# Evaluation of Lower Extremities Power, Movement, Position and Effectiveness in Volleyball
## 1 Introduction  
Volleyball is a dynamic discipline in which a sports result will be determined by several factors related to players' physiological, anthropometric, and psychological parameters of the players, as well as the technical and tactical activities of the players [1; 2; 3]. Contemporary volleyball requires players to have a high level of speed and strength abilities, i.e., speed, jumping, jump endurance, or explosive strength. Measurements of the maximum moments of muscle strength developed by sets of muscles operating around the joints of the lower or upper extremities are often used to assess the strength, speed, and strength capacities of players in various sports disciplines. Measurements are made under isometric conditions or during isokinetic activities [4; 5]. The ability to properly indicate the parameters decisive for sports success and determine their optimal values allows us to undertake effective training activities. This issue has been discussed in many publications in recent years [2; 6; 7; 8]. Recent studies indicate the significant impact of lower limb power on the performance of volleyball players, particularly concerning their position on the court. For example, [PERSON] [9] emphasizes that playerswith higher muscle power levels perform more effective attacks and blocks, which directly translates into their success on the court. Additionally, studies on differences in muscle power across various positions [8] show that libero players have lower jumps but compensate with greater agility and reaction speed. This review of the literature demonstrates that lower limb strength plays a crucial role in shaping technical efficiency depending on the player's position. Vertical jump plays a very important role in volleyball. It is the most common motor activity performed, among others, during an attack or blockage. Each position in volleyball requires specific physical skills, which stem from the different responsibilities of players on the court. The libero, for example, focuses primarily on defense and receiving serves, which demand quick lateral movements and a low body position to effectively respond to the ball. Middle blockers must possess explosive lower limb strength, as their main tasks involve frequent jumps for blocking and first-tempo attacks. Setters, on the other hand, concentrate on precise ball distribution, and their movements are more dynamic and flexible, differing from attackers, who often perform hits from the backcourt. This differentiation of roles explains the need to study how lower limb strength affects the technical efficiency of players in various positions [10; 11]. Research shows that vertical jumps performed by volleyball players with greater effectiveness of the game are performed at a higher level of effectiveness compared with less successful players and that they are the basic indicator that allows the assessment of the fitness of a volleyball player [12]. The topic of effectiveness in volleyball has been discussed in many publications. They focused on the importance of the performance of technical activities in relation to statistics and positions on the field, as well as differences between the levels of competition and gender [8; 13; 14; 15; 16; 17]. There are five positions in volleyball: opposite hitter, middle blocker, outside hitter, setter, and libero. Actions taken by players in certain positions very often depend on many different factors [17; 18]. Each position has a different role played by the players on the court. The task of the opposite hitter is to receive the ball after the opponent's serve, defensive play combined with attacks on the wings or from the backcourt (attack from the sixth zone). The main task of the middle blocker is to block the attacks and attack at the first rate (attack from the third zone). The attacker has to finish the action with an attack after the setter has passed the ball. They also take part in the team's defense play (block, defense). The setter's task is to pass the ball to the players participating in the attack.