Feasibility of Aerobic Exercise With Blood Flow Restriction Training in People Living With Type 2 Diabetes

Individuals with type 2 diabetes (T2D) display reduced cardiorespiratory fitness, which is a strong predictor of premature mortality and T2D-related complications. Aerobic training (AT) enhances cardiorespiratory fitness and is considered a cornerstone in the management and treatment of T2D. Emerging data suggest that AT combined with blood flow restriction (AT+BFR) training, could potentially enhance cardiorespiratory fitness faster than typical AT in healthy individuals. However, the feasibility of AT+BFR in individuals with T2D and its impact on cardiorespiratory fitness have yet to be determined.

Therefore, the primary objective of this study is to test the feasibility of a 6-week AT+BFR training intervention in individuals with T2D. The secondary objective is to establish preliminary effect sizes for the efficacy of AT+BFR training in individuals with T2D compared to the standard care AT (AT- stdCare).

Methods: This study is a single-blind (investigator & statistical analyst), multi-site, randomized controlled pilot trial of a novel AT+BFR training intervention for individuals living with T2D, which has been informed by patients with lived experience. Participants will be randomized 1:1 using variable permuted block sizes (stratified by sex and site) into 1) AT+BFR or 2) AT-stdCare groups with outcome measures assessed at baseline and 6 weeks.

Population: In 3 sites across Canada, 60 (n=20 per site) individuals living with T2D (5.7% < HbA1c < 9.0%) aged 19-64 years, not meeting the physical activity guidelines (150 mins moderate-vigorous physical activity per week) will be recruited to participate in this 6-week pilot trial.

Intervention: Participants will perform supervised AT+BFR 3 times weekly for 32 minutes per session. A blood pressure cuff will be set between 60-80% of limb arterial occlusion with AT for 96 minutes per week of treadmill walking performed at 40-50% of heart rate reserve (HRR).

Participants in the AT-stdCare will perform 96 minutes per week of treadmill walking at 40-50% of HRR following the same schedule as AT+BFR, training 3 times per week for 32 minutes per session.

Outcomes: The main outcome measures will pertain to the feasibility of a larger trial and include recruitment rates, enrollment and adherence to the intervention, and retention for follow-up testing. The secondary outcomes will be focused on establishing effect sizes to power a larger trial. Effect sizes for the change in cardiorespiratory fitness and continuous glucose monitoring (CGM) outcomes will be determined to help select and power a primary outcome for a more definitive trial of AT+BFR.

Inclusion criteria

• Diagnosed with type 2 diabetes (5.7% < HbA1c < 9.0%)
• Not regularly physically active (150 mins moderate-vigorous physical activity per week)

Exclusion criteria

• Musculoskeletal issues preventing exercise training
• Unstable medications over the last 3 months
• Absolute contraindications to BFR (i.e. peripheral vascular disease)
• A self-reported diagnosis of low iron concentrations, anemia, or being treated for these conditions
• A diagnosis of any red blood cell-altering condition (i.e., sickle cell anemia, poikilocytosis)
• Currently living with any cardiovascular disease, which would impact the ability to participate in exercise safely
• Currently prescribed any medication which would impact the ability to use a heart rate monitor to accurately track intensity