Energy Expenditure and Substrate Utilization with Intermittent Blood Flow Restriction Aerobic Exercise

Blood flow restriction (BFR) training is characterized by the use of compressive occlusive devices proximal to the active muscle during exercise. We hypothesized that an acute bout of aerobic BFR exercise would result in equivalent caloric expenditure and substrate utilization when compared with conventional aerobic exercise (CE). Six human volunteers (3M/3F; age, 30.2±2.6 years; BMI, 23.9± 1.0 kg/m2) performed 40-min of treadmill exercise at 65-70% of maximal heart rate (HR) with and without intermittent BFR (220 mmHg thigh cuff pressure applied over 4x5-min intervals followed by 5-min reperfusion periods). HR and metabolic parameters were measured and analyzed in 5-min time blocks. Oxygen consumption (VO2) and CO2 production (VCO2) were used to calculate caloric expenditure between conditions, and the respiratory exchange ratio (RER) was used as an index of substrate utilization. Treadmill speed remained constant at 2.5 mph, while treadmill incline (%) was modified to elicit the target HR response. Treadmill incline was subsequently assessed to determine the absolute intensity of the exercise bouts. VO2 and VCO2 increased at the onset of exercise in both conditions (p2 and VCO2 versus the BFR condition for minutes 10-40 of the exercise bout (p≤0.05 for VO2, p≤0.09 for VCO2). Additionally, a lower treadmill incline (%) was required to elicit the target HR response for BFR exercise compared to CE from minutes 10-40 (Range: 4.0-5.0 % for BFR vs. 5.5-6.8% for CE, p≤0.025). There was no difference in overall caloric expenditure (230.3±22.8 kcal for CE vs. 204.3±22.5 kcal for BFR, P=0.44) or RER (0.87±0.01 for CE vs. 0.88±0.01 for BFR, P=0.55) between conditions. These findings suggest that aerobic exercise with intermittent BFR results in similar caloric expenditure and fuel utilization as CE. Aerobic exercise with BFR could be used as an alternative exercise modality for individuals who cannot exercise at the same absolute workloads as healthy individuals, such as those with musculoskeletal limitations.