The Impact of Blood Flow Restriction Within Warm-up.

Study Overview
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Brief Summary
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Sixty athletes will be randomized in two groups; (1) an experimental group and (2) a control group. Both groups will undergo the following procedure: Moment 1: Baseline testing: countermovement jump, 25m sprint and strength assessment of the Hamstrings and Quadriceps muscle. Short warm-up (approximately 4 minutes), which will be completed with blood flow restriction cuffs (experimental group) or without (control group) Post testing: same tests as performed in baseline. Moment 2: Baseline testing: stiffness measurements of the Biceps Femoris Long Head via Shear Wave Elastography. Short warm-up (approximately 4 minutes), which will be completed with blood flow restriction cuffs (experimental group) or without (control group) Post testing: same tests as performed in baseline. Both moments of testing as well as the order in which the performance tests take place are randomized.

Detailed Description
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Traditionally, athletes perform a warm-up program before participating in sport activities, due to its assumed beneficial effect on performance and injury prevention. However, within team sports, substitutes usually do not perform the comprehensive pre-match warm-up. In many cases, those substitute players get a very short period of time, during the game, to prepare themselves for coming on to the pitch where they immediately have to perform at a very high-intensity. Hence, this could lead to a poorer performance and a greater injury risk for those substitute players, as they did not get a decent warm-up. Therefore, new techniques are needed in order to prepare the substitute athletes optimally in a very short period of time (often within a few minutes). Consequently, the aim of this study is to investigate whether the incorporation of Blood Flow Restriction (BFR) within a warm-up routine could be of additional value. Both performance parameters and muscle stiffness will be evaluated. As Hamstring strain Injuries (HSI) are common within sports encompassing high-speed running, this muscle group will be investigated on muscle stiffness as a representation of the interventional effect on muscle stiffness. Athletes will be randomized in two groups of 30 participants (anticipated); (1) an experimental group and (2) a control group. Both groups will perform baseline testing (5x Countermovement Jump, 25m Sprint and Muscle Strength of hamstrings and Quadriceps), and a short warm-up program, followed by repeating the same tests as executed in baseline. The experimental group will receive Blood Flow Restriction within the warm-up routine, whereas the control group will do the same warm up program but without BFR. On a separate occasion, the same athletes will perform the same warm-up routine with a Shear Wave Elastographic assessment of the Biceps Femoris Long Head before and after (immediately after, after 5 minutes and once more after 10 minutes) the warm-up.

Official Title
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The Impact of Blood Flow Restriction Within Warm-up Routines on Performance and Muscle Stiffness.

Conditions
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Healthy

Intervention / Treatment
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* Device: Warm-up + Blood Flow Restriction cuff (smart-cuff pro device, acting as pressurized tourniquet)
* Other: Warm-up


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Free of pain at the moment of testing Adult (18+) Athletes (competitive team sport) Exclusion Criteria: History of a hamstring strain injury History of cardiovascular problems Recent (<1 year) trauma or surgery of the lower extremity Reduced functioning or pain in the lower extremity. Not being able to perform physical activities, for whatever (medical) reason.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Blood Flow Restriction<br>Incorporation of Blood Flow Restriction within the warm-up routine. | Device: Warm-up + Blood Flow Restriction cuff (smart-cuff pro device, acting as pressurized tourniquet)<br>* Blood Flow Restriction<br>* Other names: partial vascular occlusion;|
| Active Comparator: Control Group<br>Warm-up routine without any special intervention (no Blood Flow Restriction). | Other: Warm-up<br>* Warm-up without any special intervention (no Blood Flow Restriction)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in muscle stiffness | The stiffness of the Biceps Femoris Long Head of the dominant leg will be assessed via a Shear Wave Elastography Device (Mach 30, SuperSonic Imagine), before and immediately after the warm-up routine. The muscle stiffness will be expressed in Kilopascals (kPa). | (1) Before the warm-up routine, (2) immediately after the warm-up routine, (3) 5 minutes after the warm-up routine, and (4) 10 minutes after the warm-up routine | 
| Change in jump height | The jump height will be assessed during 5 consecutive countermovement jumps. This will be assessed with an OptoJump device. The highest jump will be taken into account. The jump height will be expressed in cm. | (1) Before the warm-up routine and (2) immediately after the warm-up routine | 
| Change in muscle strength | Muscle strength of the Hamstrings and Quadriceps muscles. Measured via a Hand Held Dynamometer. Strength will be expressed in Newton (N). | (1) Before the warm-up routine and (2) immediately after the warm-up routine | 
| Change in sprinting speed | Sprinting speed will be assessed at 5m, 10m and 25m. This via the use of timing gates. This outcome measure will be expressed in seconds (s). | (1) Before the warm-up routine and (2) immediately after the warm-up routine | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| level of readiness | Participants will be asked after the warm-up (with or without BFR) how well they feel prepared to substitute into the game on a scale from 0-100; being zero = not ready at all, 100 = totally ready | Immediately after the warm-up | 
| Change in heart rate | This parameter will be captured to track the cardiovascular answer of the body during the warm-up by using a polar watch and elastic strap with a monitor around the waist. | (1) Right before the warm up, (2) after one minute, (3) after two minutes, (4) after 3 minutes, (5) at the end of the warm up | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Shear Wave Elastography, Blood Flow Restriction, Warm-up, Performance