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.

Expression of TLR3, 4, 7 and 9 in cutaneous malignant melanoma: relationship with clinicopathological characteristics and prognosis

Toll-like receptors (TLRs) have achieved an extraordinary amount of interest in cancer research due to their role in tumor progression. The aim of this study was to investigate the expression and clinical relevance of TLR3, 4, 7 and 9 in cutaneous malignant melanoma (CMM). The expression levels of TLR3, 4, 7 and 9 were analyzed in tumors from 30 patients with CMM. The analysis was performed by immunohistochemistry, and the results were correlated with various clinicopathological findings and with relapse-free survival. Our results indicate that there was a wide variability in the immunostaining score values for each receptor. Positive staining for TLRs was generally found in tumor cells, especially for TLR4 and TLR9. Nevertheless, a significant percentage of tumors also showed TLR4 expression in mononuclear inflammatory cells (62.1 %) and in fibroblast-like cells (34.5 %). Our results showed no significant association between score values for each TLR and clinicopathological characteristics of patients. However, our results demonstrated that high TLR4 expression was significantly associated with a shortened relapse-free survival (p = 0.001). Therefore, TLR4 expression may be a new prognostic factor of unfavorable evolution in cutaneous malignant melanoma.

Match activity and physiological responses during a junior female singles tennis tournament

OBJECTIVE

To assess physiological load in conjunction with individual patterns of match-play activity in junior female tennis players during actual singles tennis competition.

METHODS

Eight elite junior female tennis players (n = 8; mean (SD) age, 17.3 (1.9) years) took part in a 2 day invitational tournament. Activity pattern analysis was performed during competitive matches. Heart rate and blood lactate concentrations were measured during selected changeovers breaks in play.

RESULTS

The activity profile of junior female players were: rally duration, (mean (SD)) 8.2 (5.2) s; rest time between rallies, 17.7 (6.5) s; effective playing time, 21.9 (3.8)%; strokes per rally, 2.7 (1.7); changes of direction per rally, 2.3 (1.4). The mean (SD) heart rate and blood lactate concentration recorded during the matches were 161 (5) beats/min and 2.0 (0.8) mmol/litre. Heart rate and blood lactate concentration values were influenced by the characteristics of the match and mean (SD) heart rate was significantly higher (p = 0.004) during service games (166 (15.4) beats/min) than in return games (156 (19.6) beats/min), while blood lactate concentrations were not significantly different (p = 0.83) between service (2.3 (0.6) mmol/litre) and return games (2.3 (0.9) mmol/litre). We found a significant (p<0.05) positive relationship between rally duration, strokes per rally, changes of direction and blood lactate and heart rate responses, with stronger correlations when the players were serving.

CONCLUSIONS

The physiological (ie, blood lactate and heart rate) responses associated with match play were influenced by the characteristics of the match (rally duration, strokes per rally and changes of direction), with higher heart rate on service position. Training programs should reflect these demands placed on female players during competitive match play.

Activity patterns, blood lactate concentrations and ratings of perceived exertion during a professional singles tennis tournament

OBJECTIVE

To examine the game characteristics and physiological (ie, blood lactate concentration) and perceptual (ie, rating of perceived exertion, RPE) responses during actual tennis competition in professional performers.

METHODS

Eight trained and internationally ranked (Association of Tennis Professionals rankings) male tennis players were studied during singles matches (best of three sets) played on an outdoor clay court surface during a professional, invitational tournament. Blood lactate concentrations (n = 53) and RPE (n = 113) were determined at selected change-overs during the game. The variables describing the characteristics of the matches, (a) duration of rallies (DRs); (b) rest time (RT); (c) effective playing time (EPT); and (d) shots per rally (SR), were determined from video recordings.

RESULTS

The mean (SD) values for the match-play activity variables were DR 7.5 (7.3) s, RT 16.2 (5.2) s, EPT 21.5 (4.9%), SR 2.7 (2.2) shots. Average blood lactate concentration and RPE values were 3.8 (2.0) mmol/l and 13 (2). Blood lactate concentrations and RPE values were significantly higher (p<0.01) in service games than in receiving games. Both blood lactate concentration and RPE values were significantly correlated with SR and DR (r = 0.80 to 0.28; p<0.001).

CONCLUSIONS

Blood lactate concentrations and RPE were found to be influenced by the characteristics of the match and the playing situation (ie, serving or returning). These specific situations might be used to alter the overload training stimulus during tennis on-court practice.

p73 cooperates with Ras in the activation of MAP kinase signaling cascade

The p73 gene is capable of inducing cell cycle arrest, apoptosis, senescence, differentiation and to cooperate with oncogenic Ras in cellular transformation. Ras can be considered as a branch point in signal transduction, where diverse extracellular stimuli converge. The intensity of the mitogen-activated protein kinase (MAPK) cascade activation influences the cellular response to Ras. Despite the fundamental role of p53 in Ras-induced growth arrest and senescence, it remains unclear how the Ras/MEK/ERK pathway induces growth arrest in the absence of p53. We report here that oncogenic Ras stabilizes p73 resulting in p73 accumulation and enhancement of its activity. p73, in turn, induces a sustained activation of the MAP kinase cascade synergizing with oncogenic Ras. We also found that inhibition of p73 function modifies the cellular outcome to Ras activation inhibiting Ras-dependent differentiation. Here, we show for the first time that there is a signaling loop between Ras-dependent MAPK cascade activation and p73 function.

Importance of wash riding in kayaking training and competition

PURPOSE

The use of different wash-riding techniques is common during kayak training and competition. Changes in wash-riding positions could imply a different exercise intensity. The aim of this study, therefore, was to quantify the energy savings made when a kayaker is "wash riding."

METHODS

Eight male international flat water kayakers, who performed a field test of 2000 m in each of the four wash-riding positions, head (H), right wave (RW), left wave (LW), and end position (V), were studied. The data investigated were: time, stroke rate, blood lactate (BL), heart rate (HR), and rate of perceived exertion (RPE). Under laboratory conditions kayakers performed the same intensity of exercise in a kayak ergometer, and HR, oxygen uptake (VO2), BL, mean power output (W), and RPE were measured.

RESULTS

The results show significant differences (P < 0.05) among H, RW/LW, and V. The mean values for BL (P < 0.05) were 4.2, 2.0, 2.2, and 1.5 mmol.L-1, for H, RW, LW, and V, respectively. RPE also revealed differences, with values of 15, 12.6, 12.6, and 9.7 for H, RW, LW, and V, respectively. Mean power output gave values of 190.3 (H), 155.6 (RW and LW), and 129.5 (V) W. HR was different between H and V (172 and 151), while stroke rate was different among the parameters H, RW, and V (93.7, 88.8, and 87.6, respectively). The VO2 in the kayak ergometer test showed a difference between H and V (3.78 and 2.23 L.min-1).

CONCLUSIONS

We conclude that "wash riding" involves a saving in energy cost of between 18% and 31.9%, depending on the position. This conclusion is of importance for the quantification and calibration of kayak training and competition.