Nordic vs Blood Flow Restriction Nordic Exercise in Elite Female Pole Vaulters

Effects of Nordic Hamstring Exercise and Blood Flow Restriction-Assisted Nordic Hamstring Exercise on Hamstring Strength, Muscle Morphology and Functional Performance in Elite Adolescent Female Pole Vaulters: A Randomized Controlled Trial

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.

Hamstring muscles play a crucial role in sprinting, acceleration, deceleration, and explosive athletic performance. Nordic Hamstring Exercise is widely recommended for increasing eccentric hamstring strength and reducing injury risk. However, evidence regarding the additional effects of blood flow restriction during Nordic Hamstring Exercise is limited, particularly in elite adolescent female athletes.

This randomized controlled trial aims to investigate whether adding blood flow restriction to Nordic Hamstring Exercise enhances adaptations in hamstring muscle strength, muscle morphology, and functional performance compared with conventional Nordic Hamstring Exercise and routine training alone.

Thirty-six elite adolescent female pole vaulters aged 12-18 years will be recruited from the Turkish Olympic Preparation Center. Participants will be allocated using block randomization into three groups:

Nordic Hamstring Exercise Group Blood Flow Restriction Nordic Hamstring Exercise Group Control Group Intervention groups will perform supervised exercise sessions three times weekly for eight weeks. The control group will continue regular training activities without additional hamstring-specific intervention.

Assessments will include hamstring muscle strength measured with a MicroFET2 handheld dynamometer, muscle morphology assessed using ultrasonography, and functional performance evaluated using a 30-meter sprint test.

Inclusion Criteria:

• Female athletes aged between 12 and 18 years.
• Elite pole vault athletes actively participating in organized training and competition.
• Minimum of 1 year of regular pole vault training experience.
• Participation in regular training at least 3 times per week.
• Ability to participate in an 8-week exercise program.
• Written informed assent from the athlete and written informed consent from a parent or legal guardian.

Exclusion Criteria:

• Any lower extremity musculoskeletal injury within the previous 6 months.
• Previous hamstring muscle surgery.
• Current pain or injury limiting sports participation.
• Neurological disorders affecting movement or balance.
• Cardiovascular conditions contraindicating exercise training or blood flow restriction.
• Any contraindication to blood flow restriction training.
• Participation in another structured hamstring strengthening program during the study period.
• Inability or unwillingness to comply with study procedures.