The purpose of this randomized controlled trial is to compare the effects of Nordic Hamstring Exercise (NHE) and Blood Flow Restriction-assisted Nordic Hamstring Exercise (BFR-NHE) on hamstring muscle strength, muscle morphology, and functional performance in elite adolescent female pole vaulters. Thirty-six athletes aged 12-18 years will be randomly assigned to a Nordic Hamstring Exercise group, a Blood Flow Restriction-assisted Nordic Hamstring Exercise group, or a control group. Intervention groups will participate in supervised exercise training three times per week for eight weeks, while the control group will continue routine sports training. Outcomes will be assessed before and after the intervention period.