Neuro-mechanical and metabolic adjustments to the repeated anaerobic sprint test in professional football players.

PURPOSE: This study aimed to determine the neuro-mechanical and metabolic adjustments in the lower limbs induced by the running anaerobic sprint test (the so-called RAST). METHODS: Eight professional football players performed 6 × 35 m sprints interspersed with 10 s of active recovery on artificial turf with their football shoes. Sprinting mechanics (plantar pressure insoles), root mean square activity of the vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) muscles (surface electromyography, EMG) and VL muscle oxygenation (near-infrared spectroscopy) were monitored continuously. RESULTS: Sprint time, contact time and total stride duration increased from the first to the last repetition (+17.4, +20.0 and +16.6 %; all P < 0.05), while flight time and stride length remained constant. Stride frequency (-13.9 %; P < 0.001) and vertical stiffness decreased (-27.2 %; P < 0.001) across trials. Root mean square EMG activities of RF and BF (-18.7 and -18.1 %; P < 0.01 and 0.001, respectively), but not VL (-1.2 %; P > 0.05), decreased over sprint repetitions and were correlated with the increase in running time (r = -0.82 and -0.90; both P < 0.05). Together with a better maintenance of RF and BF muscles activation levels over sprint repetitions, players with a better repeated-sprint performance (lower cumulated times) also displayed faster muscle de- (during sprints) and re-oxygenation (during recovery) rates (r = -0.74 and -0.84; P < 0.05 and 0.01, respectively). CONCLUSION: The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour. Our results also strengthen the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates.

The real estate markets : Players, institutions and territories

Revealing the parties, the processes and the institutions and, consequently, both the diversity and contingency of the real estate markets, the existing increasing literature emphasises the contemporary numerous links and interdependencies between real estate, land value, planning and town planning policy and even the financial system. This paper is an attempt to understand all the real estate markets, from the most peripheral ones, where the urban rent is the lowest, to the most dense city centres. To gain a better understanding of the real estate market, a process of firstly deconstruction and then reconstruction is used. The process of deconstruction involves identifying various market trends according to property type (principally residential buildings), players and institutions, territorial situations and temporalities based on research conducted in Switzerland. We then developed a meta-synthesis inspired by Fernand Braudel whose works put as much emphasis on day-to-day economic activity as on long-term activity, and on local as well as global issues.

Study of the effect of oral health on physical condition of professional soccer players of the Football Club Barcelona

Objectives: The objective of this study was to evaluate the oral health status of professional soccer players of F.C. Barcelona and its relation to the incidence of sport lesions. Methods: Thirty professional soccer players were consecutively evaluated in the seasons 2003/4, 2004/5 and 2005/6. A research protocol to assess their oral health was developed. DMFT, Quigley & Hein plaque index (PI), Löe & Silness gingival index (GI), World Health Organization malocclusion index, Ramfjord teeth probing pocket depth (PPD), TMJ examination and history of dental trauma were recorded. All physical injuries sustained by players during the season were documented from F.C. Barcelona medical services. Results: Mean DMFT score was 5.7 (SD 4.1), Quigley & Hein plaque index score was 2.3 (SD 1.1), Löe & Silness gingival index was 1.1 (SD 0.8), and periodontal pocket depth was 1.9 mm (SD 0.3). Pearson"s analysis showed a significant correlation between PI and GI (p<0.01). Nine players (30%) presented bruxism - the same proportion of those with severe malocclusion. Seven (23.3%) players had suffered uncomplicated crown fractures. The mean incidence of physical injuries was 8 (SD 3.4) per player. PI and PPD showed a statistically significant correlation to muscle injuries (p<0.05). Conclusions: Soccer players, despite intensive medical follow-up, have significant oral health problems such as untreated caries, gingivitis or malocclusion, and suffer dental trauma as a result of sports activities. Their physical condition could also be associated to oral health

Dynamic Criteria: a Longitudinal Analysis of Professional Basketball Players" Outcomes

This paper describes the fluctuations of temporal criteria dynamics in the context of professional sport. Specifically, we try to verify the underlying deterministic patterns in the outcomes of professional basketball players. We use a longitudinal approach based on the analysis of the outcomes of 94 basketball players over ten years, covering practically players" entire career development. Time series were analyzed with techniques derived from nonlinear dynamical systems theory. These techniques analyze the underlying patterns in outcomes without previous shape assumptions (linear or nonlinear). These techniques are capable of detecting an intermediate situation between randomness and determinism, called chaos. So they are very useful for the study of dynamic criteria in organizations. We have found most players (88.30%) have a deterministic pattern in their outcomes, and most cases are chaotic (81.92%). Players with chaotic patterns have higher outcomes than players with linear patterns. Moreover, players with power forward and center positions achieve better results than other players. The high number of chaotic patterns found suggests caution when appraising individual outcomes, when coaches try to find the appropriate combination of players to design a competitive team, and other personnel decisions. Management efforts must be made to assume this uncertainty.

The Effect of Two Speed Endurance Training Regimes on Performance of Soccer Players.

In order to better understand the specificity of training adaptations, we compared the effects of two different anaerobic training regimes on various types of soccer-related exercise performances. During the last 3 weeks of the competitive season, thirteen young male professional soccer players (age 18.5±1 yr, height 179.5±6.5 cm, body mass 74.3±6.5 kg) reduced the training volume by ~20% and replaced their habitual fitness conditioning work with either speed endurance production (SEP; n = 6) or speed endurance maintenance (SEM; n = 7) training, three times per wk. SEP training consisted of 6-8 reps of 20-s all-out running bouts followed by 2 min of passive recovery, whereas SEM training was characterized by 6-8 x 20-s all-out efforts interspersed with 40 s of passive recovery. SEP training reduced (p<0.01) the total time in a repeated sprint ability test (RSAt) by 2.5%. SEM training improved the 200-m sprint performance (from 26.59±0.70 to 26.02±0.62 s, p<0.01) and had a likely beneficial impact on the percentage decrement score of the RSA test (from 4.07±1.28 to 3.55±1.01%) but induced a very likely impairment in RSAt (from 83.81±2.37 to 84.65±2.27 s). The distance covered in the Yo-Yo Intermittent Recovery test level 2 was 10.1% (p<0.001) and 3.8% (p<0.05) higher after SEP and SEM training, respectively, with possibly greater improvements following SEP compared to SEM. No differences were observed in the 20- and 40-m sprint performances. In conclusion, these two training strategies target different determinants of soccer-related physical performance. SEP improved repeated sprint and high-intensity intermittent exercise performance, whereas SEM increased muscles' ability to maximize fatigue tolerance and maintain speed development during both repeated all-out and continuous short-duration maximal exercises. These results provide new insight into the precise nature of a stimulus necessary to improve specific types of athletic performance in trained young soccer players.

Russian mobile telecommunications market: players and trends

Objective of this work was to clarify the competitive situation of Russian mobile telecommunications market: who are the main players, are there many regional operators, what is the possibility of new entrants and how intensive is the competition. In the beginning the history of Russian mobile telecommunications sector is described. In the next chapter environmental factors of the market are examined with the help of PESTEL analysis. After that, players of the market are introduced to ease the following of next chapters. The main theory for this work was industry analysis of five competitive forces by Michael Porter, which is presented before the theory related industry analysis of Russian mobile telecommunications industry. Research for the industry analysis is mainly based on up-to-date articles describing Russian market. As a result of the industry analysis, competitive situation of Russian mobile telecommunications industry and the future prospects are described with the help of factors coming from the PESTEL-analysis. Finally development and future prospects for Russian 3G are reported. As a result of this work, it can be said that Russian mobile telecommunications market is not likely to maintain the growth of previous years, because the market is near saturation. According to passive SIM-cards it has already received saturated. The saturation will also make the market share game between operators more volatile. The market is dominated by three national operators that covered 88% of the income in the first half of 2007. In addition to these three, there are also several regional operators. Structure of the market is likely to consolidate.

L'impacte d'un programa de tennis com a eina de millora de la qualitat de vida i l'estrès percebut en dones físicament inactives d'entre 43 i 50 anys

Introducció: L’activitat física és una necessitat imprescindible per a la salut de les persones, i tot i ser conscients dels seus beneficis encara es troben alts percentatges d’inactivitat física i sedentarisme. Per aquest motiu, els objectius principals d’aquest estudi són esbrinar si les dones adultes d’entre 43 i 50 anys que realitzen activitat física regularment, més concretament que practiquen l’esport del tennis, tenen una qualitat de vida i un estrès percebut millor que les que no realitzen activitat física, i per tant, valorar l’impacte d’un programa de tennis adequat i específic, és a dir, adaptat a les característiques i les necessitats dels alumnes, com a eina per millorar aquestes dues variables: l’estrès percebut i la qualitat de vida. Metodologia: El treball és un estudi experimental el qual consta d’una mostra total de 12 dones, 6 es varen assignar al grup control (practiquen el tennis) i 6 al grup intervenció (no realitzen AF), i totes elles de manera aleatòria. Les participants del grup intervenció varen realitzar un programa de 8 sessions de 60 minuts de treball durant 4 setmanes, mentre que les participants del grup control van seguir la seva rutina habitual. Les variables dependents (qualitat de vida i estrès percebut) es varen mesurar abans i després de la intervenció. Resultats: Els resultats obtinguts mostren, pel que fa al grup intervenció, millores significatives respecte a les dues variables mentre que el grup control presenta alguna mínima millora puntual però, en general no es produeixen canvis. Quan a la variable de qualitat de vida, les participants del grup intervenció han obtingut millores en les 8 dimensions del qüestionari un cop finalitzat el programa, les quals han estat més significatives pel que fa al rol emocional i la funció física. I respecte a l’estrès percebut, el grup intervenció ha aconsegui reduir el seu nivell d’estrès 3’17 punts. Discussió: Per tant, podem dir que el tennis, amb el disseny adequat d’un programa, millora l’estat de salut de les persones, en aquest cas redueix l’estrès percebut i millora la qualitat de vida. Extretes les conclusions i coneixent l’elevat nombre de dones que practiquen el tennis és de gran interès i molt factible oferir aquest programa a clubs de tennis amb l’objectiu de millorar la salut de les persones.

Influències del tipus de superfície en el rendiment dels jocs al servei i a la restada en jugadors ATP (2013)

L’objectiu d’aquest estudi és descobrir com influeix la superfície de la pista de tenis en el rendiment dels jugadors a l’hora d’aconseguir un major percentatge de jocs guanyats, factor determinant en el resultat final. Per controlar aquest factor diferenciarem entre els disputats en servei i en restada, per tenir així una visió més acurada del tenis d’elit. La mostra escollida està composta per els 50 tenistes millor classificats a final de l’any 2013. S’incorporarà també la variable de l’alçada del jugador per veure si aquesta es també un factor influent. Es conclou l’estudi sabent que la superfície d’herba ajuda a un major èxit en els jocs al servei, més que en les superfícies dures i la terra batuda. Pel que fa a la restada, trobem que en la superfície d’herba, la mostra dels jugadors analitzats guanya un percentatge menor que sobre pista ràpida i terra batuda. Tot i això, les diferències no semblen gaire grans entre unes i altres. Per determinar si els jugadors actuals estan adaptats a aquestes 3 superfícies per igual es va agafar el percentatge de jocs guanyats en la millor i la pitjor superfície (descartant l’intermèdia), i s’establí una mitjana entre els 50 tenistes. Els resultats indicaren que la majoria de jugadors segueixen notant el canvi de superfície, tot i això, la majoria d’ells estan capacitats per guanyar partits en les altres pistes. Obtinguérem també una alta correlació entre l’alçada del tenista i una major diferència entre el percentatge de jocs guanyats en el servei en comparació amb la restada.

A comparison of injuries among children and adult football (soccer) players

Football is a universal and an affordable game but we need to minimize the incidence of accidents among the increasing number of young football players. Our 11 year retrospective epidemiological study (1990-2000) of football injuries in children (N= 1000) was compared with those of adult players in the 2006 European Championship. This comparative study confirmed that the anatomical, biomechanical and biological conditions differ between adults and children and that they warrant particular attention to protect the latter vulnerable group against bone avulsions, overuse pathologies and fatigue-fractures. Injuries were shown to increase significantly with age up to 16 years (P=0.005). Children suffer mainly from contusions, fractures and sprain injuries. Head injuries were more common in boys (P=0.070), while girls were more prone to sprains. The types of injuries differ between adults and children (sprain versus fractures), the anatomical location of injuries is different (lower limbs in adults, lower and upper limbs in children), the circumstances of the injuries are different (contact in adults versus non-contact in children), and teenage girls have different types of injuries than teenage boys. An increased incidence of injuries is due to changes in the position of the center of gravity and in the morphotype during rapid growth. For these reasons it is mandatory to adapt the training to the age and sex of the players. It is unsafe to train children the same way as adults. The height, the weight and the speed of growth must be taken into account by the multidisciplinary team when organising the training programmes. -- Le football fait partie des sports les plus pratiqués au monde en raison de sa popularité et de son accessibilité économ ique. L'incidence des blessures liées à cette pratique doit être diminuée surtout chez les jeunes joueurs en raison de la croissance exponentielle du nombre de joueurs féminins et masculins. Une étude épidémiologique rétrospective sur 11 ans (1990-2000) a été réalisée chez les enfants victimes de blessures liées au football (N==1000), puis a été comparée aux données recueillies de l'UEFA lors d'un Championnat Européen en 2006 sur les lésions des joueurs adultes. Cette étude comparative confirme que les structures anatomiques, biologiques et les tensions biomécaniques chez l'enfant diffèrent de celles de l'adulte. Les enfants ont un risque plus élevé de souffrir d'avulsion osseuse et de fractures de fatigue que les adultes. Les blessures augmentent significativement avec l'âge jusqu'à 16 ans (P==0,005). Les traumatismes crâniens sont plus fréquents chez les garçons tandis que les entorses sont plus à risque chez les filles. Les adultes font plus souvent des entorses tandis que les enfants font plus de fractures. La localisation anatomique diffère également entre ces deux groupes (les membres inférieurs chez l'adulte et les membres inférieurs et supérieurs chez l'enfant). La circonstance des blessures diffère également (choc avec un autre joueur chez l'adulte et des blessures sans contact chez l'enfant). Chez les adolescents, les blessures des filles diffèrent de celles des garçons. L'augmentation chez les enfants de cette incidence est liée au déplacement lors de la croissance du centre de gravité, avec une maladresse accrue lors des phases de croissance. Pour toutes ces raisons, il est justifié d'adapter les entraînements de football en fonction de l'âge, du sexe et du morphotype. L'entrainement des enfants doit être différent de celui des adultes. Le poids, la taille et la vitesse de croissance doit être prise en compte dans des structures multidisciplinaires afin de permettre une meilleure longévité sportive des jeunes joueurs de football.