Sam Hernández-Jaña

Prof. Sam Hernández-Jaña

IRyS Research Group, School of Physical Education, Pontificia Universidad Católica de Valparaíso
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Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
DEDanica Escobar-Gómez
Danica Escobar-Gómez
Carlos Cristi-MonteroCarlos Cristi-Montero
Carlos Cristi-Montero
José Castro-PiñeroJosé Castro-Piñero
José Castro-Piñero
Fernando Rodriguez-RodríguezFernando Rodriguez-Rodríguez
Fernando Rodriguez-Rodríguez
Strategies to reduce the spread of coronavirus disease 2019 (COVID-19) have caused different behavioural modifications in all populations. Therefore, this study aimed to determine changes in active commuting, moderate-to-vigorous physical activity (MVPA), physical fitness, and sedentary time during the COVID-19 pandemic in Chilean parents. Eighty-six fathers (41.30 ± 6.82 years) and 294 mothers (40.68 ± 6.92 years) of children from different schools from Valparaíso, Chile, participated. Inclusion criteria were adults with schoolchildren who were resident in Chile during the research period. Convenience sampling was used as a non-probabilistic sampling technique. Respondents completed a self-reported online survey about active commuting, MVPA, self-perceived physical fitness, and sedentary time July–September 2020 during the first pandemic period. Comparisons between before and during the pandemic were performed using t-tests and covariance analysis (ANCOVA), establishing a significance level at p < 0.05. Most participants stayed at home during the pandemic, whereas active and passive commuting significantly decreased in both fathers and mothers (p < 0.001). MVPA and physical fitness scores reduced considerably (p < 0.05), while sedentary time significantly increased (p < 0.05), independent of the sex of parents and children’s school type. Differences by age groups and the number of children were more heterogeneous, as younger parents showed a larger decrease in MVPA (p < 0.05) and physical fitness score (p < 0.05). Additionally, parents with one child showed a larger decrease in sedentary time (p < 0.05) than those with two or more children. The COVID-19 pandemic significantly affected healthy behaviours. Hence, health policies should promote more strategies to mitigate the long-term health effects of the pandemic on Chilean parents.

5 February 2025 in Social Science & Medicine
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Journal Article
Closed access
Humberto Peña-JorqueraHumberto Peña-Jorquera
Humberto Peña-Jorquera
Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
JSJavier Sanchez-Martinez
Javier Sanchez-Martinez
Juan Pablo Espinoza PuellesJuan Pablo Espinoza Puelles
Juan Pablo Espinoza Puelles
RMRicardo Martínez-Flores
Ricardo Martínez-Flores
Carlos Cristi-MonteroCarlos Cristi-Montero
Carlos Cristi-Montero

Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
THTamara Huber-Pérez
Tamara Huber-Pérez
XPXimena Palma-Leal
Ximena Palma-Leal
PGPaola Guerrero-Ibacache
Paola Guerrero-Ibacache
Valentina CamposValentina Campos
Valentina Campos
Carlos Cristi-MonteroCarlos Cristi-Montero
Carlos Cristi-Montero
Background: the present study aimed to investigate the effects of a single nutritional preventive session previous to a critical period linked to fat gain in university students with overweightness and obesity, emulating a nutritional session of a public health system. Methods: In this single-blind randomized controlled trial, 23 students met all the criteria to be included (20.91 ± 2.52-year-old; 52.2% women) who were divided into two groups: intervention group (IG) and control group (CG). Fat mass (FM) by dual-energy X-ray absorptiometry (DXA), physical activity by accelerometry, feeding evaluation through three questionnaires, and a set of healthy lifestyle recommendations were evaluated before and after the national holidays (NH). Results: Our findings showed that FM increased significantly in the CG, but not in the IG (CG = 428.1 g; IG = 321.9 g; Δ = 106.2 g; p = 0.654 [95% CI = −379.57, 591.92]). However, no differences were found during the NH between them (Hedges’ g effect size = 0.19; p = 0.654). In addition, no statistical differences were observed between groups in feeding evaluations, the set of recommendations performed, and physical activity. Conclusion: a single preventive session before a critical period, using a similar counselling approach as used in the public health system, might not be enough to promote changes in eating and physical activity patterns and preventing fat gain in overweight/obese university students. Long-term interventions are a must.

1 February 2021 in International Journal of Morphology
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Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
CJCarlos Jorquera-Aguilera
Carlos Jorquera-Aguilera
AAAtilio Aldo Almagià-Flores
Atilio Aldo Almagià-Flores
RYRodrigo Yáñez-Sepúlveda
Rodrigo Yáñez-Sepúlveda
FRFernando Rodríguez-Rodríguez
Fernando Rodríguez-Rodríguez
El fútbol es el deporte más popular del mundo, por lo que las variables que benefician el rendimiento y el éxito deportivo generan un gran interés y ocupan un rol esencial en la preparación de futbolistas. Por lo tanto, el objetivo del presente estudio fue analizar la composición corporal y la proporcionalidad según la categoría y posición de juego. Se evaluaron a través de antropometría a 111 futbolistas de la selección chilena de fútbol en las categorías sub-15 (14,6±0,3 años), sub-17 (16,3±0,5 años), sub-20 (19,0±0,7 años) y elite (24,3±4,7 años); la significación se estableció en p<.05. En cuanto al peso, los porteros tuvieron el valor más alto para su posición; la categoría sub-20 obtuvo el valor más alto (83,7±3,8 kg). En cuanto a la estatura, los defensas centrales elite y la categoría sub-17 tuvieron los valores más altos (187,0±4,2 cm y 179,9±3,5 cm, respectivamente). Los porteros de todas las categorías tienen los mayores valores de IMC, siendo la categoría elite el más alto (25,1±1,3 kg/m2). Los delanteros/extremos sub-17 años tienen los valores más altos de masa muscular (60,5±8,0 %), mientras que los laterales sub-15 tienen los valores más bajos de masa grasa (9,6±0,7 %). Los jugadores de la selección chilena de fútbol tienen valores similares a los de otras investigaciones con jugadores de la misma edad y categoría; sin embargo, las categorías más jóvenes presentan diferencias significativas en las variables que proporcionan ventajas durante un partido con la categoría elite. Por lo tanto, se debe hacer énfasis en equiparar las condiciones físicas antes de promover a un jugador a categorías de mayor edad.

23 March 2022 in Retos
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RYRodrigo Yáñez-Sepúlveda
Rodrigo Yáñez-Sepúlveda
Josivaldo De Souza-LimaJosivaldo De Souza-Lima
Josivaldo De Souza-Lima
JCJuan Pablo Zavala Crichton
Juan Pablo Zavala Crichton
APArturo Prat-Lopicich
Arturo Prat-Lopicich
Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
JAJorge Eduardo Olivares Arancibia
Jorge Eduardo Olivares Arancibia
En la actualidad conocer los parámetros antropométricos de la composición corporal (CC) y el nivel de condición física en niños y niñas adquiere cada vez una mayor importancia. El objetivo del presente estudio fue determinar la relación entre características antropométricas, composición corporal y capacidades físicas en escolares de la comuna de Quintero. En la investigación participaron 135 estudiantes (11,07 ± 2,3 años). Se midieron las variables antropométricas utilizando el protocolo de ISAK. El IMC peso/estatura2, porcentaje de grasa con la fórmula Slaughter, y el índice de conicidad con la fórmula de Valdez. Para medir las capacidades físicas se utilizó una adaptación de la batería EUROFIT®. Las variables fueron correlacionadas y asociadas con la prueba R de Pearson y R2 a través de un modelo de regresión lineal. Se estableció una significancia de un valor p<0.05. Los resultados muestran una relación significativa entre las variables de composición corporal con la prueba de abdominales (p < ,001), flexibilidad (p=,019), salto horizontal (p < ,001), 20 metros planos (p < ,001), flexiones de brazos (p < ,001), Vo2máx (p < ,001), fuerza de prensión manual en mano dominante (p < ,001) y mano no dominante (p < ,001). El porcentaje de masa grasa es la variable que presenta mayor nivel de relación con las capacidades físicas. The objective of this study was to determine the level of relationship between anthropometric characteristics, body composition, and physical capacities in schoolchildren from the Quintero commune. 135 students aged 11.07 ± 2.3 years participated in the research. Anthropometric variables were measured using the ISAK protocol. The BMI weight / height2, fat percentage with the Slaughter formula, and the conicity index with the Valdez formula. An adaptation of the EUROFIT® battery was used to measure physical capacities. The variables were correlated and associated with Pearson's R test and R2 through a linear regression model. The significance level was set at p <0.05. The results show a significant relationship between the variables of body composition with the abdominal test (p <.001), flexibility (p = 0.019), horizontal jump (p <.001), 20 meters flat (p <.001), push-ups (p <.001), Vo2máx (p <.001), handgrip strength in dominant hand (p <.001) and non-dominant hand (p <.001). The percentage of fat mass is the variable that has the highest level of relationship with physical capacities.

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Boryi Alexander Becerra-PatiñoBoryi Alexander Becerra-Patiño
Boryi Alexander Becerra-Patiño
ABAura Daniela Montenegro- Bonilla
Aura Daniela Montenegro- Bonilla
JAJorge Eduardo Olivares Arancibia
Jorge Eduardo Olivares Arancibia
Sam Hernández-JañaSam Hernández-Jaña
Sam Hernández-Jaña
RYRodrigo Yáñez-Sepúlveda
Rodrigo Yáñez-Sepúlveda
José Francisco López-GilJosé Francisco López-Gil
José Francisco López-Gil
Background: This sport involves the integration of various capabilities and mechanisms, including cognitive, physiological, and biomechanical components, that allow the athlete to perform in competition. However, to date, no systematic review has analyzed the indicators that are decisive for sports performance in Bicycle Motocross (BMX). The objective of this work was to carry out a systematic review of the performance variables in BMX and establish recommendations for researchers and trainers. Materials and Methods: The following databases were consulted: PubMed, Scopus, and Web of Science. This systematic review uses the guidelines of the PRISMA statement and the guidelines for performing systematic reviews in sports sciences. The search approach, along with the selection criteria and additional details, were previously noted in the prospective registry (INPLASY202480036). The quality of the evidence was evaluated via the PEDro scale. Results: The 21 studies that make up the sample of this systematic review have a total sample of 287 athletes. However, in the studies analyzed, there are five main categories for the study of performance in BMX: (i) physiological profile and BMX and bicarbonate; (ii) BMX and physical characteristics (power, speed, and sprint); (iii) translation and rotational acceleration and systems and implements; (iv) psychological variables; and (v) skills and techniques. Conclusions: This systematic review provides convincing evidence regarding the influence of several factors that can determine performance in BMX, including Pmax, cadence, neuromuscular capacity, feedback and cognitive training, accelerometry and video analysis, anaerobic–aerobic relationships, physical conditioning, strength, and speed.