Artículos de Investigación

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Differences in Physical Performance According to Contextual Variables in U21 Football Players
(2026)
Rodrigo Villaseca-Vicuña
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Pablo Merino-Muñoz
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Guillermo Cortes-Rocco
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Natalia Escobar
;
Marcelo Muñoz Lara
<jats:p>Understanding how contextual variables shape differences in match demands in youth football is essential for optimising performance and player development. Objective: This study aimed to compare physical and competitive performance according to playing position, match location, match result, and opponent quality in the physical and competitive performance of U21 football players from a professional Chilean club. Methods: Twenty male U21 players (19.2 ± 1.2 years) were monitored during 11 official matches using 10 Hz GPS devices (WIMU Pro™) and post-match Rating of Perceived Exertion (RPE). Variables included total distance (TD), high-speed running (HSR > 20 km/h), metres per minute (MM), accelerations/decelerations (N°AC/N°DC > 3 m·s−2), player load (PL), and peak velocity (PV). Contextual variables were classified by playing position, home/away, win/loss, and opponent quality (higher vs. lower rank). Results: Significant between-group differences were found across all contextual factors (p < 0.05). Midfielders (MFs) covered greater TD and reported higher RPE, while full-backs (FBs) and wingers (WGs) reached higher HSR and PV. Away and lost matches showed greater RPE, PL, and N°AC/N°DC, alongside more goals conceded. Facing higher-ranked opponents increased RPE and HSR but reduced explosive actions. Conclusions: Physical performance in U21 football is strongly modulated by contextual factors. Coaches should adjust training load and tactical strategies according to match conditions and positional roles to optimise adaptation and competitive readiness in developmental categories.</jats:p>
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Sleep health improvement trajectories after a pandemic: insights from a national health survey
(2026)
Jordi de Batlle
;
Esther Gracia-Lavedan
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Adriano D S Targa
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Mario Henríquez-Beltrán
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Ferran Barbé
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Study Objectives</jats:title> <jats:p>This study aimed to evaluate sleep health improvement trends in Catalonia, Spain, from 2020 to 2023 following the COVID-19 pandemic, and to identify disparities across demographic and socioeconomic groups.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>This repeated cross-sectional study analyzed 11 794 responses from eight waves of the Catalan Health Survey. Sleep health was assessed using the SATED and Ru-SATED questionnaires, covering six dimensions: Satisfaction, Alertness, Timing, Efficiency, Duration, and Regularity. Trends over time were evaluated, and stratified and interaction models assessed differences by sex, age, BMI, material deprivation, comorbidity burden, and living situation. Survey weights ensured population representativity.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Sleep health improved from mid-2021, then stabilized. Efficiency plateaued by late 2020, while Satisfaction remained the most unstable dimension. Sleep regularity diminished during the 2020 lockdowns but improved promptly afterward. Females consistently scored lower than males, though their improvement trajectories were similar (p-for-interaction = .906). Older adults (65+) and individuals with excess weight exhibited distinctive improvement trends (p-for-interaction = .023). Material deprivation was the strongest predictor of poor sleep health and delayed improvement (p-for-interaction = .024). Living alone had a temporary negative impact during lockdowns, which resolved by 2022. Finally, comorbidity burden affected baseline scores but not improvement trends (p-for-interaction = .467).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Sleep health improvement post-pandemic was uneven across sleep dimensions and population subgroups. Behavioral sleep dimensions improved earlier, while subjective satisfaction lagged. Socioeconomic factors, particularly material deprivation, were strongly associated with poorer and slower improvements. These findings highlight the importance of incorporating sleep health into pandemic preparedness and tailoring interventions to address both behavioral and structural determinants of health.</jats:p> </jats:sec>
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Effects of Knee Sleeve Density on Theoretical Neuromuscular Capacities Derived from the Force–Velocity–Power Profile in the Back Squat
(2026)
Jorge Leschot-Gatica
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Luis Romero-Vera
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Alberto Ñancupil-Andrade
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Claudio Hernández-Mosqueira
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Iván Molina-Márquez
<jats:p>Background: Neoprene knee sleeves are commonly used to enhance joint stability and mechanical performance during resistance training. However, the specific influence of sleeve density on the force–velocity–power (F–V–P) profile during multi-joint lower-body exercises such as the back squat remains unclear. This study aimed to compare the theoretical F–V–P parameters derived from back squat performance while wearing low-density (LD) versus high-density (HD) knee sleeves. Methods: Fifteen resistance-trained males completed an incremental back squat test under both LD and HD conditions. A linear position transducer recorded barbell displacement and velocity. Individual force–velocity relationships were modelled to determine maximal theoretical force (F0), velocity (V0), power (Pmax), and the F–V slope. Paired-sample t-tests, linear mixed models, and Cohen’s d effect sizes were calculated. Clinical relevance was assessed using a threshold defined as 0.2 × the standard deviation of the HD condition. Bayesian analyses were conducted to estimate the probability and magnitude of the observed effects. Results: No statistically significant differences were observed between sleeve conditions for F0, V0, Pmax, or F–V slope (p > 0.05, d ≤ 0.37). Nonetheless, HD sleeves yielded slightly higher mean values for F0, V0, and Pmax, exceeding the predefined threshold for practical relevance. Bayesian models showed moderate probabilities (~0.80) that HD sleeves outperformed LD, though with limited chances of crossing the clinical significance threshold. Conclusions: Although HD sleeves do not produce systematic changes in F–V–P parameters, their increased material stiffness may provide small yet practically meaningful mechanical advantages in high-force resistance training contexts.</jats:p>
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The Effectiveness of the Instruction of the Intonation of English Implications to L1 Spanish Trainee Teachers
(2019)
Marco Sandro Antonio Ugarte Olea
When it comes to Second and Foreign Language Teaching, the teaching of pronunciation has, for long, been neglected (Derwin & Munro, 2005) and it has not been given due attention in textbooks (Thompson, 1995). Additionally, studies tend to focus on only some intonation patterns such as wh- questions and yes-no questions, leaving other patterns which are as important unexplored. Thus, a research gap is generated. This study aims to narrow that gap by means of exploring the effectiveness of the teaching of intonation to Spanish-speaking trainee teachers at a Chilean university. The study focuses on a less familiar intonation pattern, that of utterances which express implied information, namely, implications. The study involved 9 participants (3 males, and 6 females) who were in the process of becoming English teachers and who were enrolled in an English phonetics course. All participants took a pre-test followed by a four-session intervention on the intonation of English implications and a post-test which involved the reading of 29 prompts. In order to compare pre- and post-test results, a Wilcoxon signed-ranked test was run. The results drawn from the non-parametric test revealed that the participants were able to perform English intonation for implications better after having received training (Mdn=22) than before the treatment (Mdn=11), Z=-2,668, p=0,008.
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Lingua Franca Core: A Plausible Option?
(2019)
Marco Sandro Antonio Ugarte Olea
<jats:p>One important decision that English language teachers should make is to decide on a pronunciation model. This decision should be based not only on mere preference, but also on technical information. This paper seeks to review the Lingua Franca Core (LFC), a pronunciation model proposed by Jennifer Jenkins (1998, 2000) in an attempt to facilitate communication for L2 speakers. This paper also presents a set of reactions that her proposal has prompted in scholars in the area of teaching English language pronunciation. Such reactions are the manifestation of rejection of the LFC which is based on a number of arguments. First, there is no agreement as to the number of interactions that occur in English in L1 and L2 contexts. Thus, the predominant use of L2 speakers of English is questioned. Secondly, the advantage of the intelligibility of non-native speakers over native speakers in interaction with other non-native speakers is also subjected to scrutiny. Finally, a special focus on implications for the L1-Spanish-speaking learner of English is proposed, as well as for English language teachers who teach pronunciation. For instance, a series of issues which could facilitate the learner’s workload is discussed. One the other hand, the implementation of the LFC implies that the amount of work to be done by the teacher would be drastically increased. This necessarily entails a disadvantage in terms of both time and teaching materials to be allocated by the English Language Teaching (ELT) professional.</jats:p>
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Study protocol and rationale of the “Cogni-action project” a cross-sectional and randomized controlled trial about physical activity, brain health, cognition, and educational achievement in schoolchildren
(2019)
Patricio Solis-Urra
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Jorge Olivares-Arancibia
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Ernesto Suarez-Cadenas
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Javier Sanchez-Martinez
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Fernando Rodríguez-Rodríguez
Background: Education and health are crucial topics for public policies as both largely determine the future wellbeing of the society. Currently, several studies recognize that physical activity (PA) benefits brain health in children. However, most of these studies have not been carried out in developing countries or lack the transference into the education field. The Cogni-Action Project is divided into two stages, a cross-sectional study and a crossover-randomized trial. The aim of the first part is to establish the associations of PA, sedentarism, and physical fitness with brain structure and function, cognitive performance and academic achievement in Chilean schoolchildren (10–14 years-old). The aim of the second part is to determinate the acute effects of three PA protocols on neuroelectric indices during a working memory and a reading task. Methods: PA and sedentarism will be self-reported and objectively-assessed with accelerometers in a representative subsample, whilst physical fitness will be evaluated through the ALPHA fitness test battery. Brain structure and function will be assessed by magnetic resonance imaging (MRI) in a randomized subsample. Cognitive performance will be assessed through the NeuroCognitive Performance Test, and academic achievement by school grades. In the second part 32 adolescents (12–13 year-old) will be cross-over randomized to these condition (i) “Moderate-Intensity Continuous Training” (MICT), (ii) “Cooperative High-Intensity Interval Training” (C-HIIT), and (iii) Sedentary condition. Neuroelectric indices will be measures by electroencephalogram (EEG) and eye-tracking, working memory by n-back task and reading comprehension by a reading task. Discussion: The main strength of this project is that, to our knowledge, this is the first study analysing the potential association of PA, sedentarism, and physical fitness on brain structure and function, cognitive performance, and academic achievement in a developing country, which presents an important sociocultural gap. For this purpose, this project will use advanced technologies in neuroimaging (MRI), electrophysiology (EEG), and eye-tracking, as well as objective and quality measurements of several physical and cognitive health outcomes. Trial registration: ClinicalTrials.gov identifier: NCT03894241 Date of register: March 28, 2019. Retrospectively Registered
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Numerical processing profiles in children with varying degrees of arithmetical achievement
(2019)
Nancy Estévez-Pérez
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Danilka Castro-Cañizares
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Eduardo Martínez-Montes
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Vivian Reigosa-Crespo
Recent studies show basic cognitive abilities such as the rapid and precise apprehension of small numerosities in object sets (“subitizing”), verbal counting and numerical magnitude comparison significantly influence the acquisition of arithmetic and continues to modulate more advanced stages of mathematical cognition. Additionally, children with low arithmetic achievement (LAA) and Developmental Dyscalculia (DD) exhibit significant deficits in these cognitive processes. Nevertheless, the different cognitive profiles of children with varying degrees of numerical and arithmetic processing deficits have not been sufficiently characterized, despite its potential relevance to the stimulation of numerical cognition and the design of appropriate intervention strategies. Here, the cognitive profiles of groups of typically developing children, children with low arithmetical achievement and DD, exhibiting typical and atypical subitizing ability were contrasted. The results suggest that relatively independent neurocognitive mechanisms may produce distinct profiles at the behavioral level and suggest children with low arithmetic performance exhibiting atypical subitizing abilities are not only significantly slower, but rely on compensatory mechanisms and strategies compared to typical subitizers. The role of subitizing as a correlate of arithmetic fluency is revised in the light of the present findings.
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High Prevalence of Food Insecurity and Factors Associated with Haitian Immigrants in Southern Chile
(2019)
Eduard Maury-Sintjago
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Alejandra Rodríguez-fernández
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Danny E. García
;
Julio Parra-Flores
The objective was to determine the association between sociodemographic factors and food insecurity (FI) in Haitian immigrants in southern Chile. An analytical cross-sectional design was used. The sample consisted of Haitian immigrants residing in Southern Chile, who were recruited from community centers and completed a sociodemographic questionnaire and the Latin-American and Caribbean Food Security Scale. Multivariable analyses were performed to identify factors associated with FI. FI prevalence in the 234 participants was 78%; 60% had severe FI. Having children (OR 3.6; 95% CI 1.6–7.4), limited Spanish proficiency (OR 3.5; 95% CI 1.8–7.3), no access to basic services (OR 2.8; 95% CI 1.2–6.4), and not being a legal permanent resident (OR 2.4; 95% CI 1.1–6.1) were associated with significantly higher odds of FI. Over three-quarters of Haitian immigrants in southern Chile suffer from FI. Tailored intervention strategies are needed to address this major public-health issue, with a special focus on those at highest risk, including families with children, and those with limited Spanish proficiency, no access to basic services, and without legal permanent resident status.

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