Physiological Responses To Intermittent Blood Flow Restriction During Cycling Exercise

Abstract

Aerobic exercise with the addition of blood flow restriction (BFR) has the potential to elicit physiological adaptations. However, the acute physiological and perceptual responses during aerobic exercise with intermittent BFR remains unclear. PURPOSE: The purpose of this investigation was to examine the physiological and perceptual responses to intermittent BFR compared to low- (LIIE) and high-intensity interval exercise (HIIE). METHODS: Participants randomly performed 3 interval (INT) exercise protocols: BFR, LIIE and HIIE. BFR and LIIE consisted of 10 INTs of 2-min of work at 70% of ventilatory threshold (VT) and 1-min of recovery (20 W). During BFR, the cuffs were inflated to 80% of limb occlusion pressure (154 ± 17 mmHg) during each work INT and deflated during recovery INTs. HIIE consisted of 5 INTs at 140% of VT and 1-min of recovery (20 W). Pulmonary VO2 and respiratory exchange ratio (RER) were recorded and tissue oxygen saturation (StO2) was assessed by near-infrared spectroscopy. The level of perceived exertion (RPE) was assessed at the end of each INT. INTs 2, 4, 6, 8, and 10 during BFR and LIIE were used for comparison with INTs 1-5 during HIIE. The last 30 seconds of each INT were used for analysis. StO2 during each condition is expressed as change from baseline cycling (20W) (arbitrary units; AU). Two-way (INT x trial) ANOVAs analyzed differences. Significance was established if p<0.05. RESULTS: There was a main effect of trial for VO2 and RER. VO2 was greater in HIIE (INT 5 = 2.12 ± 0.56 L*min-1) than BFR (INT 10 = 1.41 ± 0.21 L*min-1) and LIIE (INT 10 = 1.28 ± 0.27 L*min-1). RER was lower in LIIE (INT 10 = 0.93 ± 0.01) compared to BFR (INT 10 = 0.94 ± 0.06) and HIIE (INT 5 = 0.99 ± 0.03). At all points, HR was lower in LIIE (INT 10 = 110 ± 10 bpm) than BFR (INT 10 = 155 ± 24 bpm) and HIIE (INT 5 = 154 ± 14 bpm). There were no differences in HR between BFR and HIIE. Delta StO2 was greater during BFR (INT 10 = -37.5 ± 15.6 AU) and HIIE (INT 5 = -34.2 ± 6.5 AU) compared to LIIE (INT 10 = -14.6 ± 8.67 AU). During all points, RPE was greater in BFR (INT 10 = 15.0 ± 2.4) and HIIE (INT 5 = 14.3 ± 1.3) compared to LIIE (INT 10 = 9.3 ± 0.4). CONCLUSIONS: This study suggests that cycling with the addition of intermittent BFR at an intensity equivalent to 70% of VT may provide similar cardiovascular and local physiological stress to traditional HIIE, albeit at a lower work rate.