PNF Effects on Volleyball Performance

The successes achieved by both our club volleyball teams and the national volleyball team in our country have led to an increase in interest among young people in the sport of volleyball and their desire to become volleyball players. Volleyball is a team sport that involves strategies such as jumping, blocking spikes, executing short and explosive movements, and rapidly adjusting one's position to set the ball over the net. The primary objective of the game is to score points while preventing the opposing team from doing the same. Fundamental techniques in volleyball include the serve and the spike. A spike is a move that concludes a rally and secures a point, whereas a serve is the technical action that initiates every point (Baena-Raya, 2021).There are three main styles of serving in volleyball-the jump serve, the jump-float serve, and the standing (non-jump) serve-which differ based on the rotation imparted to the ball and the execution method (Pawlik, 2024; Cavedon, 2024; Altundag, 2024). Research indicates that female athletes tend to prefer the jump-float serve, while the jump serve is associated with a higher risk of shoulder injury (Reeser, 2010). The spiking technique used in volleyball is categorized into two forms: the traditional technique (TT) and the alternative technique (AT). In the traditional technique, the shoulder reaches full flexion, whereas in the alternative technique, the arm follows a whip-like motion and stops at an angle of approximately 90° (Seminati, 2015). The key parameters that determine the speed of a spike include technical and kinematic variables (Cavedon, 2023), such as explosive power, the capacity and quality of the vertical jump, the force-velocity balance (Pleša, 2021; Baena-Raya, 2021), upper extremity strength (Forthomme, 2005), and anthropometric characteristics and body composition (Challoumas, 2018). During the execution of a spike, the athlete-typically while airborne and lacking support from the lower extremities-strikes the ball using their upper arm and torso (Shih, 2019). Two significant factors that determine the speed at which the ball is struck are core stability and scapular stabilization. Core stability ensures spinal stability and motor control by maintaining an appropriate balance of loads across the spine, pelvis, and the kinetic chain. It has been observed that individuals with lower core stability also exhibit lower spike speeds (Alsarraf, 2015). The coordinated action of the scapular stabilizers facilitates efficient movement at the glenohumeral (shoulder) joint and supports the optimal function of the shoulder complex (Paine, 2013). In volleyball, actions such as spiking, serving, and blocking require the frequent, high-speed use of the upper extremities, often involving upward movements. Throughout these actions, the scapula-shoulder-arm complex plays a critical role. If scapular stabilization is insufficient or movement coordination is impaired, even when the arm's point of contact is high, the resulting loss in effective force transmission can lead to decreased performance, increased load on the shoulder joint, and a higher risk of injury (Kibler, 2013). Volleyball players face an increased risk of overuse injuries due to the repetitive execution of the spike during both training sessions and matches (Howard, 2023). When performing a spike, players must generate the force required to strike the ball using the muscles of the shoulder girdle and the trunk (Shih, 2019). Poor core stability can elevate injury risk-particularly in female athletes-by contributing to postural deviations such as excessive spinal extension, reduced posterior tilt of the scapula, and increased glenohumeral elevation (Kuniki, 2022). Furthermore, it has been noted that repetitive overhead movements can compromise the dynamic stability of the scapula, potentially leading to injuries in the shoulder girdle (Pascoal, 2023). Improving scapular muscle control may help reduce the risk of shoulder injuries (Pascoal, 2023). Strengthening the muscles of the shoulder girdle and/or the trunk can both prevent injuries associated with the spiking motion and enhance an athlete's performance (Challoumas, 2017). The coordinated function of the abdominal, gluteal, pelvic girdle, and paraspinal muscles is critical for improving athletic performance and preventing injuries. In clinical practice, "lumbar stabilization exercises" are employed as a therapeutic approach for both performance enhancement and the treatment of lower back pain (Akuthota, 2008). Proprioceptive Neuromuscular Facilitation (PNF) techniques are a therapeutic method involving specific movement patterns and technical applications designed to improve muscle strength and neuromuscular coordination (Sayaca, 2020). Fundamentally, PNF is a treatment concept that aims to unlock the full potential of every individual, including those with disabilities (Kabat, 1950). The term "proprioceptive" relates to sensory receptors that provide information about body movement and position. PNF is an integrated approach; treatment is directed toward the individual as a whole, rather than focusing solely on a specific problem or body part. The therapist consistently focuses on revealing the patient's physical and psychological potential, maintaining a positive therapeutic approach throughout. By integrating principles of motor control and motor learning, this approach strives to help the individual reach their highest level of functioning. Consequently, PNF is a treatment approach that supports functionality at the levels of body structures, activity, and participation, aligning with the World Health Organization's International Classification of Functioning, Disability and Health (ICF, 1997) framework (Kaya Utlu, 2023). In the existing literature, factors influencing scapular and core stabilization in volleyball players have been examined. However, no study has been found that investigates the effects of PNF techniques-applied to the upper extremities and the core region-on spike velocity, core and scapular stabilization, and upper extremity performance in adolescent volleyball athletes. The aim of this study is to examine the effects of PNF techniques applied to the upper extremities and the core region on spike velocity, core and scapular stabilization, and upper extremity performance in adolescent volleyball players. The athletes included in the study will be divided into three groups (Control, Trunk, and Upper Extremity) using a simple randomization method. Prior to the study, all athletes in each group will be assessed by the same individual, following a standardized sequence. Athletes in the Trunk and Upper Extremity groups-who will participate in a PNF exercise program (3 sessions per week for 6 weeks, totaling 18 sessions)-as well as those in the control group-who will not undergo any PNF exercise program-will be re-assessed by the same individual after 6 weeks.

Assessment Methods:

Plank Test: The "Plank Test" will be used to assess the strength and stability of the athlete's core region. The athlete will be positioned face-down on a flat surface, with the back, neck, and head aligned in the same plane; feet spaced hip-width apart; ankles and elbows flexed at 90°; and the knees and hips lifted off the ground, creating a straight line from head to feet. Once the athlete assumes this position, the evaluator will start a stopwatch, which will be stopped the moment the athlete's form breaks (McKenzie, 2005). The test will be repeated three times, with a 1-minute rest interval between each attempt. The highest recorded value will be used for analysis. The validity and reliability (95% CI, 0.94-0.99) of the test were established by Tong, Wu, and Nie (2014).

Seated Medicine Ball Throw Test: The "Seated Medicine Ball Throw Test" will be used to measure the explosive power of the bilateral upper extremities. The athlete will sit on the floor with their legs extended straight, while their shoulders, back, and head remain in contact with a wall. The athlete will position their arms with the elbows bent and shoulders abducted to 90°, holding a medicine ball against their chest, with their palms facing each other. From this position, the athlete will be instructed to bend their knees and then throw the ball as far forward as possible. The distance will be measured using a tape measure, taking the point where the ball first touches the ground as the reference. The test will be repeated three times, with a 30-second rest interval between each throw. The highest value recorded will be used for analysis (Hermassi, 2010).

Upper Extremity Y-Balance Test: The "Upper Extremity Y-Balance Test" will be used to assess the dynamic stability capacity of the upper extremity being tested. A tape measure (or measuring scale) will be positioned on the floor such that the angle between the inferolateral (downward and outward) and superolateral (upward and outward) reach directions is 90°, and the angle between these directions and the medial (inward) reach direction is 135°. The athlete will be positioned on the floor with their feet no more than 12 inches (30.48 cm) apart, their elbows extended, and their hands placed at the central intersection point of the measuring scales. While maintaining this position, the athlete will be instructed to reach as far as possible with the non-tested upper extremity in the medial, inferolateral, and superolateral directions; the furthest point reached will be marked and recorded on the measuring scale. Athletes will repeat the test three times, and the greatest reach distance achieved will be taken as the reference value (Gorman, 2012; Westrick, 2012). Upper extremity length will be determined by measuring the distance from the spinous process of the C7 cervical vertebra to the tip of the middle finger on the non-dominant side (Salo \& Chaconas, 2017). The results obtained will be calculated using the formula "(medial + inferolateral + superolateral reach distance) / (3 × arm length) × 100" and used in the analysis (Gorman, 2012; Westrick, 2012).

Spike velocity: The spike velocity of athletes during a serve/spike action will be measured using the Bushnell Velocity Radar Gun. The athlete will be asked to assume a spiking position, while the evaluator will stand directly opposite them. The athlete will be instructed to perform a spike at the highest possible speed. A total of three measurements will be taken, and the highest recorded speed will be used for analysis. Athletes will not be provided with a rest period and will be asked to perform the spike as soon as they are ready (Kuyulu Haksal, 2024).

Scapular Dyskinesis Tests: "Scapular Dyskinesis Tests" will be used to determine the presence of any scapular movement dysfunction within the shoulder girdle. Assessment will involve both static and dynamic scapular movements. Static scapular assessment includes the Lateral Scapular Slide Test (LSST), which is performed while the participant is in a standing position. Measurements are taken at three different shoulder positions (neutral, 45° abduction, and 90° abduction) across two specific points: 1) the distance between the T3 vertebra and the medial border of the scapula, and 2) the distance between the T7 vertebra and the inferior angle of the scapula. These measurements will be taken using a tape measure, and the difference between the two sides will be calculated. A difference greater than 1.5 cm between the two sides will be considered positive for scapular dyskinesis (Kibler, 2010). To assess dynamic movement, the "Kibler" test will be used; this involves the athlete standing while holding weights-1-2 kg for women and 3-4 kg for men-in their hands. The movement-flexion or abduction up to 120°-will be performed by raising the arm over 5 seconds and lowering it over 5 seconds. This movement is repeated 3 times. The evaluator will observe the scapulae from behind (Kibler, 2013).

Application Methods:

For the volleyball players in the trunk-training group, PNF (Proprioceptive Neuromuscular Facilitation) techniques-specifically the "lifting" and "chopping" patterns-will be employed. In this exercise, the dominant arm will follow a "flexion-abduction-external rotation" pattern, while the non-dominant arm will follow a "flexion-adduction-external rotation" pattern, both performed simultaneously. The head and neck will undergo extension (increasing the angle at the joint) and rotation to the right. Upon the command, "Follow your hands with your head and move toward my hand-up and back," the participant will lift their trunk into an upright position. Upon the command, "Follow your hands with your head and reach toward your opposite knee," the participant will flex their trunk forward against optimal resistance (a "chopping" motion) (Kaya Utlu D., 2023). For the volleyball players in the upper-extremity training group, PNF techniques will be applied to the dominant upper extremity in the "flexion-abduction-external rotation" pattern. At the start of this movement, the wrist is positioned in ulnar deviation (bending the wrist toward the little finger side), and the forearm is placed in pronation (palm facing downward). While the shoulder moves into extension (increasing the joint angle) and adduction (moving toward the midline of the body), the position of the wrist and hand is maintained. The humerus is brought across the midline, with the palm placed against the ilium (pelvic bone); this is followed by extension of the fingers and thumb, combined with radial deviation of the wrist (bending the wrist toward the thumb side). The shoulder will be brought into a position of flexion, abduction (movement away from the body's midline), and external rotation by applying optimal resistance, following the command: "Raise your hand and move your arm upward and to the side." Technically, the "rhythmic initiation" technique will be employed (Kaya Utlu D., 2023). In both groups, the Rhythmic Initiation technique will be employed; this involves rhythmic, unidirectional movements of a limb or the body, performed against an optimal level of resistance throughout the desired range of motion. This technique facilitates the learning of movement by enhancing coordination and kinesthetic awareness (Knot M., 1985). The movement will be repeated until the volleyball player's movement quality begins to deteriorate or until the player becomes fatigued.