FIFA 11+ in Young Female Volleyball Players

Injury Incidence

All sports-related injuries occurring during the 8-week pre-intervention control period and the 8-week FIFA 11+ exercise intervention period will be prospectively recorded. Injury incidence will be calculated as the number of new injuries occurring during each study period. The anatomical location, type, severity, mechanism, and time-loss associated with each injury will also be documented.

Re-Injury Anxiety Inventory Scores

Re-injury anxiety will be assessed using the Re-Injury Anxiety Inventory (RIAI). The inventory consists of two subscales: anxiety related to the rehabilitation process (RIAI-R) and anxiety related to returning to sport or competition (RIAI-RE). Each item is scored on a 4-point scale ranging from 0 ("Not at all") to 3 ("Very much"). The RIAI-R subscale includes 13 items, with total scores ranging from 0 to 39. The RIAI-RE subscale includes 15 items, with total scores ranging from 0 to 45. Higher scores indicate greater anxiety about sustaining another injury during rehabilitation or returning to sport. Subscale scores will be calculated separately according to the established scoring procedure, including reverse scoring of the relevant items.

Daily Wellness Score

Athletes' daily wellness status will be assessed using a wellness questionnaire based on the Hooper Index. The questionnaire evaluates five parameters: sleep quality, fatigue, muscle soreness, stress, and mood. Each parameter will be self-rated on a scale from 1 to 10. Individual parameter scores and the total wellness score will be recorded to monitor athletes' daily physical and psychological status. Higher scores will be interpreted according to the direction of the scoring system specified in the study protocol.

Single-Leg Hop for Distance Test

Lower-extremity functional performance will be assessed using the Single-Leg Hop for Distance Test. The athlete will stand on the test limb and perform a maximal forward hop, aiming to cover the greatest possible distance while landing on the same limb and maintaining balance. The distance from the starting line to the point of heel contact at landing will be measured in centimeters. Three valid trials will be performed for each limb, and the longest distance will be recorded. A trial will be considered invalid if the athlete loses balance, touches the ground with the opposite foot, or takes an additional step after landing. Higher values indicate better functional performance.

Session Rating of Perceived Exertion and Internal Training Load

Perceived exertion will be assessed after each training session using the Borg Category-Ratio 10 (CR-10) Scale. Athletes will rate their overall perceived exertion on a scale from 0 to 10, where 0 indicates "no exertion" and 10 indicates "maximal exertion." The session rating of perceived exertion (session-RPE) method will be used to calculate internal training load by multiplying the athlete's RPE score by the duration of the training session in minutes. Higher values indicate greater internal training load.

Training Session Duration

Training session duration will be recorded as the total time, in minutes, during which athletes actively participate in the main training component. Warm-up and cool-down periods will not be included. In addition, the total duration of moderate- and high-intensity activities performed during each session will be recorded separately as "fitness/aerobic minutes" to provide a more detailed estimate of the athletes' aerobic training exposure and internal workload.

Y-Balance Test Composite and Directional Reach Scores

Dynamic balance will be assessed using the Y-Balance Test. While standing on the test limb, the athlete will reach as far as possible with the opposite limb in the anterior, posteromedial, and posterolateral directions. The hands will remain on the hips, and the stance foot must remain stationary throughout the test. Three valid trials will be performed in each direction, and the maximum reach distance will be recorded in centimeters. Reach distances will be normalized to limb length when appropriate. A trial will be considered invalid if the athlete loses balance, moves the stance foot, places weight through the reaching foot, or fails to return to the starting position under control. Directional reach scores and the composite score will be calculated separately. Higher scores indicate better dynamic balance performance.