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

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.

• Nordic Hamstring Exercise (Behavioral): Participants will perform a supervised Nordic Hamstring Exercise program three times per week for 8 weeks in addition to their routine pole vault training. The exercise program will be progressively increased according to participant tolerance and training progression.
• Blood Flow Restriction-Assisted Nordic Hamstring Exercise (Behavioral): articipants will perform a supervised Nordic Hamstring Exercise program combined with individualized blood flow restriction training three times per week for 8 weeks in addition to their routine pole vault training. Blood flow restriction will be applied using pneumatic cuffs at a predetermined percentage of arterial occlusion pressure.

Primary outcomes

• Hamstring Muscle Strength [Baseline and 8 weeks]: Isometric hamstring muscle strength will be assessed bilaterally using a MicroFET2 handheld dynamometer. Three measurements will be recorded and the average value will be used for analysis.
• Hamstring Muscle Thickness [Baseline and 8 weeks]: Hamstring muscle thickness will be evaluated bilaterally using ultrasonography. Three measurements will be obtained and averaged.
• Hamstring Cross-Sectional Area [Baseline and 8 weeks]: Cross-sectional area of the hamstring muscle will be assessed bilaterally using ultrasonography.

Secondary outcomes

• 30-Meter Sprint Performance [Baseline and 8 weeks]: Sprint performance will be assessed using a 30-meter sprint test. The average of three trials will be used for analysis.

Sex: Female, ages: 12 Years to 18 Years, accepts healthy volunteers

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.

• Results publication: Ripley NJ, Cuthbert M, Comfort P, McMahon JJ. Effect of additional Nordic hamstring exercise or sprint training on the modifiable risk factors of hamstring strain injuries and performance. PLoS One. 2023 Mar 2;18(3):e0281966. doi: 10.1371/journal.pone.0281966. eCollection 2023. PMID 36862645
• Results publication: Vianna KB, Rodrigues LG, Oliveira NT, Ribeiro-Alvares JB, Baroni BM. A Preseason Training Program With the Nordic Hamstring Exercise Increases Eccentric Knee Flexor Strength and Fascicle Length in Professional Female Soccer Players. Int J Sports Phys Ther. 2021 Apr 1;16(2):459-467. doi: 10.26603/001c.19452. PMID 33842041