Effects Of Running With And Without Blood Flow Restriction On Gas Exchange Kinetics

PURPOSE: Applying blood flow restriction (BFR) can augment aerobic exercise training, but it has not been determined if this response is intensity dependent. The purpose of this investigation was to compare the acute effects of running with and without BFR at different peak running velocities on gas exchange kinetics. METHODS: Ten (21.4 ± 1.3 years, 163 ± 7.1 cm, 57.1 ± 4.9 kg) aerobically trained (VO2 max = 46.3 ± 7.4 ml/kg/min) women completed four, three-minute running bouts interspaced with five minutes of active rest. In a randomized order, participants ran at 70%, 80%, and 90% of peak running velocity with BFR and at 100% of peak running velocity without BFR. Peak running velocity was quantified as the top speed achieved during a customized RAMP protocol which began at 6 miles per hour and increased by 0.1 mile per hour every 12 seconds until failure. Gas exchange kinetics (i.e., oxygen consumption [VO2] and carbon dioxide production [VCO2]) were analyzed every 60 seconds during each bout using a 4 [Condition (70%, 80%, 90%, 100%)] x 3 [Time (every 60 seconds)] repeated measures ANOVA. RESULTS: There were no significant (p = 0.218; p = 0.293) interactions for VO2 and VCO2, but there were significant (p < 0.001-0.028) main effects for Time and Condition. Specifically, VO2 and VCO2 increased from minute one (27.4 ± 5.3 ml/kg/min and 5.9 ± 3.3 L/min) to minutes two (38.1 ± 5.9 ml/kg/min and 8.2 ± 4.4 L/min) and three (38.3 ± 6.2 ml/kg/min and 8.3 ± 4.4 L/min). Further, there were intensity dependent responses for VO2 (70% [30.7 ± 5.9 ml/kg/min] < 80% [33.5 ± 7.2 ml/kg/min] < 90% [35.9 ± 7.8 ml/kg/min] < 100% [38.4 ± 7.9 ml/kg/min]) and for VCO2 (70% [6.6 ± 3.7 L/min] < 80% [7.2 ± 3.9 L/min]) and (90% [7.7 ± 4.2 L/min] <100% [8.3 ± 4.4 L/min]). CONCLUSIONS: Oxygen consumption and carbon dioxide production increased with peak running velocity and plateaued within each three-minute bout. Muscle gas kinetics appear to be robust to the application of BFR and/or BFR was insufficient to compensate for reduction in peak running velocity on subsequent oxygen consumption and carbon dioxide production. The potential benefit of BFR aerobic exercise is likely unrelated to acute muscle gas kinetics but may reside within the local musculature.