Effects of a Low Dose of Orally Administered Creatine Monohydrate on Post-Fatigue Muscle Power in Young Soccer Players.

The use of creatine monohydrate (Cr) in professional soccer is widely documented. However, the effect of low doses of Cr on the physical performance of young soccer players is unknown. This study determined the effect of a low dose of orally administered Cr on muscle power after acute intra-session fatigue in young soccer players. Twenty-eight young soccer players (mean age = 17.1 ± 0.9 years) were randomly assigned to either a Cr (n = 14, 0.3 g·kg-1·day-1 for 14 days) or placebo group (n = 14), using a two-group matched, double-blind, placebo-controlled design. Before and after supplementation, participants performed 21 repetitions of 30 m (fatigue induction), and then, to measure muscle power, they performed four repetitions in half back squat (HBS) at 65% of 1RM. Statistical analysis included a two-factor ANOVA (p ˂ 0.05). Bar velocity at HBS, time: p = 0.0006, ŋp2 = 0.22; group: p = 0.0431, ŋp2 = 0.12, time × group p = 0.0744, ŋp2 = 0.02. Power at HBS, time: p = 0.0006, ŋp2 = 0.12; group: p = 0.16, ŋp2 = 0.06, time × group: p = 0.17, ŋp2 = 0.009. At the end of the study, it was found that, after the induction of acute intra-session fatigue, a low dose of Cr administered orally increases muscle power in young soccer players.

Environmental pollution and health in Chilean older adults: Impact on quality of life and functional autonomy.

Background and Aims: Due to increased urbanization and industry, environmental pollution is a serious public health concern. Globally, the quality of life is particularly lowered by exposure to high amounts of particulate matter (PM). Chile has five industrial zones with high pollution levels, called "sacrifice zones." However, the effect of polluted air on the quality of life and functional autonomy (FA) of older people living in industrial zones with high pollution levels is unknown. Therefore, this study aimed to determine the quality of life and FA differences between Chilean older women (OW) living in areas with lower and higher PM levels. Materials and Methods: Seventy-two OW volunteered for this study. The sample was divided into Zone 1 (PM2.5 ≤ 15 µg/m3, n = 36) and Zone 2 (PM2.5 > 15 µg/m3, n = 36). The variables were quality of life-assessed through the SF-36v2.0 questionnaire, and FA-assessed through the GDLAM protocols. Differences between zones were tested by Student's t-test and Mann-Whitney test, both for independent samples (p < 0.05). Results: All eight dimensions of quality of life were lower in Zone 2, of which the role emotional (RE) showed significant differences between zones (p < 0.05). Performance on the GDLAM protocols and the FA index were lower in Zone 2 (p ˃ 0.05). Conclusion: OW in Zone 2 showed lower quality of life and FA. PM could affect the older population's physical and mental health and, therefore, the quality of life.

Muscle Quality Index is inversely associated with psychosocial variables among Chilean adolescents.

A good muscle quality index (MQI) may have an inverse relationship with psychosocial variables of depression, anxiety, and stress in adolescents. Unfortunately, little scientific evidence has related MQI to psychosocial variables in this population. Therefore, this research aimed to determine the relationship between the MQI and psychosocial variables of depression, anxiety, and stress in Chilean adolescents. In this quantitative correlational design study, sixty adolescents participated voluntarily (mean ± standard deviation [SD]: age 15.11 ± 1.78 years). Anthropometric parameters, prehensile strength, MQI, and psychosocial variables were evaluated. The results showed that adolescents with high levels of MQI presented lower levels of depression (7.50 ± 6.06 vs. 10.97 ± 5.94), anxiety (5.64 ± 4.81 vs. 9.66 ± 5.12), and stress (6.79 ± 5.09 vs. 10 ± 5.58), in addition to reported lower abdominal obesity (WtHR, 0.47 ± 0.07 vs. 0.52 ± 0.07) than those with low levels of MQI. The group with high levels of MQI reported a higher prevalence of nonanxiety (81.3%, p = 0.031) and a lower prevalence of abdominal obesity (55.8%, p = 0.023). Likewise, a significant inverse association was evidenced between MQI and depression (ß; -6.18, 95% CI; -10.11: -2.25, p = 0.003), anxiety (ß; -6.61, 95% CI; -9.83: -3.39, p < 0.001) and stress (ß; -4.90, 95% CI; -8.49: -1.32 p = 0.008). In conclusion, the results suggest that high levels of MQI are associated with a higher prevalence of nonanxiety in adolescents and a significant inverse association between MQI and levels of depression, anxiety, and stress.

Effects of acute beta-alanine supplementation on post-exertion rating of perceived exertion, heart rate, blood lactate, and physical performance on the 6-minute race test in middle-distance runners / Efectos de la suplementación aguda con beta-alanina sobre el índice de esfuerzo percibido, la frecuencia cardíaca y el lactato sanguíneo posesfuerzo, y el rendimiento físico en la prueba de carrera de 6 minutos en corredores de media distancia

Background: the use of beta-alanine (BA) to increase physical performance in the heavy-intensity domain zone (HIDZ) is widely documented. However, the effect of this amino acid on the post-exertion rating of perceived exertion (RPE), heart rate (HR), and blood lactate (BL) is still uncertain. Objectives: a) to determine the effect of acute BA supplementation on post-exertion RPE, HR, and BL in middle-distance athletes; and b) todetermine the effect of acute BA supplementation on physical performance on the 6-minute race test (6-MRT). Material and methods: the study included 12 male middle-distance athletes. The design was quasi-experimental, intrasubject, double-blind& crossover. It had two treatments (low-dose BA [30 mg·kg-1] and high-dose BA [45 mg·kg-1]) and a placebo, 72 hours apart. The effect of BA was evaluated at the end of the 6-MRT and post-exertion. The variables were RPE, HR and BL, and 6-MRT (m) distance. The statistical analysis included a repeated-measures ANOVA (p < 0.05). Results: the analysis evidenced no significant differences at the end of 6-MRT for all variables (p < 0.05). However, both doses of BA generated a lower post-exertion RPE. The high dose of BA caused significant increases in post-exertion BL (p < 0.05). Conclusion: acute supplementation with BA generated a lower post-exertion RPE. This decrease in RPE and the post-exertion BL increase could be related to an increase in physical performance in HIDZ. (AU)

Introducción: el uso de beta-alanina (BA) para aumentar el rendimiento físico en zonas con dominio de alta intensidad (HIDZ) está ampliamente documentado. Sin embargo, el efecto de este aminoácido sobre el índice de esfuerzo percibido (RPE), la frecuencia cardíaca (HR) y el lactato sanguíneo (BL) aún es incierto. Objetivos: a) determinar el efecto de la suplementación aguda de BA sobre el RPE, la HR y el BL posesfuerzo; y b) además del rendimiento en la prueba de carrera de 6 minutos (6-MRT), en atletas de media distancia. Material y métodos: el estudio incluyó a 12 atletas masculinos de media distancia. El diseño fue cuasiexperimental, intrasujeto, doble ciego y cruzado. Incluyó dos tratamientos (BA en dosis baja [30 mg·kg-1] y BA en dosis alta [45 mg·kg-1]) y placebo, con 72 horas de diferencia. El efecto de BA se evaluó al final de los 6-MRT y posesfuerzo. Las variables fueron RPE, HR y BL, y distancia en 6-MRT (m). El análisis estadístico incluyó un ANOVA de medidas repetidas (p < 0,05). Resultados: el análisis no evidenció diferencias significativas al final de los 6-MRT para todas las variables (p > 0,05). Sin embargo, ambasdosis de BA generaron un menor RPE posesfuerzo. La dosis alta de BA generó incrementos significativos en el BL posesfuerzo (p < 0,05). Conclusión: la suplementación aguda con BA generó un menor RPE posesfuerzo. Esta disminución del RPE y el aumento en el BL posesfuerzo podrían estar relacionados con un aumento del rendimiento físico en HIDZ. (AU)

Effects of acute beta-alanine supplementation on post-exertion rating of per-ceived exertion, heart rate, blood lactate, and physical performance on the 6-minute race test in middle-distance runners.

Introduction: Background: the use of beta-alanine (BA) to increase physical performance in the heavy-intensity domain zone (HIDZ) is widely documented. However, the effect of this amino acid on the post-exertion rating of perceived exertion (RPE), heart rate (HR), and blood lactate (BL) is still uncertain. Objectives: a) to determine the effect of acute BA supplementation on post-exertion RPE, HR, and BL in middle-distance athletes; and b) to determine the effect of acute BA supplementation on physical performance on the 6-minute race test (6-MRT). Material and methods: the study included 12 male middle-distance athletes. The de-sign was quasi-experimental, intrasubject, double-blind & crossover. It had two treat-ments (low-dose BA [30 mg·kg-1] and high-dose BA [45 mg·kg-1]) and a placebo, 72 hours apart. The effect of BA was evaluated at the end of the 6-MRT and post-exertion. The variables were RPE, HR and BL, and 6-MRT (m) distance. The statistical analysis included a repeated-measures ANOVA (p < 0.05). Results: the analysis evidenced no significant differences at the end of 6-MRT for all variables (p ˃ 0.05). However, both doses of BA generated a lower post-exertion RPE. The high dose of BA caused significant increases in post-exertion BL (p ˂ 0.05). Conclusion: acute supplementation with BA generated a lower post-exertion RPE. This decrease in RPE and the post-exertion BL increase could be related to an increase in physical performance in HIDZ.

Introducción: Introducción: el uso de beta-alanina (BA) para aumentar el rendimiento físico en zo-nas con dominio de alta intensidad (HIDZ) está ampliamente documentado. Sin em-bargo, el efecto de este aminoácido sobre el índice de esfuerzo percibido (RPE), la frecuencia cardíaca (HR) y el lactato sanguíneo (BL) aún es incierto. Objetivos: a) determinar el efecto de la suplementación aguda de BA sobre el RPE, la HR y el BL posesfuerzo; y b) además del rendimiento en la prueba de carrera de 6 mi-nutos (6-MRT), en atletas de media distancia. Material y métodos: el estudio incluyó a 12 atletas masculinos de media distancia. El diseño fue cuasiexperimental, intrasujeto, doble ciego y cruzado. Incluyó dos trata-mientos (BA en dosis baja [30 mg·kg-1] y BA en dosis alta [45 mg·kg-1]) y placebo, con 72 horas de diferencia. El efecto de BA se evaluó al final de los 6-MRT y posesfuerzo. Las variables fueron RPE, HR y BL, y distancia en 6-MRT (m). El análisis estadístico in-cluyó un ANOVA de medidas repetidas (p < 0,05). Resultados: el análisis no evidenció diferencias significativas al final de los 6-MRT pa-ra todas las variables (p ˃ 0,05). Sin embargo, ambas dosis de BA generaron un menor RPE posesfuerzo. La dosis alta de BA generó incrementos significativos en el BL poses-fuerzo (p ˂ 0,05). Conclusión: la suplementación aguda con BA generó un menor RPE posesfuerzo. Esta disminución del RPE y el aumento en el BL posesfuerzo podrían estar relacionados con un aumento del rendimiento físico en HIDZ.

Variable Resistance-An Efficient Method to Generate Muscle Potentiation: A Systematic Review and Meta-Analysis.

Variable resistance (VR) is a methodology that has shown good results in developing muscular strength and power. However, no updated information relates to the use of VR as an activation to trigger post-activation performance enhancement (PAPE). The primary objective of this systematic review and meta-analysis was to review and qualitatively describe studies published between 2012 and 2022 that used VR to generate PAPE in muscle power-dominant sports. The secondary objective was to calculate the effect size of the different power outcomes reported in the selected studies. The search was designed following the PRISMA® guidelines for systematic reviews and meta-analyses and performed in the Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2012 and 2022. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the throwing speed, time in sprint tests, and jump height. The analysis was conducted with a pooled standardized mean difference (SMD) through a Hedges' g test (95% CI). Twenty-two studies were included in the systematic review and ten in the meta-analysis, revealing a trivial effect for throwing speed (SMD = 0.06; CI = 95%: -0.23-0.35; p = 0.69), a small effect for the time in sprint tests (SMD = -0.37; CI = 95%: -0.72--0.02; p = 0.04), and a moderate effect for jump height (SMD = 0.55; CI = 95%: 0.29-0.81; p ˂ 0.0001). All forms of VR used for neuromuscular activation effectively triggered PAPE. Specifically, the results showed that activation with VR generates performance increases in time, in sprint tests and jump height, and a trivial effect in throwing tests (speed and distance).

Acute Supplementation with Beta-Alanine Improves Performance in Aerobic-Anaerobic Transition Zones in Endurance Athletes.

To determine the acute effect of low and high-dose BA trials on maximal aerobic speed (MAS) in endurance athletes. We hypothesized that high doses of BA have a greater effect than low doses, both compared to baseline.Twelve male endurance athletes volunteered for the study (age = 21.8 ± 2.37 years, weight = 69.8 ± 4.36 kg, height = 174 ± 5.45 cm, maximal oxygen uptake = 59.6 ± 3.77 mLO2·kg-1·min-1). The experimental design applied was randomized cross-over, double-blind. Treatment included three 6-minute run tests (6-MRT), the first as a baseline, then randomized 6-MRT with low (30 mg·kg-1) and high (45 mg·kg-1) dose BA trials. The 6-MRTs were separated by 72 hours. The main variable of the study was the distance (m) performed in the 6-MRT. Differences between tests were established through ANOVA and Tukey's multiple comparison tests (p < 0.05).The analysis showed significant differences between baseline and both doses (p < 0.001). No significant differences were observed between low and high-dose BA trials (p > 0.05).Both 30 and 45 mg·kg-1 of BA increased physical performance at maximal aerobic speed in endurance athletes. The acute intake formats described in the present investigation may be helpful for endurance athletes training and competing in aerobic-anaerobic transition zones.

Effects of Training with Different Modes of Strength Intervention on Psychosocial Disorders in Adolescents: A Systematic Review and Meta-Analysis.

Physical exercise has a positive impact on anxiety and depression. However, the evidence that associates strength training with a decrease in adolescents' psychosocial disorders is scarce. Consequently, the objective was to analyze the effects of training with different modes of strength intervention on anxiety, stress, and depression in adolescents. The search was designed according to PRISMA®. We searched WoS, Scopus, SPORTDiscus, PubMed, and MEDLINE (2010-2020). Methodological quality and risk of bias were assessed with the Cochrane Collaboration. The analysis was carried out with a standardized mean difference (SMD) pooled using the Hedges g test (95% CI). The Main Outcome Measures were: anxiety, stress, and depression in adolescents post strength training. Nine studies were included in the systematic review and seven in the meta-analysis. These studies showed a large and significant effect of strength training on anxiety (SMD = -1.75; CI = 95%: -3.03, -0.48; p = 0.007) and depression (SMD = -1.61; CI = 95%: -2.54, -0.67, p = 0.0007). In conclusion, training with different modes of strength intervention have shown control over anxiety and depression in adolescents. However, conventional strength training seems to have better results than other modes of strength intervention.

Sleep Quality in Chilean Professional Soccer Players.

Recent research has shown that good sleep quality has a positive effect on physical performance. However, sleep quality in Chilean professional soccer players is unknown. The purpose of this study was to determine sleep quality in Chilean professional soccer players. It was a cross-sectional, explanatory study with observable variables. The sample consisted of 94 Chilean male soccer players belonging to four professional clubs. The main variable was the Sleep Quality Index, evaluated through the Pittsburgh questionnaire (Spanish version). After estimating sleep quality individually, the four professional soccer clubs' comparison was performed through a one-factor ANOVA. The Pearson test was used to relate the questionnaire variables; the significance level was p < 0.05. In the global analysis of the Pittsburgh Sleep Quality Index, a value of 4.75 ± 2.29 on a scale of 0-21 was observed, with no significant differences between the clubs evaluated (p > 0.05). Based on the results obtained, Chilean male professional soccer players present good sleep quality. However, the high values of "sleep latency" and "sleep disturbances" are indicators that should be worked on by the multidisciplinary team of each professional club. They should develop strategies to improve sleep hygiene, encourage good sleep, and fall asleep efficiently.

Effects of a period without mandatory physical training on maximum oxygen uptake and anthropometric parameters in naval cadets.

The effects of a period without physical training on the civilian population are well established. However, no studies show the effects of a period without mandatory physical training on maximum oxygen uptake (VO2 max) and anthropometric parameters in naval cadets. This study aimed to investigate changes in VO2 max and anthropometric parameters after 12 weeks without mandatory physical training in naval cadets. The sample was 38 healthy and physically active naval cadets. The measured variables, including VO2 max and anthropometric parameters, were evaluated through the 12-minute race test (12MRT) and the somatotype. Both variables had a separation of 12 weeks without mandatory physical training. A t-test for related samples was used to evidence changes between the test and post-test; effect size was calculated through Cohen's d-test. Distance in 12MRT and VO2 max showed significant decreases at the end of 12 weeks without mandatory physical training (p < 0.001). Likewise, the tricipital skinfold thickness and the endomorphic component showed significant increases (p < 0.05). 12 weeks without mandatory physical training significantly reduces the VO2 max in naval cadets. Simultaneously, the same period without physical training increases both the tricipital skinfold thickness and the endomorphic component in this population.

A qualitative scale of the 6-minute race test to evaluate maximum aerobic speed in physically active people from 18 to 25 years.

[Purpose] To create a qualitative scale for the 6-minute race test in physically active participants from 18 to 25 years old. [Participants and Methods] The sample was 299 healthy participants (254 males and 45 females). All the participants were instructed to perform the greatest possible distance in the 6-minute race test. To evaluate the reliability of the 6-minute race test, 30 participants performed the 6-minute race test for a second time. The variable was distance in meters. The qualitative scale was constructed with the percentiles <25, 50, 75, 90 and >90 for the criteria poor, fair, good, very good and excellent, respectively; the reliability was calculated with the coefficient of variation, intra-class correlation coefficient and the standard error of the mean. [Results] In the 6-minute race test, the mean was 1,607 and 1,364 meters for males and females, respectively. The coefficient of variation=4.08%, intra-class correlation coefficient=0.93 and standard error of the mean=11.46. [Conclusion] The creation of the qualitative scale of the 6-minute race test allows us to evaluate and classify the level and increase of maximum aerobic speed in physically active participants from 18 to 25 years old.

Fuerza prensil como factor predictor de Ansiedad-Rasgo en estudiantes universitarias / Grip strength as a predictor of Trait-Anxiety in university students

Introducción: Investigaciones han determinado que la implementación de programas de actividad física mejora la salud mental. Sin embargo, aún existen dudas sobre la relación entre fuerza muscular y la presencia de trastornos psicosociales como ansiedad y estrés en la población universitaria. Objetivo: Relacionar la condición física, específicamente la fuerza prensil, con la presencia de Ansiedad-Rasgo en estudiantes mujeres. Materiales y métodos: Investigación empírica con estrategia asociativa predictiva, con un diseño predictivo transversal. La muestra fue de 30 estudiantes mujeres de pregrado. Las variables físicas predictoras evaluadas fueron antropometría, fuerza prensil y consumo máximo de oxígeno, mientras que la Ansiedad-Rasgo se midió por medio del Cuestionario de Ansiedad Estado Rasgo (STAI). Se realizó análisis estadístico con una regresión logística ordinal entre las variables físicas predictoras y nivel de Ansiedad-Rasgo. Resultados: Se evidenció que sólo la fuerza prensil fue estadísticamente significativa (p=0,033). Este análisis expresado en Odds Ratio, asume un 74,36% de probabilidad que a un menor nivel de fuerza prensil, mayor presencia de Ansiedad-Rasgo. Conclusiones: La fuerza prensil, además de ser un parámetro físico que permite detectar riesgo cardiovascular y patologías asociadas, también debería ser considerada en la determinación de alteraciones en salud mental.

Introduction: Research has revealed that the implementation of physical activity programs improves mental health. However, there are still doubts about the relationship between muscle strength and the presence of psychosocial disorders such as anxiety and stress in the university student population. Objective: To study the association of a physical condition (grip strength) and the presence of Trait-Anxiety in female students. Materials and methods: An empirical research with a predictive associative strategy was conducted on a sample of 30 female undergraduate students. The predictor physical variables assessed were anthropometry, grip strength, and maximum oxygen consumption. Trait-Anxiety was evaluated using the State-Trait Anxiety Inventory (STAI). Statistical analysis was performed through ordinal logistic regression between predictor physical variables and level of Trait-Anxiety. Results: Only grip strength was statistically significant (p=0.033). This analysis, expressed as Odds Ratio, assumes a 74.36% probability that the lower level of grip strength, the greater chances of having Trait-Anxiety. Conclusions: Grip strength is not only a physical parameter to detect cardiovascular risks and associated pathologies, but also it should be used to identify mental health disorders.

Validity and reliability of the Muscular Fitness Test to evaluate body strength-resistance

INTRODUCTION: In periods of confinement, people cannot be assessed in training centers. Therefore, it is essential to have valid and reliable tests to evaluate physical capacities remotely and with their respective valuation tables. OBJECTIVE: To determine the validity and reliability of the Muscular Fitness Test (MFT) to evaluate the body strength-resistance with self-loading in healthy young adults. Secondly, to create qualitative scales to evaluate the different levels of this physical capacity. MATERIAL AND METHODS: 489 participants performed the MFT (test), and 77 performed it twice (re-test). The MFT included 60seconds (s) of sit-ups, push-ups, deep squats, and burpees, always in that order, with a micropause of 10s. The validity of the MFT was evaluated with the final heart rate (FHR), % of the reserve HR (%) and Rating of Perceived Exertion (RPE); the reliability included the Coefficient of Variation (CV), Intra-Class Correlation Coefficient (ICC) and the standard error of the mean (SEM) (p < 0.05). The qualitative scales were constructed with the percentiles ≤25: poor, ≤50: fair, ≤75: good, ≤90: very good, and >90: excellent. RESULTS: Participants performed 91.7±26.5 total repetitions, with a FHR of 172.7bpm (81.7%) and RPE of 8.1; CV=2.81%, ICC=0.97 and SEM=0.77 (p < 0.001). CONCLUSION: MFT proved to be valid and reliable to assess self-loaded body strength-resistance in healthy young adults. The creation of the MFT qualitative scales allows evaluating the level of body strength-resistance in this population

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Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis.

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I2 = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I2 = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I2 = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

Efectos de un programa de Zumba(R) sobre niveles de ansiedad-rasgo, ansiedad-estado y condición física en estudiantes universitarias chilenas / Effects of a Zumba(R) program over levels of anxiety-trait, anxiety-state and physical condition in Chilean university students / Efeito de um programa Zumba(R) nos níveis de ansiedade-traço, ansiedade-estado e condição física em estudantes universitários chilenos

Diversas investigaciones han determinado que la implementación de programas de actividad física mejora la salud mental. Sin embargo, aún existen dudas sobre los beneficios de los programas Zumba® en la población que lo practica. El propósito de este estudio fue determinar los efectos de un programa de ejercicio físico basado en Zumba®, sobre los niveles de ansiedad-rasgo y ansiedad-estado en estudiantes universitarias chilenas. Investigación cuantitativa cuasi-experimental, con una muestra de 22 estudiantes mujeres de pregrado (grupo experimental = 10 y grupo control = 12). Las variables fueron: ansiedad-rasgo (A-R) y ansiedad-estado (A-E), además de variables físicas como antropometría, consumo máximo de oxígeno (VO2máx) y fuerza prensil. El análisis estadístico se realizó a través de un ANOVA mixto para todas las variables. En nivel de significancia fue de p < 0,05. Los resultados evidenciaron cambios no significativos en los distintos niveles de A-R ni A-E luego de la aplicación del programa de Zumba® (p > 0,05), tampoco hubo cambios en las otras variables de estudio (p > 0,05). Al término de la intervención, no se observaron efectos del programa de Zumba® sobre los distintos niveles de A-R y A-E, como tampoco sobre variables antropométricas, VO2máx ni fuerza prensil

Several investigations have specified that the implementation of physical activity programs improve mental health. However, there are still doubts about the benefits on the population taking part in Zumba® programs. The purpose of this study was to determine the effects of a Zumba® based working out program on the levels of anxiety-trait and anxiety-state in Chilean university students. It was a quantitative, cuasi-experimental study with a sample of 22 undergraduate female students (experimental group = 10 and control group = 12). The variables were anxiety-trait (A-T) and anxiety-state (A-S), in addition to physical variables, such as anthropometry, maximum oxygen consumption (VO2max) and grip strength. A statistical analysis was performed through a mixed ANOVA. The level of significance for all analyses was p < 0.05. The results showed no significant changes in the different levels of A-T or A-S (p > 0.05), there were also no changes in the other variables (p > 0.05). At the end of the intervention, no effects of the Zumba® program were observed on the different levels of A-T and A-S, nor on anthropometric variables, VO2max or grip strength

Várias investigações determinaram que a implementação de programas de atividade física melhora a saúde mental. No entanto, ainda existem dúvidas sobre os benefícios dos programas Zumba® na população que pratica. O objetivo deste estudo foi determinar os efeitos de um programa de exercícios físicos baseado no Zumba®, sobre níveis de Ansiedade-Traço e Ansiedade-Estado em estudantes universitários chilenos. Pesquisa quantitativa quase experimental, com uma amostra de 22 estudantes do sexo feminino (grupo experimental [GE] = 10 e grupo controle [GC] = 12). As variáveis foram: Ansiedade-Traço (A-T) e Ansiedade-Estado (A-E), ambas avaliadas pelo STAI Trait State Anxiety Questionnaire, além de variáveis físicas como antropometria, consumo máximo de oxigênio (VO2máx) e força pré-trilateral. A análise estatística foi realizada através de uma ANOVA mista para todas as variáveis e uma tabela de contingência por meio do Qui-Quadrado de Pearson para os diferentes níveis de A-T e A-E. O nível de significância para todas as análises foi de p <0,05. Os resultados não mostraram alterações significativas em todas as variáveis do estudo após a aplicação do programa Zumba® (p> 0,05); também não houve diferenças nos diferentes níveis de A-T ou A-E (p> 0,05). Ao final da intervenção, não foram observados efeitos do programa Zumba® sobre diferentes níveis de A-R e A-E, nem nas variáveis antropométricas, VO2máx ou força preênsil

Effects of different methods of strength training on indicators of muscle fatigue during and after strength training: a systematic review

Abstract Introduction: The development of strength has shown to be beneficial to sports performance and health. However, during strength training, they also produce alterations in muscle fatigue indicators, leading to a decrease in the ability to generate strength. Despite this, there is still not enough knowledge about the levels of muscle fatigue generated by different methods of strength training and how this information can be integrated into sports planning. Review and analyze the studies existing between January 2009 and January 2019 that have used indicators of muscle fatigue established in the search terms during and after strength training as measurement variables. Evidence acquisition: The study corresponds to a systematic review of previously published studies, following the PRISMA model. Articles published between 2009 and 2019 that measured muscle fatigue indicators during and after strength training were evaluated. The electronic search was conducted through Web of Science, Scopus, Sport Discus, PubMed, and Medline. We included all articles that used a strength protocol and also measured indicators of muscle fatigue and its possible effect on physical performance. Evidence synthesis: A total of 39 articles were found, which were stratified according to the protocol used: (i) plyometric training, (ii) Bodypump® training, (iii) occlusion training, (iv) variable resistance training, (v) conventional strength training, (vi) eccentric strength training, (vii) rest times in strength training and (viii) concurrent training. Conclusion: At the end of the systematic review, it was shown that the different training methodologies for strength development generate increases in muscle fatigue indicators, and the increase generated in the different muscle fatigue indicators depends both on the methodology used and on the type of population, sex, level of training and type of sport. The most-reported indicators are [La], HR and RPE, DOM, MR variation, and ammonium.

Efecto de la suplementación de L-arginina y L-citrulina sobre el rendimiento físico: una revisión sistemática / The effect of supplementation with L-arginine and L-citrulline on physical performance: a systematic review

Introducción: los aminoácidos L-arginina (L-arg) y L-citrulina (L-citr) se han utilizado dentro de la nutrición deportiva y se cree que ejercen un efecto sobre el rendimiento físico. Sin embargo, la información existente es variada y poco concluyente. Objetivo: revisar y analizar la evidencia científica existente dentro de los últimos diez años que relacionó los efectos de la suplementación con L-arg y L-citr sobre el rendimiento físico. Material y método: el estudio corresponde a una revisión sistemática de estudios previamente publicados, siguiendo el modelo PRISMA. Se evaluaron artículos publicados entre los años 2008 y 2018 que relacionaron la suplementación de L-arg y L-citr sobre el rendimiento físico. La búsqueda electrónica se realizó a través de Web of Science, Scopus, Sport Discus, PubMed, Medline. Se incluyeron todos los artículos que utilizaron un protocolo de suplementación de estos aminoácidos por separado o en conjunto. Resultados: se encontraron 38 artículos, los que se estratificaron según el protocolo utilizado: a) suplementación con L-arg (n = 19); b) suplementación con L-arg y L-citr (n = 1); y c) suplementación con L-citr (n = 18), tanto de corta duración como prolongada. Conclusión: existe evidencia de que la L-citr puede funcionar mejor como ayuda ergogénica que la L-arg sobre el rendimiento físico, ya que la L-citr mostró un efecto positivo sobre la percepción subjetiva del esfuerzo y el dolor muscular, además de una disminución en las concentraciones de lactato y una disminución del tiempo en pruebas máximas. Sin embargo, aún falta evidencia para establecer la dosis de L-citr beneficiosa para el rendimiento físico

Introduction: the amino acids L-arginine (L-arg) and L-citrulline (L-citr) have been used in sports nutrition, and it is believed that they have an effect on physical performance. However, current information is varied and inconclusive. Objective: to review and analyze the scientific evidence in the last ten years, which reflects a connection between the effect of L-arg and L-citr supplementation and physical performance. Material and method: this study is a systematic review of articles previously published, following the PRISMA model. Those articles published between 2008 and 2018 that connected the effect of L-arg and L-citr supplementation with physical performance were analyzed. The electronic search was performed on Web of Science, Scopus, Sport Discus, PubMed, and Medline. All articles using a supplementation protocol with these amino acids, separately or in groups, were selected. Results: a total of 38 articles were found, which were stratified according to the established protocol: a) supplementation with L-arg (n = 19); b) supplementation with L-arg and L-citr (n = 1); and c) supplementation with L-citr (n = 18), whether of short or prolonged duration. Conclusion: there is evidence that L-citr works better as ergogenic than L-arg does on physical performance, since L-citr showed a positive effect on the rate of perceived exertion and muscular pain, in addition to a decrease in lactate concentrations and time in maximum tests. However, there is not enough evidence to establish a beneficial L-citr dosage for physical performance

[The effect of supplementation with L-arginine and L-citrulline on physical performance: a systematic review]. / Efecto de la suplementación de L-arginina y L-citrulina sobre el rendimiento físico: una revisión sistemática.

INTRODUCTION: Introduction: the amino acids L-arginine (L-arg) and L-citrulline (L-citr) have been used in sports nutrition, and it is believed that they have an effect on physical performance. However, current information is varied and inconclusive. Objective: to review and analyze the scientific evidence in the last ten years, which reflects a connection between the effect of L-arg and L-citr supplementation and physical performance. Material and method: this study is a systematic review of articles previously published, following the PRISMA model. Those articles published between 2008 and 2018 that connected the effect of L-arg and L-citr supplementation with physical performance were analyzed. The electronic search was performed on Web of Science, Scopus, Sport Discus, PubMed, and Medline. All articles using a supplementation protocol with these amino acids, separately or in groups, were selected. Results: a total of 38 articles were found, which were stratified according to the established protocol: a) supplementation with L-arg (n = 19); b) supplementation with L-arg and L-citr (n = 1); and c) supplementation with L-citr (n = 18), whether of short or prolonged duration. Conclusion: there is evidence that L-citr works better as ergogenic than L-arg does on physical performance, since L-citr showed a positive effect on the rate of perceived exertion and muscular pain, in addition to a decrease in lactate concentrations and time in maximum tests. However, there is not enough evidence to establish a beneficial L-citr dosage for physical performance.

INTRODUCCIÓN: Introducción: los aminoácidos L-arginina (L-arg) y L-citrulina (L-citr) se han utilizado dentro de la nutrición deportiva y se cree que ejercen un efecto sobre el rendimiento físico. Sin embargo, la información existente es variada y poco concluyente. Objetivo: revisar y analizar la evidencia científica existente dentro de los últimos diez años que relacionó los efectos de la suplementación con L-arg y L-citr sobre el rendimiento físico. Material y método: el estudio corresponde a una revisión sistemática de estudios previamente publicados, siguiendo el modelo PRISMA. Se evaluaron artículos publicados entre los años 2008 y 2018 que relacionaron la suplementación de L-arg y L-citr sobre el rendimiento físico. La búsqueda electrónica se realizó a través de Web of Science, Scopus, Sport Discus, PubMed, Medline. Se incluyeron todos los artículos que utilizaron un protocolo de suplementación de estos aminoácidos por separado o en conjunto. Resultados: se encontraron 38 artículos, los que se estratificaron según el protocolo utilizado: a) suplementación con L-arg (n = 19); b) suplementación con L-arg y L-citr (n = 1); y c) suplementación con L-citr (n = 18), tanto de corta duración como prolongada. Conclusión: existe evidencia de que la L-citr puede funcionar mejor como ayuda ergogénica que la L-arg sobre el rendimiento físico, ya que la L-citr mostró un efecto positivo sobre la percepción subjetiva del esfuerzo y el dolor muscular, además de una disminución en las concentraciones de lactato y una disminución del tiempo en pruebas máximas. Sin embargo, aún falta evidencia para establecer la dosis de L-citr beneficiosa para el rendimiento físico.

Behavior of creatine kinase in a variable resistance session.

[Purpose] The purpose of this study was to determine the behavior of creatine kinase before and after the execution of a pre-activation protocol with intra-set variable resistance in order to generate post-activation potentiation in female athletes. [Participants and Methods] Six sprint women were part of the study. The study had a quasi-experimental intra-participant design. The experimental condition included a pre-activation with intra-set variable resistance + 1 minute rest + 30-m sprint × 3. The variables were metabolic creatine kinase, total creatine kinase, and 30-m sprints. [Results] Both the experimental condition and the control condition showed an increase in creatine kinase and total creatine kinase 24 hours post-effort. Only the experimental condition showed improvement in 30-m sprints after the pre-activation with intra-set variable resistance. [Conclusion] All those sessions oriented to increasing strength levels with a pre-activation protocol through intra-set variable resistance must consider rests longer than 24 hours between sessions in order not to increase creatine kinase in female athletes significantly.

Métodos de entrenamiento propioceptivos como herramienta preventiva de lesiones en futbolistas: una revisión sistemática / Proprioceptive training methods as a tool for the prevention of injuries in soccer players: a systematic review

Introducción: Los ejercicios de propiocepción se han utilizado como método de entrenamiento para disminuir la tasa de lesiones de los jugadores de fútbol, pero no existe certeza de la cantidad de investigaciones existentes ni los resultados de estos métodos. Objetivo: Investigar cuáles fueron los métodos de entrenamientos usados para la prevención de lesiones en las extremidades inferiores en futbolistas entre los años 2008 y 2018. El objetivo secundario fue describir los resultados obtenidos en cada uno de los estudios. Material y método: El estudio corresponde a una revisión sistemática de estudios previamente publicados. Se evaluaron artículos publicados entre los años 2008 y 2018 que relacionaron ejercicios de propiocepción y prevención de lesiones. La búsqueda electrónica se realizó a través de Web of Science, Scopus, Sport Discus, PubMed, MedLine. Se incluyeron todos los artículos que utilizaron propiocepción como ejercicios para la prevención de lesiones. Resultados: Fueron encontrados 11 artículos que utilizaron ejercicios de prevención en futbolistas. Los cuales fueron estratificados según el objetivo descrito: (I) Entrenamiento propioceptivo, (II) Entrenamiento de equilibrio, (III) Entrenamiento neuromuscular y (IV) Entrenamiento de control postural. Conclusión: Al término de la revisión sistemática se hallaron programas de propiocepción, equilibrio, neuromuscular y control postural. Estos métodos de entrenamiento han demostrado tener buenos resultados en la prevención de lesiones, especialmente en rodillas y tobillos. Por lo anteriormente descrito, se precisa incluir ejercicios de prevención de lesiones en los programas de entrenamiento desarrollado por futbolistas

Introduction: Proprioceptive exercises have been used as a training method in the reduction of injuries’ rate on soccer players. However, there is no certainty about the number of researches performed or the results of these methods. Objective: Investigate out which the training methods were used in lower limbs to prevent soccer players’ injuries between 2008 and 2018. The secondary objective was to describe the results of each research. Material and method: This study is a Systematic Revision of research already published. Articles published between 2008 and 2018 that connected proprioception exercises to injury prevention were reviewed. The electronic search was performed through Web of Science, Scopus, Sport Discus, PubMed, and MedLine. All articles that presented proprioception as exercises to prevent injuries were included. Results: 11 articles were found which used exercises connected to preventive programs in soccer players. Which were stratified according to the described aim: (I) Proprioceptive program, (II) Balance training, (III) Neuromuscular training, and (IV) Posture-control training. Conclusion: Once the systematic review ended, several preventive programs were found for soccer players based on pro-prioception, balance, neuromuscular and posture-control. These training methods have proven to have good results in the prevention of injuries, especially in knees and ankles. For the above described, it is necessary to include injury prevention exercises in the training programs developed by soccer players