[en] Several physical abilities are considered as determinant performance factors that can differentiate the level and success of a tennis player. Alongside technical proficiency, tactical awareness and certain psychological traits, some physical capacities stand out as essential for improved performance. Among these aspects, stroke velocity seems highly relevant in all age groups and in both male and female participants. The ability to apply speed to the ball, especially in the serve, seems to give the player the capacity to dominate the point and therefore a higher advantage during match-play. Previous literature has intended to establish the main physical traits that differentiate faster and slower strokes. It seems clear that these actions are of a multifactorial nature and that the outcome is the consequence of the summation of technical aspects, the anthropometric characteristics of the player, range of motion values and strength and power levels. Nevertheless, there is a certain interest in defining those physical aspects that determine velocity production in the various tennis strokes, alongside examining the possible differences between players of different ages and levels. Added, how these variables are affected by tennis competition seems essential towards training approaches and effective recovery strategies. This thesis aims at establishing those strength and power variables determinant for stroke velocity. Also, it intends to offer insights on novel measurements that may also be relevant contributors to velocity production and how these may be stimulated by new training methodologies. Last, how these determinant aspects are affected by fatigue induced by match-play will also be examined. Towards these goals, eight studies were carried out. Studies 1 and 2 correlated strength and power measurements to stroke velocity. Studies 3, 4 and 5 examined match-induced changes in the relevant variables. Study 6 approached a novel training method towards velocity enhancement and studies 7 and 8 were reviews of the literature. Results of this research show that maximal dynamic strength does not seem to positively correlate to stroke velocity in young participants. On the other hand, isometric force-time curve variables such as the rate of force development and impulse in specific joint positions of the kinetic chain seem to be relevant to perform faster strokes in these populations. This indicates the importance of a player's capacity to produce high levels of strength in short periods of time in multiple joint positions present in the motion. Because of this, training approaches that perform fast movements with light weights may be a valid option towards stroke velocity increases, although further research is needed to establish specific load prescriptions and injury risk. Also, contractile properties seem in some way relevant for velocity production, although an increased or decreased level of this variable may have a different effect on velocity production depending on the muscle group analysed. Last, single bouts of simulated match-play seem an insufficient load to elicit changes in determinant factors of stroke velocity, indicating that young players may need greater playing volumes or repetitive events to negatively affect these key variables.

[es] La velocidad de golpeo es un factor determinante del rendimiento en todos los grupos de edad y tanto en el tenis masculino como femenino. Parece claro que la capacidad de aplicar velocidad a la bola es de naturaleza multifactorial y que el resultado es la consecuencia de la suma de los aspectos técnicos, las características antropométricas, el rango de movimiento y los niveles de fuerza. No obstante, existe cierto interés por definir aquellos aspectos físicos que condicionan la velocidad en los distintos golpes, además de examinar las posibles diferencias entre jugadores de distintas edades y niveles. Conjuntamente, la forma en que estas variables se ven afectadas por la competición parece esencial para enfocar el entrenamiento y las estrategias de recuperación. Esta tesis tiene como objetivo establecer aquellas variables de fuerza y potencia determinantes para la velocidad de golpeo. Además, ofrecer información sobre nuevas variables que también pueden ser relevantes para la producción de velocidad y cómo pueden entrenarse con nuevas metodologías de entrenamiento. Por último, también se examinará cómo estos aspectos determinantes se ven afectados por la fatiga inducida por la competición. Para ello, se llevaron a cabo ocho estudios. Los resultados muestran que la fuerza dinámica máxima no parece correlacionarse positivamente con la velocidad de golpeo. Por otro lado, las variables isométricas derivadas de la curva fuerza-tiempo parecen ser relevantes para realizar golpeos más rápidos. Esto indica la importancia de la capacidad de un jugador/a de producir altos niveles de fuerza en cortos períodos de tiempo en múltiples posiciones articulares presentes en el movimiento deportivo. Además, ciertas propiedades contráctiles parecen ser relevantes para la producción de velocidad, aunque un mayor o menor nivel de esta variable puede tener un efecto positivo o negativo dependiendo del grupo muscular analizado. Por último, partidos simulados de unos 80 minutos parecen ser una carga física insuficiente para provocar cambios en los factores determinantes, lo que indica que los jugadores jóvenes pueden necesitar mayores volúmenes de juego o competiciones repetidas para afectar negativamente estas variables.