Physiological Outcomes of High-intensity Interval Training With Post-exercise Blood Flow Restriction

This research study revolves around the physiological outcomes of using post-exercise blood flow restriction (BFR) with high-intensity interval exercise training (HIIT), specifically high intensity short interval training (ST) protocol of 30s work, 30s rest, for the recreational endurance athlete. In previous research, it has been shown that using BFR during rest intervals of a ST protocol would elicit greater physiological stresses in terms of higher heart rate, greater muscle activation, reduced oxygenation within the muscle tissue during exercise, and increased blood lactate post-exercise as compared with the control condition. However, the physiological outcomes of this type of training method over a longer-term (9 sessions over 3 weeks) have not been explored. The main aims of this study is to compare the physiological outcomes, - (i) aerobic performance outcomes, and (ii) anaerobic and muscular performance outcomes - between 2 groups of participants after either undergoing 3 weeks of ST + post-exercise BFR (BFR-ST) or traditional ST . The hypotheses for this study are: the BFR-ST group would experience a (i) greater improvement in maximal aerobic capacity, function and time trial performance and, (ii) greater improvement in anaerobic power and capacity as well as muscular strength and power, as compared with the ST group.

Inclusion criteria

• Male
• 18-40 years
• Actively performing endurance exercise (running or cycling) 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 (e.g., high blood pressure, peripheral vascular diseases, heart diseases, metabolic syndrome, diabetes, stroke, etc.).
• Pass the pre-participation health screening tests - Physical Activity Readiness Questionnaire for Everyone (PAR-Q+) and Australian Institute of Sport Blood Flow Restriction (AIS BFR) pre-screening questionnaire (no history of any risk factors).
• Achieve a maximum oxygen uptake (VO2max) of ≥40ml/kg/min during a maximal aerobic power cycling screening test.
• Non-smoker
• Drink alcohol less than 3 times each week and less than 3 drinks each time

Exclusion criteria

• Persons with any form of illnesses and/or musculoskeletal injuries for the past 6 months
• Any history of cardiometabolic, vascular diseases or similar conditions which may worsen with the use of blood flow restriction during exercise
• Fail the pre-participation health screening tests
• Below 40ml/kg/min VO2max during maximal aerobic power cycling test
• Smoker
• Consumption of alcohol beyond that stated in the inclusion criteria.
• History of asthma or taking medication for asthma.