The influence of the perceived requirements of the next match and motivation on the mental fatigue of soccer players

The high cognitive and/or emotional demands of competition can lead to a state of mental fatigue which has shown to be detrimental to soccer performance. However, there is a need to further understand the true mental demands of soccer players. The aim of the present study was to analyze the influence of motivation and the perceived requirements of the next match on mental fatigue perceived by soccer players over the passing of a season. The combined effect of both variables on the perception of mental fatigue, as well as the influence of the time of the season on perceived mental fatigue, were also analyzed. Twenty-six semi-professional Spanish male players (M = 26.31 ± 5.18 years) participated in the present study, conducted during the 2020-2021 season. Perceived mental fatigue and motivation were measured at each training session. The perceived requirements of the next match were also measured in each of the competitive weeks. Linear mixed models were run with R Studio to examine the influence of motivation and the perceived difficulty of the next match on perceived mental fatigue, the combined effect of both variables on perceived mental fatigue, and the influence of the passing of the season on perceived mental fatigue. The results showed a negative and significant influence of motivation on perceived mental fatigue (p < 0.001) and a positive and significant influence of the perceived requirements of the next match on perceived mental fatigue (p < 0.001). Regarding the combined effect, there was a positive and significant effect (p < 0.01) of the perceived difficulty of the next match on the relation between motivation and perceived mental fatigue. A negative influence of season passage on perceived mental fatigue levels was found (p < 0.001). We recommended coaches to consider using the most motivating training tasks when higher next-match requirements are perceived and to be careful with avoidance strategies for mental fatigue, especially at the beginning of the season.

Identity and functional characterisation of the transporter supporting the Na+ -dependent high-affinity NO3 - uptake in Zostera marina L

Zostera marina is a seagrass, a group of angiosperms that evolved from land to live submerged in seawater, an environment of high salinity, alkaline pH and usually very low NO₃ ^- . In 2000, we reported the first physiological evidence for the Na⁺ -dependent high-affinity NO₃ ^- uptake in this plant. Now, to determine the molecular identity of this process, we searched for NO₃ ^- transporters common to other vascular plants encoded in Z. marina's genome. We cloned two candidates, ZosmaNPF6.3 and ZosmaNRT2 with its partner protein ZosmaNAR2. ZosmaNAR2 expression levels increase up to 4.5-fold in Z. marina leaves under NO₃ ^- -deficiency, while ZosmaNRT2 and ZosmaNPF6.3 expressions were low and unaffected by NO₃ ^- . NO₃ ^- transport capacity, kinetic properties and H⁺ or Na⁺ -dependence were examined by heterologous expression in the Hansenula polymorpha high-affinity NO₃ ^- transporter gene disrupted strain (∆ynt1). ZosmaNPF6.3 functions as a H⁺ -dependent NO₃ ^- transporter, without functionality at alkaline pH and apparent dual kinetics (K_M  = 11.1 µM at NO₃ ^- concentrations below 50 µM). ZosmaNRT2 transports NO₃ ^- in a H⁺ -independent but Na⁺ -dependent manner (K_M  = 1 mM Na⁺ ), with low NO₃ ^- affinity (K_M  = 30 µM). When ZosmaNRT2 and ZosmaNAR2 are co-expressed, a Na⁺ -dependent high-affinity NO₃ ^- transport occurs (K_M  = 5.7 µM NO₃ ^- ), mimicking the in vivo value. These results are discussed in the physiological context, providing evidence that ZosmaNRT2 is a Na⁺ -dependent high-affinity NO₃ ^- transporter, the first of its kind to be functionally characterised in a vascular plant, that requires ZosmaNAR2 to achieve the necessary high-affinity for nitrate uptake from seawater.

Molecular Characterization of ZosmaNRT2, the Putative Sodium Dependent High-Affinity Nitrate Transporter of Zostera marina L

One of the most important adaptations of seagrasses during sea colonization was the capacity to grow at the low micromolar nitrate concentrations present in the sea. In contrast to terrestrial plants that use H⁺ symporters for high-affinity NO₃⁻ uptake, seagrasses such as Zostera marina L. use a Na⁺-dependent high-affinity nitrate transporter. Interestingly, in the Z. marina genome, only one gene (Zosma70g00300.1; NRT2.1) is annotated to this function. Analysis of this sequence predicts the presence of 12 transmembrane domains, including the MFS domains of the NNP transporter family and the “nitrate signature” that appears in all members of the NNP family. Phylogenetic analysis shows that this sequence is more related to NRT2.5 than to NRT2.1, sharing a common ancestor with both monocot and dicot plants. Heterologous expression of ZosmaNRT2-GFP together with the high-affinity nitrate transporter accessory protein ZosmaNAR2 (Zosma63g00220.1) in Nicotiana benthamiana leaves displayed four-fold higher fluorescence intensity than single expression of ZosmaNRT2-GFP suggesting the stabilization of NRT2 by NAR2. ZosmaNRT2-GFP signal was present on the Hechtian-strands in the plasmolyzed cells, pointing that ZosmaNRT2 is localized on the plasma membrane and that would be stabilized by ZosmaNAR2. Taken together, these results suggest that Zosma70g00300.1 would encode a high-affinity nitrate transporter located at the plasma membrane, equivalent to NRT2.5 transporters. These molecular data, together with our previous electrophysiological results support that ZosmaNRT2 would have evolved to use Na⁺ as a driving ion, which might be an essential adaptation of seagrasses to colonize marine environments.

[Comparison of self-reported anthropometric variables and real measurement data]

The objectives of this study were to evaluate self-reporting of weight, height, and waist circumference, and to compare that perception with the real measurements in college students of the MESPYN cohort--Medellin, Salud Pública y Nutrición--from the University of Antioquia (UdeA), Colombia. A cross-sectional study was conducted starting with the first measurement of the MESPYN Cohort 2009-2010. The sample included volunteer students from different academic areas. Self-perception of weight, height, and waist circumference were recorded before the real measurements were performed. Intraclass correlation coefficients (ICC) were calculated for all the variables, and an alpha of 0.05 was used. The concordance between real measurements and self-referred values was evaluated with the Bland and Altman method. 424 volunteer students were included. The average real weight (kg) in males was 67.4 +/- 10.4 and self-reported: 67.0 +/- 11.0; in females the real value was 55.7 +/- 10.1 and self-reported: 55.0 +/- 9.0. The average real height (m) in males was 1.73 +/- 6.1 and self-reported: 1.73 +/- 6.0; in females the real value was 1.60 +/- 5.9 and self-reported: 1.61 +/- 6.0. In males, the average real waist circumference (cm) was 76.6 +/- 8.0 and self-reported: 75.0 +/- 14.0; in females the real value was 69.9 +/- 8.0 and self-reported: 70.0 +/- 9.0. Weight ICC: 0.956, 95% CI (0.95; 0.97), (p < 0.01); height ICC: 0.953, 95%IC (0.91; 0.97), (p < 0.01), and waist circumference ICC: 0.593, 95% IC (0.55; 0.65), (p < 0.01). In conclusion, anthropometric nutritional evaluation of UdeA students can be performed with self-reported data for weight and height, but the evaluation of abdominal obesity requires direct measurement of waist circumference.