Blood Flow Restriction During Nordic Hamstring Exercise in Elite Adolescent Athletes

NCT07715786 | Recruiting

• 1 other identifier: 06/101-23.06.2026
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

This crossover experimental study aims to compare acute hamstring muscle oxygenation responses during Nordic Hamstring Exercise (NHE) and Blood Flow Restriction Nordic Hamstring Exercise (BFR-NHE) in elite adolescent athletes. Participants will complete both exercise conditions in a randomized order separated by a 7-day washout period. Muscle oxygen saturation will be assessed using near-infrared spectroscopy (MOXY), together with total hemoglobin responses, blood lactate concentration, perceived exertion, and exercise performance variables. The findings may improve understanding of the physiological effects of blood flow restriction during eccentric hamstring exercise in adolescent athletes.

Conditions

Healthy Volunteers (HV)

Keywords

Nordic Hamstring Exercise; Blood Flow Restriction; Elite Adolescent Athletes; Muscle Oxygenation

Outcome Measures

Primary Outcomes (6)

• Difference in Change in Hamstring Muscle Oxygen Saturation (Delta SmO₂) Between NHE and BFR-NHE

  Hamstring muscle oxygen saturation will be continuously measured using a wearable near-infrared spectroscopy device (MOXY) during conventional Nordic Hamstring Exercise and Blood Flow Restriction Nordic Hamstring Exercise. Delta SmO₂ will be calculated as the difference between baseline SmO₂ and the minimum SmO₂ recorded during each exercise condition. Greater negative change indicates greater muscle deoxygenation.

  During each exercise session, with the two sessions separated by a 7-day washout period

• Difference in Minimum Hamstring Muscle Oxygen Saturation Between NHE and BFR-NHE

  The minimum hamstring muscle oxygen saturation value (SmO₂, %) recorded during each exercise condition will be obtained using the MOXY near-infrared spectroscopy device. Lower values indicate greater muscle deoxygenation.

  During each exercise session, with the two sessions separated by a 7-day washout period

• Difference in Hamstring Muscle Oxygen Saturation During Recovery Between NHE and BFR-NHE

  Hamstring muscle oxygen saturation (SmO₂, %) will be recorded during the post-exercise recovery period following each exercise condition using the MOXY device.

  Immediately after each exercise session during the recovery period, with sessions separated by a 7-day washout period

• Difference in Peak Hamstring Total Hemoglobin Between NHE and BFR-NHE

  Peak total hemoglobin concentration in the hamstring muscle will be recorded during each exercise condition using the MOXY near-infrared spectroscopy device.

  During each exercise session, with the two sessions separated by a 7-day washout period.

• Difference in Change in Hamstring Total Hemoglobin Between NHE and BFR-NHE

  Change in total hemoglobin will be calculated as the difference between baseline total hemoglobin and peak total hemoglobin recorded during each exercise condition using the MOXY device.

  During each exercise session, with the two sessions separated by a 7-day washout period.

• Difference in Post-Exercise Blood Lactate Concentration Between NHE and BFR-NHE

  Blood lactate concentration will be measured using a portable lactate analyzer following each exercise condition and reported in mmol/L. Higher values indicate a greater acute metabolic response.

  Immediately after each exercise session, with the two sessions separated by a 7-day washout period

Secondary Outcomes (3)

• Difference in Rating of Perceived Exertion Between NHE and BFR-NHE

  Immediately after each exercise session, with the two sessions separated by a 7-day washout period

• Difference in the Number of Successfully Completed Nordic Hamstring Exercise Repetitions Between Conditions

  During each exercise session, with the two sessions separated by a 7-day washout period

• Difference in Post-Exercise Hamstring Muscle Soreness Between NHE and BFR-NHE

  24 hours after each exercise session

Study Arms (2)

BFR NHE-NHE

EXPERIMENTAL

Participants randomized to this sequence will perform conventional Nordic Hamstring Exercise during the first testing session. Following a 7-day washout period, they will perform Nordic Hamstring Exercise with blood flow restriction during the second testing session.

Other: Nordic Hamstring Exercise; Other: Blood Flow Restriction Nordic Hamstring Exercise

NHE-BFR NHE

EXPERIMENTAL

Participants randomized to this sequence will perform Nordic Hamstring Exercise with blood flow restriction during the first testing session. Following a 7-day washout period, they will perform conventional Nordic Hamstring Exercise during the second testing session.

Other: Nordic Hamstring Exercise; Other: Blood Flow Restriction Nordic Hamstring Exercise

Interventions

Nordic Hamstring Exercise OTHER

Participants will perform a standardized Nordic Hamstring Exercise protocol under physiotherapist supervision. From a kneeling position with the ankles stabilized, participants will lower the trunk forward in a controlled manner while maintaining alignment of the trunk and hips.

BFR NHE-NHE; NHE-BFR NHE

Blood Flow Restriction Nordic Hamstring Exercise OTHER

Participants will perform the same standardized Nordic Hamstring Exercise protocol while individualized blood flow restriction is applied using a pneumatic cuff positioned on the proximal lower extremity.

BFR NHE-NHE; NHE-BFR NHE

Eligibility Criteria

• Age: 14 Years - 18 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Elite adolescent athletes aged 14 to 18 years.
• Licensed athletes with at least 3 years of regular sports participation.
• Currently participating in a regular weekly training program.
• Physically able to complete the Nordic Hamstring Exercise and study testing protocol.
• Willing to participate in the study.
• Able to provide written informed consent.
• For participants younger than 18 years, written informed consent provided by a parent or legal guardian and assent provided by the participant.

You may not qualify if:

• Hamstring injury within the previous 6 months.
• Lower extremity surgery within the previous 6 months.
• Current lower extremity pain or musculoskeletal injury that may interfere with exercise performance.
• Cardiovascular, vascular, neurological, or other medical conditions that may contraindicate blood flow restriction exercise.
• Presence of skin lesions or conditions preventing placement of the blood flow restriction cuff or MOXY sensor.
• Inability to complete either exercise condition or follow the study protocol.

Sponsors & Collaborators

• Toros University: lead

Study Sites (1)

Adana Olympic Preparation Center

Adana, Turkey (Türkiye)

RECRUITING

Central Study Contacts

İdil Ünlü, Assist. Prof. Dr.

CONTACT

+90 506 515 66 22; idil.unlu@toros.edu.tr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assist. Prof. Dr.

Model Details: Participants will complete both intervention conditions in a randomized crossover design. Each participant will perform conventional Nordic Hamstring Exercise (NHE) and Blood Flow Restriction Nordic Hamstring Exercise (BFR-NHE) in a randomized order. The two testing sessions will be separated by a 7-day washout period to minimize potential carryover effects. Each participant will serve as his or her own control.

Study Record Dates

• First Submitted: July 13, 2026
• First Posted: July 20, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): August 1, 2027
• Last Updated: July 20, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)