Low-intensity knee extension exercise with blood-flow restriction at 60% and 80% of arterial occlusion pressure significantly increased muscle deoxygenation compared to unrestricted exercise (p < 0.05).
RCT (n=13)
Open-label
Randomized crossover order
No
Do different levels of blood flow restriction during low-intensity exercise reduce muscle microvascular oxygenation in active young men?
During low-intensity exercise, a relative pressure above 40% of resting arterial occlusion pressure is required to significantly alter microvascular oxygenation compared to unrestricted exercise.
Tasa de eventos absoluta: 27.3% vs 19.5%
valor p: p=<0.05
Blood flow restrictive (BFR) exercise elicits a localized hypoxic environment compatible with greater metabolic stress. We intended to compare the acute changes in muscle microvascular oxygenation following low-intensity knee extension exercise, combined with different levels of BFR. Thirteen active young men (age: 23.8 ± 5.4 years) were tested for unilateral knee extension exercise (30+15+15+15 reps at 20% one repetition maximum) on 4 different conditions: no-BFR (NOBFR), 40, 60 and 80% of arterial occlusion pressure (AOP). Deoxyhaemoglobin+myoglobin concentration DeoxyHb+Mb, total haemoglobin T(H+Mb) and tissue oxygen saturation TOI were measured on the vastus lateralis muscle using near-infrared spectroscopy (NIMO, Nirox srl, Brescia, Italy). The magnitude of change in DeoxyHb+Mbduring exercise was similar between 60 and 80% AOP. Overall, compared to that seen during 60 and 80% AOP, NOBFR as well as 40%AOP resulted in a lower magnitude of change in DeoxyHb+Mb (p < 0.05). While the oxygen extraction decreased during each inter-set resting interval in NOBFR and 40%AOP, this was not the case for 60 or 80%AOP. Additionally, TOI values obtained during recovery from each set of exercise were similarly affected by all conditions. Finally, our data also show that, when performed at higher restrictive values (60 and 80%), BFR exercise increases total DeoxyHb+Mbextraction (p < 0.05). Taken together, we provide evidence that BFR is effective for increasing deoxygenation and reducing tissue oxygenation during low-intensity exercise. We also showed that when using low loads, a relative pressure above 40% of the arterial occlusion pressure at rest is required to elicit changes in microvascular oxygenation compared with the same exercise with unrestricted conditions.
Reis et al. (Thu,) conducted a rct in Healthy (n=13). Blood-flow restricted (BFR) exercise vs. Unrestricted exercise (NOBFR) was evaluated on Change in deoxygenated hemoglobin+myoglobin (Deoxy[Hb+Mb]) during Set 4 of exercise (p=<0.05). Low-intensity knee extension exercise with blood-flow restriction at 60% and 80% of arterial occlusion pressure significantly increased muscle deoxygenation compared to unrestricted exercise (p < 0.05).