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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Nordic Hamstring Exercise | Experimental | Participants will perform a supervised Nordic Hamstring Exercise program three times per week for 8 weeks in addition to their routine pole vault training. |
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| Blood Flow Restriction-Assisted Nordic Hamstring Exercise | Experimental | Participants will perform Nordic Hamstring Exercise combined with blood flow restriction training three times per week for 8 weeks in addition to their routine pole vault training. |
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| Control | No Intervention | Participants will continue their routine sports training without additional hamstring-specific exercise intervention. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 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. |
| Measure | Description | Time Frame |
|---|---|---|
| Hamstring Muscle Strength | 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. | Baseline and 8 weeks |
| Hamstring Muscle Thickness | Hamstring muscle thickness will be evaluated bilaterally using ultrasonography. Three measurements will be obtained and averaged. | Baseline and 8 weeks |
| Hamstring Cross-Sectional Area | Cross-sectional area of the hamstring muscle will be assessed bilaterally using ultrasonography. | Baseline and 8 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| 30-Meter Sprint Performance | Sprint performance will be assessed using a 30-meter sprint test. The average of three trials will be used for analysis. | Baseline and 8 weeks |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| İdil Esin Ünlü, Assist. Prof. Dr. | Contact | +90 506 515 66 22 | idil.unlu@toros.edu.tr |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Adana Olympic Preparation Center | Recruiting | Adana | Turkey (Türkiye) |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 36862645 | Result | 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. | |
| 33842041 | Result | 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. |
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Participants will be allocated to one of three parallel groups: Nordic Hamstring Exercise, Blood Flow Restriction-assisted Nordic Hamstring Exercise, or control. Intervention groups will complete supervised training three times weekly for eight weeks, while the control group will continue routine training. Outcomes will be assessed before and after the intervention period.
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| 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. |
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