A funcionalidade e o controlo do tronco em atletas de basquetebol em cadeira de rodas e a sua relação com o desempenho motor

Projeto de Graduação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciado em Fisioterapia

Does high intensity squatting elicit post activation potentiation in the squat?

The phenomenon post activation potentiation (PAP) can be defined as an increase in muscle performance following a heavy contraction of a movement that utilizes the same muscle group (i.e. improved 20m sprint following a high intensity squat). However, research has yet to examine if heavy squats elicit PAP on the squat itself. Further, past studies have not yet analyzed if PAP is elicited at a moderate intensity (i.e. 60% one-repetition maximum-1RM).

Flujo sanguíneo cerebral durante el ejercicio de esprint

Se desconocen los efectos del entrenamiento interválico de alta intesidad (HIIT) sobre el flujo sanguíneo cerebral (FSC) y la oxigenación cerebral. Por ello reclutamos a 20 voluntarios que realizaron una sesión de HIIT (4 test de Wingate con recuperaciones de 4 minutos). Se midió la oxigenación del lóbulo frontal (OLF) y el Vastus lateralis (VL) a través de espectrofotometría cercana a los infrarrojos (NIRS). También se registró la velocidad de la sangre en las arterias cerebrales medias (vACM) mediante Doppler. La vACM disminuyó entre un 5 y 10 % en el primer esprint. En los siguientes esprints se redujo aún más. La vACM descendió en cada esprint coincidiendo con la disminución de la presión tele-espiratoria de dióxido de carbono (PETCO2) y con valores superiores de ventilación pulmonar (VE). Al interrumpirse el pedaleo se redujo bruscamente la vACM. Sin embargo, la OLF se mantuvo estable en el primer esprint sólo reduciéndose ligeramente durante el segundo y tercer Wingate (el cuarto fue similar al tercero). Este estudio muestra que la vACM disminuye durante los ejercicios de esprint, posiblemente debido a la hipocapnia. La reducción de la vACM no ejerce efectos funcionales ni relevantes sobre la oxigenación cerebral, gracias al ajuste de la conductancia vascular a través de los mecanismos de autoregulación, sin que parezca afectar negativamente al rendimiento.

Efectos de 8 semanas de entrenamiento pliométrico y entrenamiento resistido mediante trineo en el rendimiento de salto vertical y esprint en futbolistas amateurs

El presente estudio analizó los efectos de un entrenamiento pliométrico y de un entrenamiento resistido mediante arrastres de trineo de 8 semanas de duración sobre el rendimiento en pruebas de salto vertical (SJ y CMJ) y velocidad en esprint de 30 metros (tiempo parcial en 10m) en futbolistas amateurs. El estudio incluyó dos grupos experimentales que realizaron uno de los dos métodos de entrenamiento y un grupo de control. Participaron en el diseño final 26 jugadores de futbol con una media de edad de 21,38 ± 2,53 años, una altura media de 177,22 ± 6,19 cm y una media de peso corporal de 78,78 ± 12,13 kg. El programa de entrenamiento constaba de dos días de entrenamiento para los grupos de pliometría y entrenamiento resistido respectivamente, que realizaron durante 8 semanas consecutivas con una carga diferente entre las 4 primeras semanas y las 4 últimas aumentando el peso en el trineo de arrastre y la altura y distancia entre vallas. El análisis estadístico no muestra diferencias significativas entre grupos después de las 8 semanas de entrenamiento, sin embargo, en el análisis descriptivo si se aprecian cambios positivos a nivel de rendimiento tanto en salto vertical como en el esprint.

Le développement des habiletés motrices : l’influence du vécu sportif chez les étudiants en science de l’activité physique

Un nombre grandissant d’enfants en bas âge pratique un seul sport tout au long de l’année (American Academy of Pediatrics, 2000). Cette pratique, communément appelée la spécialisation hâtive, est pour plusieurs parents, entraineurs et enfants la meilleure façon d’atteindre les plus hauts niveaux de performance (rangs professionnels, compétitions internationales, bourses d’études universitaires, etc.). Toutefois, plusieurs études portant sur la performance et le développement de l’athlète proposent une alternative à la spécialisation hâtive : la spécialisation tardive (Güllich et Emrich, 2006; Lidor et Lavyan, 2002; Moesch, Elbe, Hauge et Wikman, 2011), qui est issue du modèle de la participation sportive de Côté, Baker et Abernethy (2007) et qui propose une spécialisation dans un seul sport seulement durant l’adolescence. Cette voie permettrait d’atteindre d’aussi hauts niveaux de performance, mais sans les conséquences négatives de la spécialisation hâtive. Parmi ces conséquences, Mostafavifar, Best et Myer (2013) ont émis l’hypothèse que la voie de la spécialisation hâtive mènerait à une limitation du développement des habiletés motrices. Venant ajouter à ce postulat, Fransen et ses collaborateurs (2012) ont démontré que les enfants ayant une pratique sportive diversifiée présentaient de meilleures aptitudes physiques (saut vertical et coordination). Par rapport à ces deux voies de développement, plusieurs modèles de développement (Balyi, Way et Higgs, 2013; Côté et al., 2007; Gulbin, Croser, Morley et Weissensteiner, 2013) proposent une troisième voie, la participation récréative, qui a pour finalité le maintien d’une bonne condition physique à long terme et dans laquelle le participant peut s’orienter (consciemment ou inconsciemment) dès son jeune âge ou après avoir suivi l’une des voies de la performance sportive. Devant cette diversité de voies de développement et en s’inspirant de l’hypothèse de Mostafavifar et autres (2013) selon laquelle la spécialisation hâtive mènerait à une limitation du développement des habiletés motrices et des résultats de Fransen et autres (2012) concernant les aptitudes physiques, le premier objectif est d’identifier les indicateurs du vécu sportif du participant (tels que l’âge de début du sport, le nombre de sports pratiqués, le volume d’entrainement de chacun des sports, la durée de la pratique de chacun des sports, le volume total d’entrainement et le niveau atteint dans chacun des sports) permettant d’expliquer un meilleur niveau de certaines habiletés motrices. Le deuxième objectif est de décrire la pratique sportive des étudiants et étudiantes selon les indicateurs du vécu sportif. L’hypothèse principale est qu’un participant s’inscrivant dans la voie de la performance sportive (spécialisation hâtive ou spécialisation tardive) peut diminuer ses chances de maintenir une bonne condition physique à long terme à cause d’une limitation du développement de ses habiletés motrices. Les habiletés motrices et les aptitudes physiques de 154 étudiantes et étudiants actifs en éducation physique et à la santé et en kinésiologie ont été mesurées. Le questionnaire (annexe F) a permis de quantifier certains indicateurs du vécu sportif des participants, soit (a) l’âge de début du sport, (b) le nombre de sports pratiqués, (c) le volume d’entrainement de chacun des sports, (d) la durée de la pratique de chacun des sports, (e) le volume total d’entrainement total et (f) le niveau atteint dans chacun des sports. Une analyse sommaire du questionnaire a permis d’obtenir deux autres indicateurs, soit (g) le pourcentage du volume total occupé par chacun des sports et (h) l’index des sports pratiqués (basé sur le nombre d’habiletés motrices stimulées par le sport et le nombre de sports). Le dernier indicateur, (i) les aptitudes physiques, a été calculé durant les tests physiques. Une analyse de régression multiple a été utilisée afin d’identifier parmi ces variables indépendantes le plus petit nombre d’entre elles qui explique le mieux la variabilité de la maitrise des habiletés motrices. Concernant le premier objectif, les résultats révèlent que les aptitudes physiques et l’index des sports pratiqués seraient les variables expliquant le mieux la variabilité des habiletés motrices d’un participant. Ces résultats montrent qu’il est préférable d’être génétiquement avantagé en termes d’aptitudes physiques afin d’avoir de bonnes habiletés motrices. Mais au-delà de la génétique, il demeure essentiel de solliciter les aptitudes physiques afin de les développer à leur plein potentiel (par exemple : un coureur peut avoir une excellente aptitude physique d’endurance cardiovasculaire, mais il ne pourra pas gagner de course s’il ne la sollicite pas à l’entrainement). De plus, afin de développer ses habiletés motrices, le participant devrait s’inscrire dans un parcours sportif qui lui permet de stimuler un grand nombre d’habiletés motrices, ce qui veut dire qu’au-delà du nombre de sports qu’il aura pratiqués, c’est le nombre d’habiletés motrices qu’il aura stimulées durant son vécu sportif qui lui permettra de développer ses habiletés motrices. Nos résultats viennent ainsi nuancer le postulat que la spécialisation hâtive peut mener à une limitation du développement des habiletés motrices (Mostafavifar et al., 2013) puisqu’un athlète s’étant spécialisé hâtivement dans un sport qui stimule plusieurs habiletés motrices devrait posséder un meilleur bagage d’habiletés motrices que celui ayant pratiqué plusieurs sports qui, au bout du compte, auront stimulé peu d’habiletés motrices (demi-fond, sprint, aviron, haies, bobsleigh, etc.). En ce qui a trait à l’hypothèse principale, nos résultats nous permettent d’avancer qu’un athlète s’inscrivant dans une voie de la performance sportive devrait être en mesure de maintenir une bonne condition physique à long terme si son vécu sportif a stimulé plusieurs habiletés motrices.

Assessments of training load in elite youth soccer

One of the most popular sports globally, soccer has seen a rise in the demands of the game over recent years. An increase in intensity and playing demands, coupled with growing social and economic pressures on soccer players means that optimal preparation is of paramount importance. Recent research has found the modern game, depending on positional role, to consist of approximately 60% more sprint distance in the English Premier League, which was also found to be the case for frequency and success of discrete technical actions (Bush et al., 2015). As a result, the focus on soccer training and player preparedness is becoming more prevalent in scientific research. By designing the appropriate training load, and thus periodization strategies, the aim is to achieve peak fitness in the most efficient way, whilst minimising the risk of injury and illness. Traditionally, training intensity has been based on heart rate responses, however, the emergence of tracking microtechnology such as global positioning system (GPS) and inertial sensors are now able to further quantify biomechanical load as well as physiological stress. Detailed pictures of internal and external loading indices such as these then combine to produce a more holistic view of training load experience by the player during typical drills and phases of training in soccer. The premise of this research is to gain greater understanding of the physical demands of common training methodologies in elite soccer to support optimal match performance. The coaching process may then benefit from being able to prescribe the most effective training to support these. The first experimental chapter in this thesis began by quantify gross training loads of the pre-season and in-season phases in soccer. A broader picture of the training loads inherent in these distinct phases brought more detail as to the type and extent of external loading experienced by soccer players at these times, and how the inclusion of match play influences weekly training rhythms. Training volume (total distance) was found to be high at the start compared to the end of pre-season (37 kilometres and 28 kilometres), where high cardiovascular loads were attained as part of the conditioning focus. This progressed transiently, however, to involve higher-speed, acceleration and change-of-direction stimuli at the end of pre-season compared to the start and to that in-season (1.18 kilometres, 0.70 kilometres and 0.42 kilometres high-intensity running; with 37, 25 and 23 accelerations >3m/s2 respectively) . The decrease in volume and increase in maximal anaerobic activity was evident in the training focus as friendly matches were introduced before the competitive season. The influence of match-play as being a large physical dose in the training week may then determine the change in weekly periodisation and how resulting training loads applied and tapered, if necessary. The focus of research was then directed more specifically to the most common mode of training in soccer, that also featured regularly in the pre-season period in the present study, small-sided games (SSG). The subsequent studies examined numerous manipulations of this specific form of soccer conditioning, such as player numbers as well as absolute and relative playing space available. In contrast to some previous literature, changing the number of players did not seem to influence training responses significantly, although playing format in the possession style brought about larger effects for heart rate (89.9%HRmax) and average velocity (7.6km/h-1). However, the following studies (Chapters 5, 6 and 7) revealed a greater influence of relative playing space available to players in SSG. The larger area at their disposal brought about greater aerobic responses (~90%HRmax), by allowing higher average and peak velocities (>25km/h-1), as well as greater distance acceleration behaviour at greater thresholds (>2.8m/s2). Furthermore, the data points towards space as being a large determinant in strategy of the player in small-sided games (SSG), subsequently shaping their movement behaviour and resulting physical responses. For example, higher average velocities in a possession format (8km/h-1) reflects higher work rate and heart rate load but makes achieving significant neuromuscular accelerations at a high level difficult given higher starting velocities prior to the most intense accelerations (4.2km/h-1). By altering space available and even through intentional numerical imbalances in team numbers, it may be easier for coaches to achieve the desired stimulus for the session or individual player, whether that is for aerobic and neuromuscular conditioning. Large effects were found for heart rate being higher in the underloaded team (85-90%HRmax) compared to the team with more players (80-85%HRmax) as well as for RPE (5AU versus 7AU). This was also apparent for meterage and therefore average velocity. It would also seem neuromuscular load through high acceleration and deceleration efforts were more pronounced with less numbers (given the need to press and close down opponents, and in a larger area relative to the number of players on the underloaded team. The peak accelerations and deceleration achieved was also higher when playing with less players (3-6.2m/s2 and 3-6.1m/s2) Having detailed ways in which to reach desired physical loading responses in common small training formats, Chapter 8 compared SSG to larger 9v9 formats with full-size 11v11 friendly matches. This enabled absolute and relative comparisons to be made and to understand the extent to which smaller training formats are able to replicate the required movements to be successful in competition. In relative terms, it was revealed that relative acceleration distance and Player Load were higher in smaller 4v4 games than match-play (1.1m.min-1 and 0.3m.min-1 >3m/s2; 16.9AU versus 12AU). Although the smallest format did not replicate the high-velocity demands of matches, the results confirmed their efficacy in providing significant neuromuscular load during the training week, which may then be supplemented by high-intensity interval running in order to gain exposure to more maximal speed work. In summary, the data presented provide valuable information from GPS and inertial sensor microtechnology which may then be used to understand training better to manipulate types of load according to physical conditioning objectives. For example, a library of resources to direct planning of drills of varying cardiovascular, neuromuscular and perceptual load can be created to give more confidence in session outcomes. Combining external and internal load data of common soccer training drills, and their application across different phases and training objectives may give coaches a powerful tool to plan and periodize training.

Percentiles de salto con contramovimiento en escolares de Bogotá, Colombia: Estudio FUPRECOL

Objetivo: Determinar la distribución por percentiles de salto con contramovimiento (CMJ) en una población escolar de Bogotá, Colombia, perteneciente al estudio Fuprecol. Métodos: Estudio transversal realizado entre 2846 niños y 2754 adolescentes, entre 9 a 17 años de edad, pertenecientes a 18 instituciones educativas oficiales de Bogotá, Colombia. Se evaluó el CMJ, de acuerdo, con lo establecido por la batería de condición física, Fuprecol. Se calcularon, los percentiles (P3, P10, P25, P50, P75, P90 y P97), y curvas centiles por el método LMS, según su sexo y edad. Se realizó una comparación entre los valores de la CMJ observados con estándares internacionales. Resultados: La muestra estuvo constituida por 5.600 niños y adolescentes entre 9 y 17 años; el promedio de edad fue 12,6 ± 2,4 años. En el CMJ, los valores altos, los obtuvieron los niños, franja en la que la media osciló entre 25,1 cm a los 9 años, y 38,6 cm a los 17; para las niñas, la media fluctuó entre 23,2 cm a los 9 años, y 28,6 a los 17; en ambos sexos esos valores aumentan proporcional a la edad. Conclusiones: Se registran percentiles del CMJ de acuerdo con la edad y el sexo, que podrán ser usados como referencia en la evaluación del salto vertical desde edades tempranas.

LMS tables for waist circumference and waist-to-height ratio among Colombian children and adolescents: The FUPRECOL study

Background: Indices predictive of central obesity include waist circumference (WC) and waist-to-height ratio (WHtR). The aims of this study were 1) to establish a Colombian youth smoothed centile charts and LMS tables for WC and WHtR and 2) to evaluate the utility of these parameters as predictors of overweight and obesity. Method: A cross-sectional study whose sample population comprised 7954 healthy Colombian schoolchildren [boys n=3460 and girls n=4494, mean (standard deviation) age 12.8 (2.3) years old]. Weight, height, body mass index (BMI), WC and WHtR and its percentiles were calculated. Appropriate cut-offs point of WC and WHtR for overweight and obesity, as defined by the International Obesity Task Force (IOTF) definitions, were selected using receiver operating characteristic (ROC) analysis. The discriminating power of WC and WHtR was expressed as area under the curve (AUC). Results: Reference values for WC and WHtR are presented. Mean WC increased and WHtR decreased with age for both genders. We found a moderate positive correlation between WC and BMI (r= 0.756, P < 0.01) and WHtR and BMI (r= 0.604, P < 0.01). The ROC analysis showed a high discrimination power in the identification of overweight and obesity for both measures in our sample population. Overall, WHtR was slightly a better predictor for overweight/obesity (AUC 95% CI 0.868-0.916) than the WC (AUC 95% CI 0.862-0.904). Conclusion: This paper presents the first sex- and age-specific WC and WHtR percentiles for both measures among Colombian children and adolescents aged 9–17.9 years. By providing LMS tables for Latin-American people based on Colombian reference data, we hope to provide quantitative tools for the study of obesity and its comorbidities.

Effects of dry-land strength and conditioning programs in age group swimmers

Context: Even though dry-land S&C training is a common practice in swimming, there are countless uncertainties over it effects in performance of age group swimmers. Objective: To investigate the effects of dry-land S&C programs in swimming performance of age group swimmers. Participants: A total of 21 male competitive swimmers (12.7±0.7 years) were randomly assigned to the Control Group (n=7) and experimental GR1 and GR2 (n=7 for each group). Intervention: Control group performed a 10-week training period of swim training alone, GR1 followed a 6-week dry-land S&C program based on sets/repetitions plus a 4-week swim training program alone and GR2 followed a 6-week dry-land S&C program focused on explosiveness, plus a 4-week program of swim training alone. Results: For the dry-land tests a time effect was observed between week 0 and week 6 for vertical jump (p<0.01) in both experimental groups, and for the GR2 ball throwing (p<0.01), with moderate-strong effect sizes. The time*group analyses showed that for performance in 50 m, differences were significant, with the GR2 presenting higher improvements than their counterparts (F=4.156; ƿ=0.007; η2=0.316) at week 10. Conclusions: The results suggest that 6 weeks of a complementary dry-land S&C training may lead to improvements in dry-land strength. Furthermore, a 4-week adaptation period was mandatory to achieve beneficial transfer for aquatic performance. Additional benefits may occur if coaches plan the dry-land S&C training focusing on explosiveness.

Comparison of sequence variants in the PDK4 and COX4I2 genes between racing and cutting lines of quarter horses and associations with the speed index.

Different selection objectives within the Quarter Horse breed led to the formation of groups with distinct skills, including the racing and cutting lines. With a smaller population size in Brazil, but of great economic representativeness, the racing line is characterized by animals that can reach high speeds over short distances and within a short period of time. The cutting line is destined for functional tests, exploring skills such as agility and obedience. Although the athletic performance of horses is likely to be influenced by a large number of genes, few genetic variants have so far been related to this trait and this was done exclusively in Thoroughbreds, including the g.38973231G>A singlenucleotide polymorphism in the PDK4 gene and the g.22684390C>T single-nucleotide polymorphism in the COX4I2 gene. The results of the present study demonstrate the presence of polymorphic PDK4 and COX4I2 genes in Quarter Horses. The analysis of 296 racing animals and 68 cutting animals revealed significant differences in allele and genotype frequencies between the two lines. The same was not observed when these frequencies were compared between extreme racing performance phenotypes. There were also no significant associations between alleles of the two polymorphisms and the speed index. These results suggest that the alleles of the PDK4 and COX4I2 genes, which are related to better racecourse performance in Thoroughbreds, are probably associated with beneficial adaptations in aerobic metabolism and therefore play secondary roles in sprint racing performance in Quarter Horses, which is mainly anaerobic.