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.

Apparent Ventricular Dysfunction in Elite Young Athletes: Another Form of Cardiac Adaptation of the Athlete's Heart.

BACKGROUND: The authors previously observed that some high-performance athletes, irrespective of type of sport, can show echocardiographically determined low left ventricular ejection fractions (LVEF; <52%) together with normal heart rates and nondilated left ventricular (LV) cavities under resting conditions. The aim of this study was to determine if this phenomenon is associated with dyssynchronous motion of the interventricular septum relative to the lateral LV wall. METHODS: Results of M-mode and two-dimensional echocardiography and pulsed-wave, pulsed-wave tissue, and color tissue Doppler were compared in 70 athletes (mean age, 20 ± 7 years; 77% men) with low LVEFs (<52%) participating in a wide variety of sports and a control group of 564 athletes (mean age, 22 ± 7 years; 61% men) with normal LVEFs (≥52%). RESULTS: No between-group differences were found in cardiac dimensions or QRS duration (indicating no electrical dyssynchrony in the low-LVEF group compared with the normal-LVEF group), but analysis of mechanical interventricular and intraventricular dyssynchrony showed that time intervals between QRS onset and the different systolic waves were all lengthened in the low-LVEF group (P < .05 for all). Values of interventricular mechanical delay were higher in the low-LVEF group (P = .012), though they did not reach pathologic limits. Peak aerobic performance was independent of LVEF. The results did not change materially when analyzing data separately by sex or sport. CONCLUSIONS: Some young highly trained athletes might show depressed LVEF (<52%) with a nondilated LV cavities in the early phase of cardiac adaptations, which seems to be linked to longer LV contraction times, with the right ventricle unaffected. These echocardiographic findings, although not highly prevalent, could be considered another characteristic of the cardiac adaptations to the demands of elite sports with no detriment in performance.

Bicuspid aortic valve behaviour in elite athletes.

AIMS: To determine the prevalence and characteristics of bicuspid aortic valve (BAV) among elite athletes and to analyse the effect of long-term exercise training on their aortas. METHODS AND RESULTS: Consecutive BAV and tricuspid aortic valve (TAV) elite athletes from a population of 5136 athletes evaluated at the Sports Medicine Center of the Spanish National Sports Council were identified using echocardiography. A total of 41 BAV elite athletes were matched with 41 TAV elite athletes, and 41 BAV non-athletic patients from three Spanish tertiary hospitals. Sixteen BAV elite athletes who had undergone at least two cardiac evaluations separated by more than 3 years were selected to assess their clinical course. The prevalence of BAV in elite athletes was 0.8%. The proximal ascending aorta was larger for both BAV groups in comparison to TAV athletes (P = 0.001). No differences in aortic diameters were found between BAV athletes and BAV non-athletes. In BAV elite athletes, the annual growth rates for aortic annulus, sinuses of Valsalva, sinotubular junction, and proximal ascending aorta were 0.04 ± 0.24, 0.11 ± 0.59, 0.14 ± 0.38, and 0.21 ± 0.44 mm/year, respectively. Aortic regurgitation was the only functional abnormality, but no significant progression was found. CONCLUSION: High-intensity training and sports competition may not aggravate BAV condition during elite athletes' careers. BAV elite athletes with mild-to-moderately dilated aortas may engage in high dynamic cardiovascular exercise without adverse consequences, although an echocardiographic follow-up is recommended.

Reference Values of Aortic Root in Male and Female White Elite Athletes According to Sport.

BACKGROUND: There is limited information regarding the aortic root upper physiological limits in all planes in elite athletes according to static and dynamic cardiovascular demands and sex. METHODS AND RESULTS: A cross-sectional study was performed in 3281 healthy elite athletes (2039 men and 1242 women) aged 23.1±5.7 years, with body surface area of 1.9±0.2 m2 and 8.9±4.9 years and 19.2±9.6 hours/week of training. Maximum end-diastolic aortic root diameters were measured in the parasternal long axis by 2-dimensional echocardiography. Age, left ventricular mass, and body surface area were the main predictors of aortic dimensions. Raw values were greater in males than in females (P<0.0001) at all aortic root levels. Dimensions corrected by body surface area were higher in men than in women at the aortic annulus (13.1±1.7 versus 12.9±1.7 mm/m2; P=0.007), without significant differences at the sinus of Valsalva (16.3±1.9 versus 16.3±1.9 mm/m2; P=0.797), and were smaller in men at the sinotubular junction (13.6±1.8 versus 13.8±1.8 mm/m2; P=0.008) and the proximal ascending aorta (13.8±1.9 versus 14.1±1.9 mm/m2; P=0.001). Only 1.8% of men and 1.5% of women had values >40 mm and 34 mm, respectively. Raw and corrected aortic measures at all levels were significantly greater in sports, with a high dynamic component in both sexes, except for corrected values of the sinotubular junction in women. CONCLUSIONS: Aortic root dimensions in healthy elite athletes are within the established limits for the general population. This study describes the normal dimensions for healthy elite athletes classified according to sex and dynamic and static components of their sports.

Circulating inflammatory miRNA signature in response to different doses of aerobic exercise.

While moderate acute exercise has been associated with strong anti-inflammatory mechanisms, strenuous exercise has been linked to deleterious inflammatory perturbations. It is therefore fundamental to elucidate the mechanisms that regulate the exercise-induced inflammatory cascade. Information on novel regulators such as circulating inflammatory microRNAs (c-inflammamiRs) is incomplete. In this study, we evaluated the response of a panel of c-inflammamiRs to different doses of acute aerobic exercise. We first studied the exercise-induced inflammatory cascade in serum samples of nine active middle-aged males immediately before and after (0 h, 24 h, 72 h) 10-km, half-marathon, and marathon races. Next, we analyzed the circulating profile of 106 specific c-inflammamiRs immediately before) and after (0 h, 24 h) 10-km (low inflammatory response) and marathon (high inflammatory response) races. Analysis of classical inflammatory parameters revealed a dose-dependent effect of aerobic exercise on systemic inflammation, with higher levels detected after marathon. We observed an increase in miR-150-5p immediately after the 10-km race. Levels of 12 c-inflammamiRs were increased immediately after the marathon (let-7d-3p, let-7f-2-3p, miR-125b-5p, miR-132-3p, miR-143-3p, miR-148a-3p, miR-223-3p, miR-223-5p, miR-29a-3p, miR-34a-5p, miR-424-3p, and miR-424-5p). c-inflammamiRs returned to basal levels after 24 h. Correlation and in silico analyses supported a close association between the observed c-inflammamiR pattern and regulation of the inflammatory process. In conclusion, we found that different doses of acute aerobic exercise induced a distinct and specific c-inflammamiR response, which may be associated with control of the exercise-induced inflammatory cascade. Our findings point to c-inflammamiRs as potential biomarkers of exercise-induced inflammation, and hence, exercise dose.

Physiological determinants of speciality of elite middle- and long-distance runners.

The aim of this study was to determine which physiological variables predict excellence in middle- and long-distance runners. Forty middle-distance runners (age 23 ± 4 years, body mass 67.2 ± 5.9 kg, stature 1.80 ± 0.05 m, VO(2max) 65.9 ± 4.5 ml · kg(-1) · min(-1)) and 32 long-distance runners (age 25 ± 4 years, body mass 59.8 ± 5.1 kg, stature 1.73 ± 0.06 m, VO(2max) 71.6 ± 5.0 ml · kg(-1) · min(-1)) competing at international standard performed an incremental running test to exhaustion. Expired gas analysis was performed breath-by-breath and maximum oxygen uptake (VO(2max)) and two ventilatory thresholds (VT(1) and VT(2)) were calculated. Long-distance runners presented a higher VO(2max) than middle-distance runners when expressed relative to body mass (P < 0.001, d = 1.18, 95% CI [0.68, 1.68]). At the intensities corresponding to VT(1) and VT(2), long-distance runners showed higher values for VO(2) expressed relative to body mass or %VO(2max), speed and oxygen cost of running (P < 0.05). When oxygen uptake was adjusted for body mass, differences between groups were consistent. Logistic binary regression analysis showed that VO(2max) (expressed as l · min(-1) and ml · kg(-1) · min(-1)), VO(2VT2) (expressed as ml · kg(-0.94) · min(-1)), and speed at VT(2) (v(VT2)) categorized long-distance runners. In addition, the multivariate model correctly classified 84.7% of the athletes. Thus, VO(2max), VO(2VT2), and v(VT2) discriminate between elite middle-distance and long-distance runners.

Cardiovascular adaptation, functional capacity and Angiotensin-converting enzyme I/D polymorphism in elite athletes.

INTRODUCTION AND OBJECTIVES: Angiotensin-converting enzyme (ACE) is associated with the development of cardiac hypertrophy and improved physical fitness. The objective of this study was to investigate the relationship between the ACE gene insertion/deletion (I/D) polymorphism and adaptation to sports training. METHODS: The study included 299 elite Spanish athletes (193 men and 106 women) from 32 different sports disciplines, which were grouped according to their static and dynamic components. All participants underwent body composition analysis, Doppler echocardiography at rest, and ergospirometry. Their ACE genotype was determined using the polymerase chain reaction. RESULTS: The most common genotype in both males and females was the deletion-insertion (DI) heterozygote (57.5% and 54.7%, respectively), followed by the DD homozygote (30.6% and 34.9%), and the II homozygote (11.9% and 10.4%). Differences in morphometric and functional cardiac adaptation were observed between the different sports disciplines, but there was no statistically significant relationship with the ACE I/D polymorphism. Moreover, when athletes with different genotypes were compared, the only differences observed were between the DD and DI groups in female athletes, who differed in body mass index and longitudinal right atrial dimension. CONCLUSIONS: The ACE I/D polymorphism did not appear to influence cardiovascular adaptation in response to training. However, the DI genotype was the most common, probably because the sample was biased by being made up of elite athletes.

PPARGC1A genotype (Gly482Ser) predicts exceptional endurance capacity in European men.

Animal and human data indicate a role for the peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PPARGC1A) gene product in the development of maximal oxygen uptake (V(O2 max)), a determinant of endurance capacity, diabetes, and early death. We tested the hypothesis that the frequency of the minor Ser482 allele at the PPARGC1A locus is lower in World-class Spanish male endurance athletes (cases) [n = 104; mean (SD) age: 26.8 (3.8) yr] than in unfit United Kingdom (UK) Caucasian male controls [n = 100; mean (SD) age: 49.3 (8.1) yr]. In cases and controls, the Gly482Ser genotype met Hardy-Weinberg expectations (P > 0.05 in both groups tested separately). Cases had significantly higher V(O2 max) [73.4 (5.7) vs. 29.4 ml x kg(-1) x min(-1) (3.8); P < 0.0001] and were leaner [body mass index: 20.6 (1.5) vs. 27.6 kg/m2 (3.9); P < 0.0001] than controls. In unadjusted chi2 analyses, the frequency of the minor Ser482 allele was significantly lower in cases than in controls (29.1 vs. 40.0%; P = 0.01). To assess the possibility that genetic stratification could confound these observations, we also compared Gly482Ser genotype frequencies in Spanish (n = 164) and UK Caucasian men (n = 381) who were unselected for their level of fitness. In these analyses, Ser482 allele frequencies were very similar (36.9% in Spanish vs. 37.5% in UK Caucasians, P = 0.83), suggesting that confounding by genetic stratification is unlikely to explain the association between Gly482Ser genotype and endurance capacity. In summary, our data indicate a role for the Gly482Ser genotype in determining aerobic fitness. This finding has relevance from the perspective of physical performance, but it may also be informative for the targeted prevention of diseases associated with low fitness such as Type 2 diabetes.

Frequency of the C34T mutation of the AMPD1 gene in world-class endurance athletes: does this mutation impair performance?

The C34T mutation in the gene encoding for the skeletal muscle-specific isoform of AMP deaminase (AMPD1) is a common mutation among Caucasians (i.e., one of five individuals) that can impair exercise capacity. The purpose of this study was twofold. First, we determined the frequency distribution of the C34T mutation in a group of top-level Caucasian (Spanish) male endurance athletes (cyclists and runners, n = 104). This group was compared with randomly selected Caucasian (Spanish) healthy (asymptomatic) nonathletes (n = 100). The second aim of this study was to compare common laboratory indexes of endurance performance (maximal oxygen uptake or ventilatory thresholds) within the group of athletes depending on their C34T AMPD1 genotype. The frequency of the mutant T allele was lower (P < 0.05) in the group of athletes (4.3%) compared with controls (8.5%). On the other hand, indexes of endurance performance did not differ (P > 0.05) between athlete carriers or noncarriers of the C34T mutation (e.g., maximal oxygen uptake 72.3 +/- 4.6 vs. 73.5 +/- 5.9 ml.kg(-1).min(-1), respectively). In conclusion, although the frequency distribution of the mutant T allele of the AMPD1 genotype is lower in Caucasian elite endurance athletes than in controls, the C34T mutation does not significantly impair endurance performance once the elite-level status has been reached in sports.