resistance exercise animal models is a way to gain insight into the underlying molecular mechanisms that orchestrate these adaptations. The aim of this article is to describe exercise models and training protocols designed for strength training and evaluation of resistance in animal models and provide examples. In this article, strength training and resistance evaluation are based on ladder climbing activity, using static and dynamic ladders. These devices allow a variety of training models as well as provide precise control of the main variables which determine resistance exercise: volume, load, velocity, and frequency. Furthermore, unlike resistance exercise in humans, this is a forced exercise. Thus, aversive stimuli must be avoided in this intervention to preserve animal welfare. Prior to implementation, a detailed design is necessary, along with an acclimatization and learning period. Acclimatization to training devices, such as ladders, weights, and clinical tape, as well as to the manipulations required, is necessary to avoid exercise rejection and to minimize stress. At the same time, the animals are taught to climb up the ladder, not down, to the resting area on the top of the ladder. Resistance evaluation can characterize physical strength and permit adjusting and quantifying the training load and the response to training. Furthermore, different types of strength can be evaluated. Regarding training programs, with appropriate design and device use, they can be sufficiently versatile to modulate different types of strength. Furthermore, they should be flexible enough to be modified depending on the adaptive and behavioral response of the animals or the presence of injuries. In conclusion, resistance training and assessment using ladders and weights are versatile methods in animal research.

Resistance and Endurance Exercise Training Induce Differential Changes in Gut Microbiota Composition in Murine Models.

Background: The effect of resistance training on gut microbiota composition has not been explored, despite the evidence about endurance exercise. The aim of this study was to compare the effect of resistance and endurance training on gut microbiota composition in mice. Methods: Cecal samples were collected from 26 C57BL/6N mice, divided into three groups: sedentary (CTL), endurance training on a treadmill (END), and resistance training on a vertical ladder (RES). After 2 weeks of adaption, mice were trained for 4 weeks, 5 days/week. Maximal endurance and resistance capacity test were performed before and after training. Genomic DNA was extracted and 16S Ribosomal RNA sequenced for metagenomics analysis. The percentages for each phylum, class, order, family, or genus/species were obtained using an open-source bioinformatics pipeline. Results: END showed higher diversity and evenness. Significant differences among groups in microbiota composition were only observed at genera and species level. END showed a significantly higher relative abundance of Desulfovibrio and Desulfovibrio sp., while Clostridium and C. cocleatum where higher for RES. Trained mice showed significantly lower relative abundance of Ruminococcus gnavus and higher of the genus Parabacteroides compared to CTL. We explored the relationship between relative taxa abundance and maximal endurance and resistance capacities after the training period. Lachnospiraceae and Lactobacillaceae families were negatively associated with endurance performance, while several taxa, including Prevotellaceae family, Prevotella genus, and Akkermansia muciniphila, were positively correlated. About resistance performance, Desulfovibrio sp. was negatively correlated, while Alistipes showed a positive correlation. Conclusion: Resistance and endurance training differentially modify gut microbiota composition in mice, under a high-controlled environment. Interestingly, taxa associated with anti- and proinflammatory responses presented the same pattern after both models of exercise. Furthermore, the abundance of several taxa was differently related to maximal endurance or resistance performance, most of them did not respond to training.

Circulating MicroRNA Profiling Reveals Specific Subsignatures in Response to a Maximal Incremental Exercise Test.

ABSTRACT: Fernández-Sanjurjo, M, Díaz-Martínez, ÁE, Díez-Robles, S, González-González, F, de Gonzalo-Calvo, D, Rabadán, M, Dávalos, A, Fernández-García, B, and Iglesias-Gutiérrez, E. Circulating microRNA profiling reveals specific subsignatures in response to a maximal incremental exercise test. J Strength Cond Res 35(2): 287-291, 2021-Circulating microRNAs (c-miRNAs) have been described as emergent regulators and biomarkers of exercise. The aim of this study was to analyze the c-miRNA response to a maximal incremental exercise test (MIET) and its relationship with markers of exercise response and adaptation. Two blood samples were collected from 9 male amateur runners (31-50 years), before (Pre) and after (Post) a MIET. The maximal oxygen uptake (V̇o2max), maximum heart rate (HRmax), and maximal aerobic speed (MAS) were recorded. Lactate and creatine kinase (CK) plasma concentrations were measured. A panel of 752 miRNAs was analyzed using standardized protocols and relative quantification to Pre. A total of 13 miRNAs were found significantly upregulated at Post. By focusing on the exercise markers that correlate with the expression of these miRNAs, they were clustered into different functional groups or subsignatures. Thus, miR-21-5p, miR-29b-3p, and miR-183-5p showed a strong correlation with HRmax and a validated target signature related to fatty acid metabolism. Furthermore, let-7c-5p, miR-340-5p, miR-425-3p, and miR-629-5p were significantly correlated with CK, and the most significantly enriched pathways for these subsignatures were the Hippo signaling pathway and signaling pathways regulating pluripotency of stem cells. Finally, Pre miR-106b-5p expression showed an inverse association with MAS and Post lactate concentration, which highlights its relevance as biomarker of training status and its predictive value for performance. No significant correlations were observed with V̇o2max. Our results define for the first time specific functional c-miRNA subsignatures, adding novel evidence about their potential regulatory role in exercise response.

Exercise dose affects the circulating microRNA profile in response to acute endurance exercise in male amateur runners.

The systemic response to exercise is dose-dependent and involves a complex gene expression regulation and cross-talk between tissues. This context ARISES the need for analyzing the influence of exercise dose on the profile of circulating microRNAs (c-miRNAs), as emerging posttranscriptional regulators and intercellular communicators. Thus, we hypothesized that different exercise doses will determine specific c-miRNA signatures that will highlight its potential as exercise dose biomarker. Nine active middle-aged males completed a 10-km race (10K), a half-marathon (HM), and a marathon (M). Blood samples were collected immediately before and after races. Plasma RNA was extracted, and a global screening of 752 microRNAs was analyzed using RT-qPCR. Three different c-miRNA profiles were defined according to the three doses. In 10K, 14 c-miRNAs were found to be differentially expressed between pre- and post-exercise, 13 upregulated and 1 downregulated. Regarding HM, 13 c-miRNAs were found to be differentially modulated, in all the cases upregulated. A total of 28 c-miRNAs were found to be differentially expressed in M, 21 overexpressed and 7 repressed after this race. We had also found 3 common c-miRNAs between 10K and M and 2 common c-miRNAs between 10K and HM. In silico analysis supported a close association between exercise dose c-miRNA profiles and cellular pathways linked to energy metabolism and cell cycle. In conclusion, we have observed that different exercise doses induced specific c-miRNA profiles. So, our results point to c-miRNAs as emerging exercise dose biomarkers and as one of regulatory mechanisms modulating the response to endurance exercise.

Autophagy is required for performance adaptive response to resistance training and exercise-induced adult neurogenesis.

Endurance training promotes exercise-induced adaptations in brain, like hippocampal adult neurogenesis and autophagy induction. However, resistance training effect on the autophagy response in the brain has not been much explored. Questions such as whether partial systemic autophagy or the length of training intervention affect this response deserve further attention. Therefore, 8-week-old male wild-type (Wt; n = 36) and systemic autophagy-deficient (atg4b-/- , KO; n = 36) mice were randomly distributed in three training groups, resistance (R), endurance (E), and control (non-trained), and in two training periods, 2 or 14 weeks. R and E maximal tests were evaluated before and after the training period. Forty-eight hours after the end of training program, cerebral cortex, striatum, hippocampus, and cerebellum were extracted for the analysis of autophagy proteins (LC3B-I, LC3B-II, and p62). Additionally, hippocampal adult neurogenesis was determined by doublecortin-positive cells count (DCX+) in brain sections. Our results show that, in contrast to Wt, KO were unable to improve R after both trainings. Autophagy levels in brain areas may be modified by E training only in cerebral cortex of Wt trained for 14 weeks, and in KO trained for 2 weeks. DCX + in Wt increased in R and E after both periods of training, with R for 14 weeks more effective than E. Interestingly, no changes in DCX + were observed in KO after 2 weeks, being even undetectable after 14 weeks of intervention. Thus, autophagy is crucial for R performance and for exercise-induced adult neurogenesis.

Circulating microRNAs as emerging cardiac biomarkers responsive to acute exercise.

BACKGROUND: Circulating microRNAs (c-miRNAs) are mediators of intercellular communication with great potential as cardiac biomarkers. The analysis of c-miRNAs in response to physiological stress, such as exercise, would provide valuable information for clinical practice and a deeper understanding of the molecular response to physical activity. Here, we analysed for the first time the acute exercise response of c-miRNAs reported as biomarkers of cardiac disease in a well-characterized cohort of healthy active adults. METHODS: Blood samples were collected immediately before and after (0 h, 24 h, 72 h) a 10-km race, a half-marathon (HM) and a marathon (M). Serum RNA from 10-km and M samples was extracted and a panel of 74 miRNAs analysed using RT-qPCR. c-miRNA response was compared with a panel of nine cardiac biomarkers. Functional enrichment analysis was performed. Pre- and post-M echocardiographic analyses were carried out. RESULTS: Serum levels of all cardiac biomarkers were upregulated in a dose-dependent manner in response to exercise, even in the absence of symptoms or signs of cardiac injury. A deregulation in the profiles of 5 and 19 c-miRNAs was observed for 10-km and M, respectively. Each race induced a specific qualitative and quantitative alteration of c-miRNAs implicated in cardiac adaptions. Supporting their discriminative potential, a number of c-miRNAs previously associated with cardiac disease were undetectable or stable in response to exercise. Conversely, "pseudo-disease" signatures were also observed. CONCLUSIONS: c-miRNAs may be useful for the management of cardiac conditions in the context of acute aerobic exercise. TRANSLATIONAL ASPECTS OF THE WORK: Circulating microRNAs could offer incremental diagnostic value to established and emerging cardiac biomarkers, such as hs-cTnT or NT-proBNP, in those patients with cardiac dysfunction symptoms after an acute bout of endurance exercise. Furthermore, circulating miRNAs could also show "pseudo-disease" signatures in response to acute exercise. Clinical practitioners should be aware of the impact caused by exercise in the interpretation of miRNA data.

Circulating microRNA as Emerging Biomarkers of Exercise.

An interest has recently emerged in the role of circulating microRNAs (c-miRNAs) as posttranscriptional regulators, intercellular communicators and, especially, as potential biomarkers of the systemic response to acute exercise and training. We propose that, with the limited, heterogeneous, and mainly descriptive information currently available, c-miRNAs do not provide a reliable biomarker of exercise in healthy or diseased individuals.

MicroRNA circulantes como reguladores de la respuesta molecular al ejercicio en personas sanas / Circulating microRNA as regulators of the molecular response in exercise in healthy people

Los microRNAs circulantes (c-miRNAs) son reguladores de la expresión génica y mediadores de la comunicación intercelular, con un gran potencial como coordinadores de la respuesta molecular al ejercicio y, por tanto, con eventuales implicaciones prácticas para la salud y el rendimiento. Sin embargo, su respuesta al ejercicio agudo y al entrenamiento en personas sanas es poco conocida, principalmente porque hasta el momento se ha publicado un número reducido de artículos, con resultados dispares. El objetivo de esta revisión es agrupar y sintetizar el conocimiento disponible, analizar las causas de esta heterogeneidad en los resultados e identificar las principales perspectivas de futuro en esta área. Los resultados de los trabajos incluidos en esta revisión muestran que el ejercicio agudo y el entrenamiento inducen una respuesta en el perfil de c-miRNAs influida por el modelo, duración, intensidad y dosis de ejercicio. Queda pendiente, no obstante, conocer su origen, forma de transporte, destino, así como validar sus dianas génicas. Sin embargo, estos estudios muestran entre sí numerosas diferencias metodológicas (técnica de detección, número y tipo de c-miRNAs analizados, estrategia de normalización), en el diseño experimental (puntos de muestreo) y en las características de los sujetos (edad, historial de entrenamiento), que hace difícil, tanto establecer comparaciones directas entre ellos, como extraer conclusiones generales sólidas. Finalmente, este papel del ejercicio, como modulador del perfil de c-miRNAs, podría constituir una alternativa viable y coadyuvante a las terapias farmacológicas y dietéticas basadas en miRNAs que actualmente se encuentran en desarrollo. Además, su validación como biomarcadores de ejercicio podría contribuir al desarrollo de recomendaciones de ejercicio más precisas, a optimizar su aplicación como herramienta preventiva o terapéutica y a explorar los límites máximos del ejercicio saludable

Circulating microRNAs (c-miRNAs) are cell-to-cell communicators implicated in the regulation of molecular responses with strong potential in exercise and practical implications in health. Despite this fact, the number of papers published on this topic is scarce and with inconsistent results. Thus, the aim of this review was to summarize the information available, to analyze the heterogeneity of the results and to identify which are the future perspectives in this field of research. The results of the studies included in this revision clearly show that acute exercise and training induce a response in c-miRNA profile. This response depends on the model, intensity and dose of exercise. However, there are some questions which must be answered: what are the secretory organs or tissues, the mechanisms of transport, and the tissue and gene targets. A number of differences between studies in the methodologies used (detection technique, number of c-miRNAs analyzed, normalization strategy), in the experimental design (sampling points) and in the characteristics of the participants (aging, exercise background, dietary intake) makes it difficult to establish direct comparisons and to draw firm conclusions. Finally, this role of exercise as c-miRNA profile modulator, could be considered a valuable alternative to upcoming pharmacological and nutritional interventions based on miRNAs. Moreover, the validation of c-miRNAs as biomarkers of exercise will allow the development of more specific recommendations, using training as a therapeutic and preventive tool, and exploring the maximal limits for a safe and healthy exercise