Healthy Volunteers (HV)
Conditions
Keywords
Nordic Hamstring Exercise, Blood Flow Restriction, Elite Adolescent Athletes, Muscle Oxygenation
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.
Detailed description
Hamstring muscles play a crucial role in sprinting, jumping, change-of-direction movements, and other high-intensity athletic activities. Nordic Hamstring Exercise (NHE) is one of the most effective eccentric strengthening exercises for improving hamstring function and reducing the risk of hamstring strain injuries. Recently, blood flow restriction (BFR) training has gained increasing attention because it may enhance metabolic stress and alter muscle oxygenation responses during exercise. However, evidence regarding the acute physiological effects of combining BFR with Nordic Hamstring Exercise in elite adolescent athletes remains limited. This study aims to compare hamstring muscle oxygenation responses during conventional Nordic Hamstring Exercise and Blood Flow Restriction Nordic Hamstring Exercise in elite adolescent athletes. A prospective crossover experimental design will be used, allowing each participant to complete both exercise conditions and serve as his or her own control. The order of the interventions will be randomized, and the two testing sessions will be separated by a 7-day washout period to minimize potential carryover effects. Elite adolescent athletes aged 14-18 years who have participated in regular training for at least three years will be recruited. During each testing session, hamstring muscle oxygen saturation (SmO₂) and total hemoglobin (tHb) responses will be continuously monitored using wearable near-infrared spectroscopy (MOXY). Measurements will include baseline SmO₂, minimum SmO₂, delta SmO₂, recovery SmO₂, baseline total hemoglobin, peak total hemoglobin, and delta total hemoglobin. Blood lactate concentration, rating of perceived exertion using the Borg Rating of Perceived Exertion Scale, exercise performance variables, and post-exercise symptoms such as muscle soreness and fatigue will also be recorded. Nordic Hamstring Exercise will be performed according to a standardized protocol under physiotherapist supervision. During the Blood Flow Restriction Nordic Hamstring Exercise condition, the same exercise protocol will be performed while individualized blood flow restriction is applied to the proximal lower extremity using a pneumatic cuff. The cuff pressure will be individualized based on participant tolerance and safety, and the intervention will be discontinued immediately if any adverse symptoms occur. The primary objective is to determine whether blood flow restriction alters acute hamstring muscle oxygenation responses during Nordic Hamstring Exercise. Secondary objectives include comparing total hemoglobin responses, blood lactate concentration, perceived exertion, exercise performance, and post-exercise recovery between the two exercise conditions. The findings of this study are expected to improve understanding of the physiological mechanisms of blood flow restriction during eccentric hamstring exercise and provide evidence for its safe and effective use in adolescent athletic populations.
Interventions
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.
OTHERBlood 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.
Sponsors
Toros University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
NONE
Intervention model description
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.
Eligibility
Sex/Gender
ALL
Age
14 Years to 18 Years
Healthy volunteers
Yes
Inclusion criteria
* 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.
Exclusion criteria
* 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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 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 | Perceived exertion will be assessed using the Borg Rating of Perceived Exertion Scale following each exercise condition. Higher scores indicate greater perceived exertion. |
| 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 | The number of Nordic Hamstring Exercise repetitions completed with the required technique will be recorded during each exercise condition. A higher number indicates better acute exercise performance. |
| Difference in Post-Exercise Hamstring Muscle Soreness Between NHE and BFR-NHE | 24 hours after each exercise session | Hamstring muscle soreness will be assessed using an 11-point Numerical Rating Scale ranging from 0, indicating no soreness, to 10, indicating the worst imaginable soreness. |
Countries
Turkey (Türkiye)
Contacts
CONTACTİdil Ünlü, Assist. Prof. Dr.
Outcome results
None listed