From “sliding” to “winding” filaments theory: A narrative review of mechanisms behind skeletal muscle contraction

The physiological mechanisms behind muscle contraction are a main concept in sport medicine and rehabilitation. The sarcomere is the functional unit of skeletal muscle and several proteins definite its complex structure. The most common theory to explain muscle contraction was proposed in the last 50’s and has become widely popular and accepted: the “sliding filaments” theory. Even if this hypothesis was able to justify some form of muscle contraction, other processes are not fully described by it. Eccentric contraction and some phenomena, like the “force enhancement during stretch” concept described in the 2002, are not explicable according to the sliding filament theory. Therefore, several hypotheses have been suggested over the years, such as the “popping sarcomeres” theory and the “winding filament” theory. Some other proteins, like titin, have gained a main role in the physiology of the sarcomere and should be relevant to explain mechanisms of eccentric contraction, where the sarcomere generates highest level of tension while it is lengthening. The aim of this review is to summarize the physiological theories of muscle contraction and to define concepts applicable in sport medicine and in rehabilitation areas

Pilates Improvement the Individual Basics of Service and Smash in Volleyball

A sample of 20 players 12-to 14-year old young male volleyball athletes participated in this study to test the improvement of agonistic performance, especially for the individual basics of the service and smash, using Pilates method in additional training sessions. The research was conducted with observation and manual and computerized detection for six months with tests for explosive strength detection and smash precision. The measuring the length of the lower limbs with the ASIS method showed a diff erence of a few millimetres between the two lower limbs and hypertrophy of the longest limb and hypotrophy of the shortest one. The athletes were divided into group A control (10 athletes) and group B (10 athletes). Only Group B participated in 20 additional training sessions with the Pilates method. The study showed improvement in performances with particular reference to the average percentage of crushing between 4 and 7%. Group B athletes, they found a uniform muscle toning and improved breathing control. The A group, motivated to perform the workouts with greater concentration, showed a performance improvement of a few percentage points. These athletes can improve the eff ectiveness of using unconventional methods to improve sports performance in a Team Sport

Wear Behavior of AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion and Gravity Casting

Herein, the sliding wear behavior of AlSi10Mg samples realized using laser‐based powder bed fusion (LPBF) is investigated via pin‐on‐disc (PoD) tests, before and after T6 heat treatment. The changes in the microstructure, density, and hardness induced by heat treatment are correlated with the tribological behavior of the alloy. Furthermore, short wear tests are conducted and the resulting wear tracks are investigated through scanning electron microscopy (SEM), equipped with an energy‐dispersive spectroscopy (EDS) microprobe to elucidate how the wear mechanisms evolve with sliding distance. For comparison, gravity cast (GC) AlSi10Mg samples are also characterized and tested. The as‐built additive manufacturing (AM) sample exhibits the lowest wear rate and coefficient of friction because of its high hardness and relative density, whereas the heat‐treated sample shows the worst behavior in comparison with the GC samples. The results suggest a significant influence of porosity on the wear behavior of AM alloys

Biodiversity of vegetable crops, a living heritage

Biodiversity is the natural heritage of the planet and is one of the key factors of sustainable development, due to its importance not only for the environmental aspects of sustainability but also for the social and economic ones. The purpose of this Special Issue is to publish high-quality research papers addressing recent progress and perspectives while focusing on different aspects related to the biodiversity of vegetable crops. Original, high-quality contributions that have not yet been published, or that are not currently under review by other journals, have been gathered. A broad range of aspects such as genetic, crop production, environments, customs and traditions were covered. All contributions are of significant relevance and could stimulate further research in this area

Cavitation erosion resistance of 1.2709 alloy produced via Laser-Powder Bed Fusion

Maraging steels, like 1.2709 (18Ni-300), are attractive materials for the aerospace, automotive, tooling, and bearing gear industries because of their high yield, tensile strength, and good toughness. The low-carbon martensite matrix and nanoscale intermetallic precipitates combine to provide distinctive mechanical properties. In particular, due to their low carbon content, these steels are easily weldable and are therefore appropriate for additive manufacturing (AM) processes like laser-based powder bed fusion (LPBF). The tooling and molding industry has just lately started using this fabrication technique to create inserts with conformal cooling channels that can extend the lifetime of the insert and core while boosting the cast quality. These parts are frequently exposed to high levels of stress, wear, and even aggressive conditions. In this context, this research focuses on a peculiar, and thus understudied, erosion phenomenon known as cavitation erosion. According to the ASTM G32 standard, the cavitation erosion resistance of 1.2709 maraging steel samples produced by additive manufacturing as well as by forging was investigated. Microstructural analyses were carried out to evaluate the effect of the different microstructures resulting from the different manufacturing techniques on erosion behavior. When compared to the forged maraging steel, the AM one shows less resistance to the initiation of the erosion phenomenon. Nevertheless, the wear rates of the two materials are comparable

Analisi di una proposta inclusiva per soggetti BES attraverso la pratica sportiva di squadra

The inclusion is a phenomenon that involves contemporary society. The school inclusion, in particular, is confronted with the educational emergencies that require appropriate teaching responses that must be developed in suitable learning environments. The purpose of the research was to promote inclusive relationships between SEN subjects and all the other students, so that the school can promote the right that a person is considered equal to others but different at the same time along with the other, through an act motor nature trail to favor group collaborative activities with the game of basketball.L’inclusione è un fenomeno che investe la società contemporanea. L’inclusione scolastica, in particolare, si deve confrontare con le emergenze educative che necessitano di adeguate risposte didattiche che devono essere sviluppate in idonei ambienti di apprendimento. Lo scopo della ricerca è stato quello di favorire le relazioni inclusive tra i soggetti BES e tutti gli altri allievi, affinchè la scuola possa promuovere il diritto che un soggetto venga considerato uguale agli altrima allo stesso tempo diverso insieme agli altri, attraverso un percorso didattico motorio atto a favorire le attività collaborative di gruppo con il gioco della pallacanestro

Physical-technical conditions, coaching and nutrition: An integrated approach to promote cohesion in sports team

The aim was verified that the level of cohesion of a sports group is conditioned by numerous variables, which affect the athletes performance and lead to difficulties in adults relationships. The sample physical-technical and nutritional conditions and the help for the cohesion of a technique such as coaching were evaluated. Coaching can understand as the process in which individuals, mostly athletes, supported for their improvement and development in order to achieve performance high levels. 40 adults, aged between 35 and 45 years old, practicing football at amateur level for eight months, belonging to two different sports groups (blue and red group), have been observed. The results showed about 2.5% increase for blue group in Cooper test and about 1% in Sargent test, while for red group the improvement was approximately 1.5% in Cooper test and about 0.5% in Sargent test. 37 athletes correctly followed the nutrition specialists indications while 3 athletes showed negative responses. The personalized diets success confirmed by the decrease, in terms of kg, of the average percentage of athletes' body weight. All sample highlighted, with the answers to the 14 items of the questionnaire, significant percentage variations in lifestyles and relationships between group members

Valorizzazione del corpo nella proposta didattica al soggetto con Sindrome dello Spettro Autistico

The theoretical and diagnostic approaches to Autistic Syndrome havechanged over the years following the results of clinical studies that have establishedthe organic etiology as well as behavioral. It is still difficult toidentify with certainty the cause of the disease but are more clear types oftreatments to use. At scholastic level, the number of autistic children attendingpublic schools has increased and intervention teaching techniqueswere perfected. Of particular importance is the enhancement of the bodythat silent body must become a living body capable of action and conveyemotions limiting redundancies, stereos and establishing effective relationships.Gli approcci teorici e diagnostici relativi alla Sindrome Autistica sono mutatinel corso degli anni in seguito ai risultati delle ricerche cliniche che hannosancito l’etiologia organica oltre che comportamentale. Risulta ancora difficileindividuare con certezza la causa della patologia ma sono più chiari letipologie di trattamenti da utilizzare. A livello scolastico il numero deisoggetti autistici frequentanti le scuole pubbliche è aumentato e sono stateperfezionate le tecniche didattiche d’intervento. Particolare importanzariveste la valorizzazione del corpo che da corpo muto deve diventare uncorpo vivo capace di agire e trasmettere emozioni limitando le ridondanze,le stereotipie e stabilendo efficaci relazioni

Supplementary Far-Red Light Did Not Affect Tomato Plant Growth or Yield under Mediterranean Greenhouse Conditions

In the Mediterranean region, tomato plants are often cultivated in two short cycles per year to avoid the heat of summer and the low solar radiation of winter. Supplementary light (SL) makes it possible to cultivate during the dark season. In this experiment, a tomato F1 hybrid cultivar DRW7723 was cultivated in a greenhouse for a fall-winter cycle. After transplant, light emitting diode (LED) interlighting, with two light spectra (red + blue vs. red + blue + far-red) was applied as SL. Plant growth, yield, gas exchange, nutrient solution (NS) consumption, and fruit quality were analyzed. In general, the eects of adding far-red radiation were not visible on the parameters analyzed, although the yield was 27% higher in plants grown with SL than those grown without. Tomatoes had the same average fresh weight between SL treatments, but the plants grown with SL produced 16% more fruits than control. Fruit quality, gas exchange and NS uptake were not influenced by the addition of far-red light. Interlighting is, therefore, a valid technique to increase fruit production in winter but at our latitude the eects of adding far-red radiation are mitigated by available sunlight

Use and attitudes toward dietary supplements and drugs amongst Italian elite athletes and its correlation with banned doping substances

Athletes frequently use dietary supplements (DS) to find better results as soon as possible. Moreover, they also will be occurring in “polypharmacy” or in substances prohibited for doping. The aim of this retrospective sectional study was to explore use and attitudes toward drugs and dietary supplements (DS) in Italian Sports Federations and its correlation with banned doping substances token amongst elite athletes. The data shows the results from 2012 to 2017, among Italian Sports Federations elite athletes and the analysis of the anti-doping controls from the Ministry of Health annual reports. The results show that the largest number of supplements consumption declarations was recorded in 2014 in sport as cycling and athletics. Moreover, in the same year and in 2012 there were 48 and 42 declarations on 58 and 52 doped athletes. Among the Italian federations, three are particularly controlled: FCI - cycling, FIDAL - athletics and FIGC – football. Most of the consumers subjects are male athletes. So maybe there is a link between NS and positive results in anti-doping test. The consumption of health products is constantly expanding and educational interventions will be needed to improve drugs and DS use about elite athletes as well in amateur athletes