Effects of muscle warm-up phases on proprioception, vertical jump, agility, and balance in elite adolescent soccer players: a repeated-measures experimental study

OBJECTIVES: The aim of this study is to investigate the effects of different muscle warm-up phases on knee joint proprioception, vertical jump, agility, and balance in professional youth athletes. METHODS: Twenty-five professional adolescent football players under the age of 18 (mean age: 16.5 ± 1.2 years) were included in the study (n=25). Dominant knee joint proprioception was measured at 30° using a digital inclinometer. Dynamic balance was assessed using the Y-balance test (in anterior, posteromedial, and posterolateral directions), explosive power was evaluated with the Sargent vertical jump test, and agility was measured using the T-test. All assessments were conducted during three muscle warm-up phases (rest, warm-up, and post-training). RESULTS: The analysis revealed significant differences in all parameters depending on the muscle's warm-up state (p<0.001). Proprioception, explosive power, agility, and dynamic balance were measured at their best when the muscles were warmed up. Proprioception was found to be weakest in the fatigued muscle condition (2.42°). Explosive power and dynamic balance were lowest in the resting muscle condition. Agility did not differ between the resting and fatigued conditions (p=0.874). CONCLUSIONS: Muscle warm-up phases positively influence proprioceptive accuracy, agility, and balance in elite youth soccer players, whereas fatigue impairs these parameters. These findings suggest that optimal warm-up protocols should be incorporated to enhance performance and reduce injury risk. TRIAL REGISTRATION: This study was retrospectively registered with ClinicalTrials.gov on 12/15/2025 (ID: NCT07284706).