Vitamin D: a review on its effects on muscle strength, the risk of fall, and frailty.

Vitamin D is the main hormone of bone metabolism. However, the ubiquitary nature of vitamin D receptor (VDR) suggests potential for widespread effects, which has led to new research exploring the effects of vitamin D on a variety of tissues, especially in the skeletal muscle. In vitro studies have shown that the active form of vitamin D, calcitriol, acts in myocytes through genomic effects involving VDR activation in the cell nucleus to drive cellular differentiation and proliferation. A putative transmembrane receptor may be responsible for nongenomic effects leading to rapid influx of calcium within muscle cells. Hypovitaminosis D is consistently associated with decrease in muscle function and performance and increase in disability. On the contrary, vitamin D supplementation has been shown to improve muscle strength and gait in different settings, especially in elderly patients. Despite some controversies in the interpretation of meta-analysis, a reduced risk of falls has been attributed to vitamin D supplementation due to direct effects on muscle cells. Finally, a low vitamin D status is consistently associated with the frail phenotype. This is why many authorities recommend vitamin D supplementation in the frail patient.

Reliability of maximal grip strength measurements and grip strength recovery following a stroke.

STUDY DESIGN: Clinical measurement. PURPOSE: The test-retest reliability of maximal grip strength measurements (MGSM) is examined in subjects for 12 weeks post-stroke together with maximal grip strength recovery and the maximal-grip and upper-extremity strength measurements' relationship with capacity and performance test scores. METHODS: A Jamar dynamometer and the Motricity Index (MI) were used for strength measurements. The Chedoke Arm and Hand Activity Inventory and ABILHAND questionnaire for evaluating capacities and performances. RESULTS: MGSM were reliable (Intraclass Correlation Coefficients = 0.97-0.99, Minimal Detectable Differences = 2.73-4.68 kg). Among the 34 participants, 47% did not have a measurable grip strength one week post-stroke but 50% of these recovered some strength within the first eight weeks. The MGSM and MI scores were correlated with scores of tests of capacity and performance (Spearman's Rank Correlation Coefficients = 0.69-0.94). CONCLUSIONS: MGSM are reliable in the first weeks after a stroke. LEVEL OF EVIDENCE: N/A.

La coordinación muscular del cuádriceps en pacientes con el síndrome del dolor femoropatelar.

Introducción: el síndrome del dolor femoropatelar es un conjunto de signos y síntomas común entre adolescentes y adultos jóvenes caracterizada por un dolor retropatelar o peripatelar en actividades tales como subir o bajar escaleras. Su etiología y métodos de tratamiento han sido ampliamente estudiados en la literatura. Se piensa que es una patología multifactorial y el tratamiento que más se prescribe es la terapia física haciendo hincapié en el fortalecimiento del cuádriceps, aunque su eficacia es aún confusa. Objetivos: esta revisión tiene como objetivo obtener información sobre la posible relación del cuádriceps como causa o consecuencia del síndrome femoropatelar y evidenciar si el tratamiento basado en el fortalecimiento de dicho músculo es efectivo para reducir los síntomas en pacientes con esta patología. Metodología: en la búsqueda bibliográfica se han revisado las bases de datos Pubmed, Cochrane y ScienceDirect de las cuales se han extraído un total de veintiún artículos siguiendo los criterios de inclusión y exclusión. Las palabras clave han sido en inglés y no han sido aceptados artículos con fecha de publicación anterior al año 2003. Resultados: se han encontrado diversidad de resultados donde el trabajo del cuádriceps y sus modalidades siguen sin estar claras respecto a sus beneficios en pacientes con síndrome del dolor femoropatelar. Aun así en la literatura revisada se observa cómo hay autores que apoyan totalmente el trabajo del cuádriceps basándose en la reducción del dolor y mejora de la funcionalidad y otros, en cambio, discrepan en algunos resultados. Conclusiones: el retardo en la activación del vasto medial oblicuo respecto al vasto lateral y la posible atrofia del vasto medial son apoyados en la literatura revisada aunque aún faltan estudios para averiguar si son causa o consecuencia del síndrome del dolor femoropatelar. La terapia física y el fortalecimiento del cuádriceps sigue siendo el tratamiento de elección para este síndrome. Respecto a las modalidades de ejercicios, tanto los ejercicios en CCC y en CCA son mencionados como beneficios para esta patología aunque no existen estudios concisos que hagan decantarse por uno de ellos. En cambio, en la realización de los ejercicios con carga o sin carga se observa que losdos tipos de ejercicios son igual de beneficiosos aunque los ejercicios con carga provocan un mayor reclutamiento en el vasto medial oblicuo.

Evaluación de la efectividad de las Técnicas de Activación Muscular® en la resolución de la fasciosis plantar en corredores habituales: ensayo clínico aleatorizado.

Pregunta clínica de investigación: ¿es efectiva la Técnica de Activación Muscular® (MAT®) en la resolución de la fasciosis plantar (FP) en personas corredoras habituales? Objetivo: determinar si la terapia combinada mediante ejercicios de MAT® mejora los resultados obtenidos con el procedimiento convencional en el tratamiento de la FP en personas deportistas en la ciudad de Lleida. Metodología: En este ensayo clínico experimental ha participado un total de 264 pacientes, corredores habituales con FP de más de un mes y menos de un año de evolución, que han sido derivados por sus médicos de atención primaria. La muestra se ha dividido de forma aleatoria en dos grupos, uno control que sigue un protocolo convencional (educación sanitaria, AINEs y estiramietos) y el grupo experimental, al que se le ha aplicado la intervención de MAT®. La duración del estudio es de dos años, y cada intervención dura 4 semanas con un seguimiento a 6 y 12 meses. Un analista externo es el encargado del análisis de la información mediante el programa SPSS 15.0. Los resultados se miden mediante las variables de: dolor a la presión, grosor de la aponeurosis, percepción del estado de los pies, rango de movimiento articular (RMA) de tobillo y 1era metetarsofalángica (MTF) y tiempo de vuelta a la carrera entre otras.

Neck Muscle Function and Adolescent Headache

Muscular function of the neck region may be of importance for the etiology of headache, especially of tension-type headache. However, very few data exist on the association of neck muscle function with different types of headache in adolescents. The main aim of the study was to examine the association of neck muscle function with adolescent headache. The associations between leisure time activities, endurance strength of the upper extremities (UE endurance) and mobility of the neck-shoulder region and adolescent headache were studied. In addition, the associations of force production, EMG/force ratio, co-activation and fatigue characteristics, and cross-sectional area (CSA) of neck muscles with adolescent headache were studied. The study is part of a population-based cohort study of 12-year-old children with and without headache. The study had five phases (years 1998-2003). At the age of 13 years, a sample of 183 adolescents (183/311) participated in endurance strength and mobility measurements of the neck-shoulder region. In addition, the type and level of physical and other leisure activity were elicited with open and structured questions. At the age of 17 years, a random sample of 89 adolescents (89/202) participated in force and EMG measurements of the neck-shoulder muscles. In addition, at the age of 17 years, a sample of 65 adolescents (65/89) participated in CSA measurements of the neck muscles. At the age of 13 years, intensive participation in overall sports activity was associated with migraine. Frequent computer use was associated both with migraine and tension-type headache. The type of sports or other leisure activity classified them on the basis of body loading was not associated with headache type. In girls, low UE endurance of both sides, and low cervical rotation of the dominant side, were associated with tension-type headache, and low UE endurance of non-dominant side with migraine. In boys, no associations occurred between UE endurance and mobility variables and headache types. At the age of 17 years, in girls, high EMG/force ratios between the EMG of the left agonist sternocleidomastoid muscle (SCM) and maximal neck flexion and neck rotation force to the right side as well as high co-activation of right antagonist cervical erector spinae (CES) muscles during maximal neck flexion force were associated with migraine-type headache. In girls, neck force production was not associated with headache types but low left shoulder flexion force was associated with tension-type headache. In boys, no associations were found between EMG and force variables and headache. Increased SCM muscles fatigue of both sides was associated with tension-type headache. In boys, the small CSA of the right SCM muscle and, in girls, of combined right SCM and scalenus muscles was associated with tension-type headache. Similarly, in boys, the large CSA of the right SCM muscle, of the combined right SCM and scalenus muscles, of the left semispinalis capitis muscle, of the combined left semispinalis and splenius muscles was associated with migraine. No other differences in the CSA of neck flexion or extension muscles were found. Differences in the neuromucular function of the neck-shoulder muscles were associated with adolescent headache, especially in girls. Differences in the cross-sectional area of unilateral neck muscles were associated with headache, especially in boys. Differences in the neuromuscular function and in the cross-sectional area of the neck muscles also occurred between different types of headache. It remains to be established whether the findings are primary or secondary to adolescent migraine and tension headache. Keywords: adolescent, cross-sectional area, electromyography, endurance strength, fatigue, force, headache, leisure time activity, migraine, mobility, neck muscles, tension-type headache

Calidad de vida y cáncer de próstata: un programa progresivo de fuerza-resistencia = Quality of life and prostate cancer: a progressive resistance strength program

This article presents the design and implementation of a progressive resistance strength program adapted to prostate cancer. The initial model corresponds to the guide of the American College Sports Medicine Position Stand (ACSM, 2009). This program includes the most habitual symptoms related to the illness and its treatments. The study design is quasi-experimental. The sample is 33 subjects in treatment phase. Study variables are tumour classification TNM, anthropometric measures, resistance strength, hypertension, fatigue, incontinence, pain and quality of life. After 24 weeks a significant improvement on resistance strength capacity is observed. This result is more consistent in lower extremities. Also improves hypertension, urinary incontinence, pain and quality of life. As conclusion, the improvement of the quality of life is mediated by the functional and physical capacity of the ill person

Influence on Strength and Flexibility of a Swing Phase-Specific Hamstring Eccentric Program in Sprinters' General Preparation

Guex, KJ, Lugrin, V, Borloz, S, and Millet, GP. Influence on strength and flexibility of a swing phase-specific hamstring eccentric program in sprinters' general preparation. J Strength Cond Res 30(2): 525-532, 2016-Hamstring injuries are common in sprinters and mainly occur during the terminal swing phase. Eccentric training has been shown to reduce hamstring injury rate by improving several risk factors. The aim of this study was to test the hypothesis that an additional swing phase-specific hamstring eccentric training in well-trained sprinters performed at the commencement of the winter preparation is more efficient to improve strength, ratio, optimum angle, and flexibility than a similar program without hamstring eccentric exercises. Twenty sprinters were randomly allocated to an eccentric (n = 10) or a control group (n = 10). Both groups performed their usual track and field training throughout the study period. Sprinters in the eccentric group performed an additional 6-week hamstring eccentric program, which was specific to the swing phase of the running cycle (eccentric high-load open-chain kinetic movements covering the whole hamstring length-tension relationship preformed at slow to moderate velocity). Isokinetic and flexibility measurements were performed before and after the intervention. The eccentric group increased hamstring peak torques in concentric at 60 degrees .s by 16% (p < 0.001) and at 240 degrees .s by 10% (p < 0.01), in eccentric at 30 degrees .s by 20% (p < 0.001) and at 120 degrees .s by 22% (p < 0.001), conventional and functional ratios by 12% (p < 0.001), and flexibility by 4 degrees (p < 0.01), whereas the control group increased hamstring peak torques only in eccentric at 30 degrees .s by 6% (p </= 0.05) and at 120 degrees .s by 6% (p < 0.01). It was concluded that an additional swing phase-specific hamstring eccentric training in sprinters seems to be crucial to address different risk factors for hamstring strain injuries, such as eccentric and concentric strength, hamstring-to-quadriceps ratio ratio, and flexibility.

Avaluació d’un programa de prevenció de luxacions i subluxacions d’espatlla en el judo

Aquest projecte està encarat a avaluar un protocol de prevenció de luxacions i subluxacions d’espatlla en el judo. L’objectiu principal és el de reduir el nombre de luxacions i subluxacions d’espatlla en judokes de categories compreses entre les categories cadet i absoluta millorant paràmetres com la força, la elasticitat muscular, la propiocepció, l’alimentació i la condició física dels esportistes. Aquest serà un estudi experimental amb dos grups, on el Centre de Tecnificació del Bages un realitzarà el protocol objecte d’estudi i el grup de la Federació Catalana de Judo i D.A seguiran amb la seva activitat habitual. Cada grup estarà format per 37 esportistes amb un risc alfa de 0.05 i un risc beta inferior al 0.2, amb una taxa de pèrdua de seguiment d’un 10%. Aquest protocol de prevenció pot ser útil en la nostre comunitat, però no té perquè ser-ho en altres països o regions depenent del tipus de judo que es realitza a cada lloc. Abans de començar amb l’actuació del protocol es realitzaran avaluacions biomecàniques per conèixer l’estat dels esportistes i poder actuar analíticament on més ho necessiti cada integrant de l’estudi.

Avaluació de l'efecte causat sobre els valors de potència entre un protocol d'entrenament de càrregues baixes i un amb càrregues submàximes

L’objectiu d’aquest estudi és comparar els efectes que produeixen un protocol d’entrenament orientat amb càrregues lleugeres (40%-60% 1RM) i un protocol d’entrenament amb càrregues altes submàximes (90% 1RM), sobre els nivells de potència muscular. L’estudi ha analitzat a 12 futbolistes masculins pertanyents al mateix equip (22,1 ± 2,9 anys, 72,2 ± 6, 8 kg, 1,77 ± 0,15 m). Els exercicis analitzats foren el ½ squat i el press banca. També es va utilitzar un grup control. Els resultats ens van mostrar que el grup d’entrenament amb càrregues lleugeres va obtenir unes millores més considerables sobre els valors de potència (W) en 40% i 60% 1RM i per altre banda en el grup d’entrenament amb càrregues submàximes es van produir uns increments de potència més alts en càrregues altes (80% 1RM). Els resultats referents a la velocitat mitjana (m/s), es van produir de manera més considerable en el grup que va realitzar el treball amb càrregues lleugeres, en totes les intensitats analitzades.

Protection of the high-voltage equipment with reduced insulation strength

Power transformer is the most expensive equipment on a substation. It is always necessary to get needed benefit with the lowest expenses. Producing of power transformers with reduced insulation strength is one of the possible ways to reduce expenses. Exploitation of such transformers was begun in the end of 70-th in the last century. Protection from overvoltages was done with valve-type magnetic combined surge arresters with increased blanking voltage during switching overvoltages. Nowadays there is the necessity of replacement of those devices. That’s why modernized nonlinear surge arrester was invented. This master’s thesis is focused on the use research of that modernized device in comparison with usual nonlinear surge arresters. The goal is to show the lightning overvoltages level using different types of nonlinear surge arresters and then calculations of the lightning protection reliability.

Fuerza prensil de la mano asociada al grado de autonomía y riesgo de caída en ancianos

Objetivo: Determinación de la fuerza de prensión de la mano como indicador de la capacidad funcional y grado de autonomía para actividades cotidianas en personas de la tercera edad. Diseño: Se realizó un estudio observacional de diseño transversal. Emplazamiento: Medio comunitario. Centros cívicos, centros culturales y residencias de la tercera edad de la comarca del Bages (Barcelona). 2 Participantes: Se estudió a 61 personas, 40 mujeres y 21 hombres, con un rango de edad comprendido entre los 65 y 90 años, quienes no presentaban afecciones invalidantes graves. Se solicitó su colaboración y aceptación voluntaria tras informar del objetivo del estudio. Mediciones principales: El grado de autonomía funcional se valoró mediante el test de Barthel y el test de Lawton-Brody, y el riesgo de caída mediante el test de Tinetti. La fuerza muscular máxima voluntaria (FMMV) se determinó mediante el test de prensión de la mano (handgrip). Resultados: Los hombres mostraron una correlación positiva y estadísticamente significativa (p=0.001) entre la fuerza prensil de la mano y el grado de autonomía funcional y el menor riesgo de caída (p=0.037). Dicha correlación no fue observada en las mujeres respecto al grado de autonomía (p=0.232) y fue escasa para el riesgo de caída (p=0.048). Conclusiones: El test de handgrip es una herramienta potencialmente útil para estimar la autonomía funcional e instrumental y el riesgo de caídas, especialmente en varones que sobrepasan los 65 años.

High-Performance-Tensile-Strength Alpha-Grass Reinforced Starch-Based Fully Biodegradable Composites

Though there has been a great deal of work concerning the development of natural fibers in reinforced starch-based composites, there is still more to be done. In general, cellulose fibers have lower strength than glass fibers; however, their specific strength is not far from that of fiberglass. In this work, alpha-fibers were obtained from alpha-grass through a mild cooking process. The fibers were used to reinforce a starch-based biopolymer. Composites including 5 to 35% (w/w) alpha-grass fibers in their formulation were prepared, tested, and subsequently compared with those of wood- and fiberglass-reinforced polypropylene (PP). The term “high-performance” refers to the tensile strength of the studied composites and is mainly due to a good interphase, a good dispersion of the fibers inside the matrix, and a good aspect ratio. The tensile strength of the composites showed a linear evolution for fiber contents up to 35% (w/w). The strain at break of the composites decreased with the fiber content and showed the stiffening effects of the reinforcement. The prepared composites showed high mechanical properties, even approaching those of glass fiber reinforced composites

Determination of corn stalk fibers' strength through modeling of the mechanical properties of its composites

Worldwide cultivation of corn is expanding, due in part to the increasing production of bioethanol. In consequence, huge amounts of corn stalks residues are been produced. Instead of incineration, we transformed the corn stalks into a semichemical pulp and successfully applied it as reinforcement in polypropylene composites. PP composites reinforced with 40% wt corn stalk single fibers were prepared, and their mechanical properties were evaluated. Through mechanical properties modeling of the composites, the intrinsic tensile strength of the cellulosic fibers that constitute the corn stalk have been determined