Blood flow restriction during knee extension resulted in higher deoxyhemoglobin concentrations (57.8 vs 35.0 μM; P<0.0001) and lower O2 saturation during recovery compared to matched exercise.
Does blood flow restriction alter tissue oxygenation during knee extension in young healthy males?
Blood flow restriction during knee extension significantly alters local muscle and prefrontal cortex oxygenation kinetics, providing insight into its physiological mechanisms.
Absolute Event Rate: 57.8% vs 35%
p-value: p=< 0.0001
Purpose Time-resolved near-infrared spectroscopy was used to quantify tissue oxy- and deoxyhemoglobin concentrations (HbO2 and HbR) and O2 saturation (stO2) in the oblique fibers of the vastus medialis muscle and brain prefrontal cortex during knee extension with and without blood flow restriction (BFR). Methods Six young healthy males performed three sets of knee extensions on a dynamometer (50% one-repetition maximum) separated by 90-s rest periods in three conditions: 1) until fatigue without BFR (fatigue), 2) until fatigue with BFR (100 mm Hg cuff constriction around thigh (BFR)), 3) same number of repetitions from condition 2 without BFR (matched). Each condition was performed on a separate visit. Results BFR was associated with higher HbR at the oblique fibers of the vastus medialis muscle (rest 1: 57.8 (BFR) vs 35.0 μM (matched); P < 0.0001) and a significantly lower stO2 during recovery periods between sets (7.5%–11.2 % lower than non-BFR conditions for rest 1 and 2, P < 0.0001). Using a piecewise linear spline method, a spike in HbR was observed before the onset of HbR clearance during recovery, causing HbR clearance to begin at a higher concentration (81 (BFR) vs 62 μM (matched), P = 0.029). HbO2 kinetics during recovery were also affected by BFR, with longer duration (BFR, 51 s; matched, 31 s; P = 0.047) but lower rate of increase (BFR, 58 μM·min−1; matched, 89 μM·min−1; P = 0.004) during recovery. In the prefrontal cortex, BFR was associated with increased HbR, diminished increase in HbO2, and higher subjective exertion. Conclusions These findings yield insight into possible physiological mechanisms of BFR and suggest a role of time-resolved near-infrared spectroscopy in monitoring and optimization of BFR exercise on an individual basis.
Ganesan et al. (Wed,) conducted a other in Healthy (n=6). Blood flow restriction (BFR) vs. Without BFR (fatigue and matched repetitions) was evaluated on Deoxyhemoglobin concentration ([HbR]) at the oblique fibers of the vastus medialis muscle during rest 1 (p=< 0.0001). Blood flow restriction during knee extension resulted in higher deoxyhemoglobin concentrations (57.8 vs 35.0 μM; P<0.0001) and lower O2 saturation during recovery compared to matched exercise.