Effect of sit-to-stand-based training on muscle quality in sedentary adults: a randomized controlled trial.

The aim of this study was to compare the effects of sit-to-stand (STS) training programs with 5 vs. 10 repetitions on muscle architecture and muscle function in sedentary adults. Sixty participants were randomly assigned into three groups: five-repetition STS (5STS), 10-repetition STS (10STS), or a control group (CG). Participants performed three sets of five or 10 repetitions of the STS exercise three times per week for 8 weeks. Before and after 8 weeks, all groups performed ultrasound measures to evaluate muscle thickness (MT), pennation angle (PA), and fascicle length (FL), and the five-repetition STS test to estimate the relative STS power and muscle quality index (MQI). After 8 weeks, both experimental groups improved MQI (40-45%), relative STS power (29-38%), and MT (8-9%) (all p < 0.001; no differences between the 5STS vs. 10STS groups). These improvements in both groups resulted in differences regarding the CG, which did not present any change. In addition, only the 5STS group improved PA (15%; p = 0.008) without differences to the 10STS and CG.This suggests that STS training is time-effective and low-cost for improving muscle function and generating adaptations in muscle architecture.

Dynamometric Strength Profile of Hip Muscles in Youth Soccer Players.

BACKGROUND: Soccer is the most widely practiced sport in the world, demanding high-speed activities such as jumps, sprints and changes of direction. Therefore, having optimal levels of muscle strength improves performance and reduces the injury rate. OBJECTIVES: The objectives of our study were (i) to determine the dynamometric profile of hip muscle strength in young soccer players by position, evaluated at different isokinetic speeds, (ii) to describe the conventional and functional unilateral muscle strength ratios, (iii) to analyze the bilateral balance. METHODS: Thirty-seven male soccer players (age 17.02 ± 0.92 years) participated in the study. Strength assessment was performed with a functional electromechanical dynamometer, and concentric and eccentric strength of abductors, adductors, extensors and hip flexors were measured bilaterally at 0.5 m/s and 1 m/s. RESULTS: For eccentric right hip abduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.013) and stronger than forwards (p = 0.140). For eccentric right hip adduction at 0.5 m/s, defenders are significantly stronger than midfielders (p = 0.005) and stronger than forwards (p = 0.253), as for eccentric right hip adduction at 1 m/s, defenders are significantly stronger than midfielders (p = 0.014) and stronger than forwards (p = 0.084). There is a significant effect for the conventional strength ratio of left abduction/adduction at 1 m/s. The conventional strength ratio of forwards is significantly higher than that of defenders (p = 0.045) and higher than that of midfielders (p = 0.152). CONCLUSIONS: Concentric and eccentric hip strength values differ according to playing position.

Reliability of Isokinetic Hip Flexor and Extensor Strength Measurements in Healthy Subjects and Athletes: A Systematic Review and Meta-Analysis.

BACKGROUND: The objective of this systematic review and meta-analysis was to examine the reliability of isokinetic measurements of hip strength in flexion and extension in healthy subjects and athletes. METHODS: The databases used were Web of Science, SCOPUS, Medline and PubMed. R was used for all statistical analyses. RESULTS: Hip flexion shows moderate reliability in the supine position (ICC = 0.72; 95% CI: 0.46-0.99) and good reliability in the standing position (ICC = 0.79; 95% CI: 0.54-1.04). Hip extension shows excellent reliability in the supine position (ICC = 0.90; 95% CI: 0.85-0.96) and moderate reliability in the standing position (ICC = 0.72; 95% CI: 0.48-0.96). Flexion of 120°/s and 180°/s showed excellent reliability (ICC = 0.93; 95% CI: 0.85-1.00), (ICC = 0.96; 95% CI: 0.92-1.01). The 60°/s and 120°/s extension showed good reliability (ICC = 0.90; 95% CI: 0.82-0.98), (ICC = 0.87; 95% CI: 0.75-0.99). The 180°/s extension presented excellent reliability (ICC = 0.93; 95% CI: 0.82-1.03). CONCLUSIONS: The standing position shows good reliability for hip flexion and the supine position shows excellent reliability for hip extension, both movements have excellent reliability at velocities between 120°/s to 180°/s.

Methods of evaluating the force-velocity profile through the vertical jump in athletes: a systematic review / Métodos de evaluación del perfil fuerza-velocidad a través del salto vertical en deportistas: una revisión sistemática

Introduction: In the world of sport, the ability of humans to develop maximum muscular power (Pmax) is directly related to performance and sporting success. For this, the measurement of the force- velocity profile (F-v) plays a key role in the evaluation of the athlete. At present, there are different methodologies and technologies to assess this profile, with sprint and vertical jump being the most used forms. The objective of this review is to identify and analyze different methods and tools for assessing F-v profile through the vertical jump. Methods: A search was carried out on the following databases, PubMed, SPORTDiscus, and Web of Science, of papers published between January 2010 and August 2017. The search terms were as follows: strength, speed, profile, vertical jump, squat jump (SJ), countermovement jump (CMJ), sports, strength training, resistance training, and all possible combinations of the above. Methodological quality was assessed using the PEDro scale. Results: Nine out of a total of 254 articles met the criteria for inclusion: six of them evaluated the F-v profile using a force platform, while three used the photocell system. Analysis of their evaluation methods revealed that of the six studies using the force platform, one used the SJ as an assessment measure, two used the CMJ and three used both methods; all three studies using the photocell system used the SJ as the method of assessment. Conclusion: The instruments most often used to evaluate the F-v profile are the force platform and the photocell system. Nevertheless, other new and interesting technologies exist that are capable of evaluating the vertical jump. for example, through mobile applications

Introducción: En el mundo del deporte, la capacidad que tiene el ser humano para desarrollar la máxima potencia muscular (Pmáx) está directamente relacionada con el rendimiento y éxito deportivo. Para ello, la medición del perfil fuerza velocidad (F-v) cumple un rol clave dentro de la evaluación del deportista. En la actualidad existen diversas metodologías y tecnologías para valorar este perfil, siendo el sprint y el salto vertical las formas más utilizadas. El objetivo de esta revisión es identificar y analizar diferentes métodos e instrumentos de evaluación del perfil F-v a través del salto vertical. Método: La búsqueda se realizó en las siguientes bases de datos: PubMed, SportDiscus y Web of Science, entre enero del 2010 hasta agosto del 2017. Los términos de búsqueda fueron los siguientes; Fuerza, velocidad, perfil, salto vertical, Squat Jump (SJ), Countermovement Jump (CMJ), deportes, entrenamiento de fuerza, entrenamiento de resistencia y sus posibles combinaciones. La calidad metodológica fue evaluada a través de la escala PEDro. Resultados: Nueve de los 254 artículos encontrados cumplieron con los criterios de inclusión al estudio, de los cuales, 6 evaluaron el perfil F-v a través de una plataforma de fuerza y 3 mediante el sistema de fotocélulas. En el análisis de los métodos de evaluación, de los 6 estudios que evaluaron el perfil F-v con plataforma de fuerza, uno lo hizo a través del SJ, dos a través del CMJ y tres utilizaron ambos métodos, mientras que de los tres estudios que valoraron el perfil F-v con el sistema de fotocélulas, todos usaron el SJ como método de evaluación. Conclusión: Los instrumentos más utilizados para la evaluación del perfil F-v son; Plataforma de fuerza y fotocélulas, sin embargo, existen nuevas tecnologías capaces de evaluar el salto vertical, por ejemplo, a través de aplicaciones móviles