Frontal Plane Knee Projection Angle and Functional Performance in Adolescent Female Volleyball Players

Frontal plane projection angle (FPPA) was assessed using SparkMotion software. FPPA was calculated from the angle between a line from the anterior superior iliac spine (ASIS) to the midpoint of the patella and a line from the patellar midpoint to the midpoint between the medial and lateral malleoli; this value was subtracted from 360° to obtain FPPA. Values ≥195° were descriptively classified as increased FPPA. Frontal-plane video was recorded using an iPad mounted on a tripod positioned 3 m from the participant and 1 m above the ground. Participants performed a single-leg squat with arms crossed over the chest at a metronome-paced tempo (2 s descent, 2 s ascent). FPPA was measured at the deepest squat position reached while maintaining balance. After 3 practice trials, 5 consecutive recorded squats were performed, and the third trial was used for analysis.

Dynamic balance was assessed using the Lower Quarter Y-Balance Test (YBT-LQ). This standardized test evaluates reach distance in the anterior, posteromedial, and posterolateral directions while maintaining single-leg stance. Reach distances were recorded to the nearest 0.5 cm using the Y Balance Test kit. Before testing, leg length was measured from the anterior superior iliac spine (ASIS) to the distal tip of the medial malleolus, and results were normalized to leg length. Participants completed 6 practice trials before testing, followed by 3 valid trials in each direction. Invalid trials were repeated, and the mean of the 3 valid trials for each direction was used for analysis. The composite score was calculated by dividing the sum of the 3 reach distances by 3 times leg length and multiplying by 100.

Agility was assessed using the T-Test. The test course was set up in a T shape with 4 cones: cone A was positioned 9.14 m from the center cone B, and cones C and D were placed 4.57 m to the left and right of cone B. Participants started at cone A, sprinted to cone B, shuffled laterally to touch cone C, then shuffled to touch cone D, returned to cone B, and backpedaled to cone A to complete the test. Time was recorded using a photocell timing system. After 2 familiarization trials, participants performed 3 valid trials with 3 minutes of rest between trials, and the best time was used for analysis.

nkle dorsiflexion mobility was assessed using the Weight-Bearing Lunge Test (WBLT). Participants were positioned facing a wall in a tandem stance, with the tested foot aligned perpendicular to the wall and the non-tested rear heel lifted. They were instructed to place their hands on the wall and move the front knee toward it while keeping the tested heel in contact with the ground. The foot was moved away from the wall in 1 cm increments until the maximum distance at which the knee could still touch the wall without heel lift was identified. The farthest valid distance between the great toe and the wall was measured in centimeters. Three valid trials were recorded for each lower extremity, and the mean value was used for analysis. Trials with heel lift, marked lower-extremity compensations, or loss of proper test position were repeated.