Blood Flow Restriction During Nordic Hamstring Exercise in Elite Adolescent Athletes

Condition(s) studied

Investigational drug(s) / intervention(s)

Nordic Hamstring Exercise: 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.

Blood Flow Restriction Nordic Hamstring Exercise: 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.

Study 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.

Eligibility

Primary outcome measure(s)

• Difference in Change in Hamstring Muscle Oxygen Saturation (Delta SmO₂) Between NHE and BFR-NHE — During each exercise session, with the two sessions separated by a 7-day washout period
  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.
• Difference in Minimum Hamstring Muscle Oxygen Saturation Between NHE and BFR-NHE — During each exercise session, with the two sessions separated by a 7-day washout period
  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.
• Difference in Hamstring Muscle Oxygen Saturation During Recovery Between NHE and BFR-NHE — Immediately after each exercise session during the recovery period, with sessions separated by a 7-day washout period
  Hamstring muscle oxygen saturation (SmO₂, %) will be recorded during the post-exercise recovery period following each exercise condition using the MOXY device.
• Difference in Peak Hamstring Total Hemoglobin Between NHE and BFR-NHE — During each exercise session, with the two sessions separated by a 7-day washout period.
  Peak total hemoglobin concentration in the hamstring muscle will be recorded during each exercise condition using the MOXY near-infrared spectroscopy device.
• Difference in Change in Hamstring Total Hemoglobin Between NHE and BFR-NHE — During each exercise session, with the two sessions separated by a 7-day washout period.
  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.
• Difference in Post-Exercise Blood Lactate Concentration Between NHE and BFR-NHE — Immediately after each exercise session, with the two sessions separated by a 7-day washout period
  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.

Trial sites (1)

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