Acute High Intensity Interval Training and Blood Flow Restriction

Study Overview
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Brief Summary
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The study aims to look at the blood flow restriction (BFR) + high intensity interval training (HIIT) variables to induce an optimal acute training stimulus (i.e., acute responses in main outcome measures of muscular activation, muscular deoxygenation, and secondary outcome measures of heart rate (HR), blood lactate (bLa), subjective ratings of perceived exertion and discomfort) The hypotheses for this study are: (i) BFR increases muscular deoxygenation, muscular activation when HIIT exercise is of the same intensity, (ii) however, comparing between a lower BFR + HIIT exercise intensity (e.g. 80% V̇O2max) and higher HIIT exercise intensity (e.g. 100% V̇O2max), muscular deoxygenation and activation will be similar but HR will be lower in the BFR + HIIT condition.

Detailed Description
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This study revolves around the optimisation of blood flow restriction (BFR) and high-intensity interval training (HIIT) protocols for the racket sport athlete. The study aims to look at the BFR + HIIT variables to induce an optimal acute training stimulus. This can be achieved with the consideration of two main research questions: (i) What is the ideal combination of BFR cuff pressure and exercise intensity (i.e. cycling) to elicit favourable training stimuli, i.e., acute responses in main outcome measures of muscular activation, muscular deoxygenation, and secondary outcome measures of heart rate (HR), blood lactate (bLa), subjective ratings of perceived exertion and discomfort?; (ii) How does BFR + HIIT compare with traditional HIIT at a similar or higher exercise intensity in terms of these acute responses? The hypotheses for this study are: (i) BFR increases muscular deoxygenation, muscular activation when HIIT exercise is of the same intensity, (ii) however, comparing between a lower BFR + HIIT exercise intensity (e.g. 80% V̇O2max) and higher HIIT exercise intensity (e.g. 100% V̇O2max), muscular deoxygenation and activation will be similar but HR will be lower in the BFR + HIIT condition.

Official Title
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Acute Responses to High-intensity Interval Exercise (HIIE) and Blood Flow Restriction (BFR)

Conditions
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Activity, Motor

Intervention / Treatment
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* Other: Active Comparator: HIIT Control
* Other: Experimental: HIIT + BFR between cycling sets
* Other: Experimental: HIIT + BFR moderate occlusion during cycling
* Other: Experimental: HIIT + BFR high occlusion during cycling


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male Age: 18-40 years Competed in competitive varsity sports (endurance, tennis, badminton, squash, football, basketball, etc.) at the varsity/club level Actively training for at least 2 sessions (1 - 1.5h) per week Healthy (free from illnesses) and no musculoskeletal injuries for the past 6 months No history of cardiometabolic, vascular diseases or similar conditions (high blood pressure, peripheral vascular diseases, heart diseases, metabolic syndrome, diabetes, stroke, etc.). Pass pre-participation health screening tests - Physical Activity Readiness Questionnaire for Everyone (PAR-Q+) and Australian Institute of Sport (AIS) Blood Flow Restriction (BFR) pre-screening questionnaire (no history of any risk factors). Maximal oxygen uptake (VO2max) of ≥40mmol/min/kg during a maximal aerobic cycling test. Non-smoker Drink alcohol less than 3 times each week and less than 3 drinks each time Exclusion Criteria: Any diagnosed form of cardiometabolic disease (CVD, diabetes, metabolic syndrome, hypertension) Any symptoms contraindication of exercise testing (eg chest pains) Any balance or dizziness problems Any chronic medical conditions (whether medicated or not) Any bone joint problems Any Physician diagnosed contraindications to exercise

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: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: HIIT Control<br>High intensity interval cycling | Other: Active Comparator: HIIT Control<br>* Complete 3 sets of five repetitions of 30 seconds cycling at 100% of maximal aerobic power with 30 seconds of active unloaded recovery between repetitions; 3 minutes of passive rest between sets.<br>|
| Experimental: HIIT + BFR between cycling sets<br>High intensity interval cycling with blood flow restriction applied between sets of cycling | Other: Experimental: HIIT + BFR between cycling sets<br>* Complete 3 sets of five repetitions of 30 seconds cycling at 100% of maximal aerobic power with 30 seconds of active unloaded recovery between repetitions; 3 minutes of passive rest between sets. Blood flow restriction is applied for 2 minutes during the passive rest at 80% of limb occlusion pressure.<br>|
| Experimental: HIIT + BFR moderate occlusion during cycling<br>High intensity interval cycling with moderate blood flow restriction applied during cycling | Other: Experimental: HIIT + BFR moderate occlusion during cycling<br>* Complete 3 sets of five repetitions of 30 seconds cycling at 70% of maximal aerobic power with 30 seconds of active unloaded recovery between repetitions; 3 minutes of passive rest between sets. Blood flow restriction is applied during and between exercise repetitions at 50% of limb occlusion pressure and deflated during passive rest periods.<br>|
| Experimental: HIIT + BFR high occlusion during cycling<br>High intensity interval cycling with high blood flow restriction applied during cycling | Other: Experimental: HIIT + BFR high occlusion during cycling<br>* Complete 3 sets of five repetitions of 30 seconds cycling at 70% of maximal aerobic power with 30 seconds of active unloaded recovery between repetitions; 3 minutes of passive rest between sets. Blood flow restriction is applied during and between exercise repetitions at 80% of limb occlusion pressure and deflated during passive rest periods.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate |  | Measured and compared between each acute arm (condition) | 
| Blood lactate concentration |  | Measured and compared between each acute arm (condition) | 
| Muscle activation | Surface electromyography of the vastus lateralis and biceps femoris muscles to determine electrical activity of the motor units (physiological parameter) | Measured and compared between each acute arm (condition) | 
| Muscle oxygenation | Near infra-red spectroscopy to examine regional tissue (the vastus lateralis muscle) oxygenation i.e, the percentage of haemoglobin and deoxyhaemoglobin (physiological parameter) | Measured and compared between each acute arm (condition) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rating of perceived exertion | Borg Rating of Perceived Exertion scale 6-20 (6 = no exertion at all; 20 = maximal exertion) | Measured and compared between each acute arm (condition) | 
| Exertion and Pain scale | Borg Category-Ratio (CR) 10 scale (0 = No exertion at all; 10 = Maximal) | Measured and compared between each acute arm (condition) |