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Resistance training has been widely performed due to its health benefits. However, performing this training at high intensity causes significant muscle stress, leading to fatigue and compromising performance. It is essential to implement effective recovery strategies to optimize physiological adaptations. Among the accessible techniques, blood flow restriction (BFR) has shown promise for its potential to accelerate muscle recovery.
A randomized clinical trial will be conducted with 40 men and 40 women allocated to one of four groups: i) BFR using 80% of total occlusion pressure (TOP) [BFR-80%]; ii) BFR using 60% of total occlusion pressure (TOP) [BFR-60%]; iii) BFR using 10 mmHg (BFR-10 mmHg); and iv) control (CON). All groups will undergo initial assessments, followed by the muscle stress protocol, and all outcomes will be collected again. Subsequently, the intervention to which they were previously randomized will be performed, and finally, subsequent assessments will be conducted immediately, 24, 48, and 72 hours after exercise. The outcomes assessed will be, in order: pain using the Numerical Rating Scale (NRS), perception of recovery and discomfort using the Likert scale, and perception of effort using the Borg scale (CR-10), cellular integrity vectors using bioelectrical impedance analysis (BIA), pain threshold using a pressure algometer, muscle tone, stiffness, and elasticity using myotonometry, quadriceps muscle strength test using a digital dynamometer, muscle power test using the Squat Jump test, and a single-leg jump functional test.
Participants will be duly informed about the procedures and objectives of this study, and after agreeing, will sign a free and informed consent form, thus becoming effectively part of it. In the consent form, participants will be asked if they agree to the use of their data should they choose to withdraw from the study. Participants will also be asked for permission for the research team to share relevant data with people from the universities participating in the research or regulatory authorities, when relevant, while preserving the participant's identity. The study will be submitted for review and approval to the Research Ethics Committee of FCT/UNESP, Presidente Prudente, SP, Brazil and will be registered on ClinicalTrials.gov.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Blood flow restriction with 80% occlusion | Experimental | Will perform an BFR intervention using 80% of the total occlusion pressure (TOP) continuously for 20 minutes. |
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| Blood flow restriction with 60% occlusion | Experimental | Will perform an BFR intervention using 60% of the total occlusion pressure (TOP) continuously for 20 minutes. |
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| Blood flow restriction with 10 mmHg of occlusion pressure | Placebo Comparator | The intervention will be performed with BFR using 10 mmHg of occlusion pressure continuously for 20 minutes. |
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| Control | No Intervention | It will remain at rest for 20 minutes without using BFR. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| BFR-80% | Device | Will perform the intervention with BFR using 80% of the total occlusion pressure (TOP) continuously for 20 minutes. |
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| Measure | Description | Time Frame |
|---|---|---|
| Lower limb muscle power | Muscle power will be assessed through the Squat Jump test using a contact platform (Multisprint). Participants will begin in a 90° knee flexion position (verified with a goniometer), with hands on hips, and will perform a vertical jump without countermovement. Variables to be analyzed will include jump height, modified reactive strength index, jump power, and take-off moment. | Change from baseline at 72 hours after exercise |
| Lower limb muscle function | Muscle function will be assessed through the single leg hop functional test sing a measuring tape in centimeters. The participant will be positioned standing on a flat surface, barefoot, and with their hands on their waist. They will be asked to perform a horizontal jump with the greatest possible reach using only one lower limb (test performed unilaterally). The contralateral limb will remain flexed without touching the ground during the execution. After the jump, the participant must maintain balance for at least two seconds without losing stability or moving the landing foot. The jump distance will be measured in centimeters from the toe of the supporting foot (before the jump) to the heel at the moment of landing, using a measuring tape. | Change from baseline at 72 hours after exercise |
| Isometric strenght of quadriceps and hamstring muscle | The isometric peak torque of the quadriceps and hamstring will be measured using a digital handheld dynamometer (DD-300, Instrutherm). For the quadriceps strength assessment, the participant will be seated in a chair with their knee bent at 90° and instructed to push maximally against the dynamometer. To measure hamstring strength, the participant will be positioned in a prone position with their knee flexed at 90º and will be instructed to push maximally against the dynamometer. Three attempts will be performed with a 1-minute rest interval. The highest value will be used for analysis. | Change from baseline at 72 hours after exercise |
| Muscle soreness and pain threshold |
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| Measure | Description | Time Frame |
|---|---|---|
| Occlusion pressures (AOP) | To determine the AOP, the Doppler equipment transducer will be used, which will be positioned over the posterior tibial artery to capture the auscultatory pulse. A blood pressure cuff will be fixed to the participant's thigh close to the region of the inguinal fold of the dominant limb, and then with the inflatable region of the cuff on the medial portion of the thigh covering the femoral artery, it will be progressively inflated, waiting 15 seconds every 30 mmHg until the point at which the auscultatory pulse of the tibial artery is interrupted. |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Franciele Marques Vanderlei PhD | Contact | +55 (18) 3229-5824 | franmvanderlei@gmail.com |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Franciele Marques Vanderlei | Recruiting | Presidente Prudente | São Paulo | 19060-900 | Brazil |
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| BFR-60% | Device | Will perform the intervention with BFR using 60% of the total occlusion pressure (TOP) continuously for 20 minutes. |
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| BFR-10mmHg | Other | Will perform the intervention with BFR using 10 mmHg of occlusion pressure continuously for 20 minutes. |
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Muscle soreness will be assessed using a Numeric Pain Rating Scale (0-10). Pain threshold will be measured with a pressure algometer (FPX 50/220; Wagner) at four sites: biceps femoris and rectus femoris. Measurements will be recorded in kgf and will not exceed 2.55 kgf.
| Change from baseline at 72 hours after exercise |
| Perceived exertion, recovery, and discomfort | Perceived exertion, recovery, and discomfort will be measured using the Borg CR-10 scale (0-10). Participants will rate: (1) exertion as whole-body effort, (2) discomfort as muscular sensations in the lower limbs, and (3) recovery as general physical and psychological recovery. Values will be individually recorded at each time point. | Change from baseline at 72 hours after exercise |
| Myotonometry | Muscle tone, stiffness, and elasticity will be measured using the MyotonPRO device. The probe will be positioned perpendicularly over the following sites: biceps femoris and rectus femoris. The device will apply a 0.18 N pre-load and a 0.40 N impulse to induce tissue oscillation for measurement. | Change from baseline at 72 hours after exercise |
| Bioelectrical impedance analysis | Bioimpedance will be measured using a tetrapolar device (BIA Analyzer, 50 kHz, 800 µA). Electrodes will be positioned on the biceps femoris and rectus femoris. Analyzed variables will include resistance (R), reactance (Xc), phase angle (PhA), and tolerance ellipse, via Bioscan software. | Change from baseline at 72 hours after exercise |
| Baseline |