Central Neural Adaptative Response Induced by Blood Flow Restriction with Low-load Resistance TrainingEvidence from an fNIRS Study

Objective In order to verify the neural adaptation triggered by blood flow restriction training (BFRT) with low-load resistance training and explore the neural mechanisms, this study monitored the blood oxygen activity in the cerebral cortex via fNIRS under different compression pressures during BFRT.

Methods Twenty-four males participated in a 4 (compression pressure: 0 mmHg, 150 mmHg, 250 mmHg, 350 mmHg)×3 regions of interest: primary motor cortex (M1), premotor cortex-supplementary motor area (PMC-SMA), dorsolateral prefrontal cortex (DLPFC) within-subject design. Changes in cerebral cortex oxygenated hemoglobin concentration (HbO) during 30% 1RM squats with BFRT were measured, and subjective fatigue rating scale and heart rate monitor were used to evaluate internal exercise load.

Results ① HbO were higher during 150 mmHg and 250 mmHg compared to 0 mmHg, but a significant decrease in HbO was observed during 350 mmHg. ② The interaction between compression pressure and regions of interest showed the regulation of cortical HbO by compression pressure was more pronounced in M1 and PMC-SMA. ③ The average heart rate under BFRT was higher than non-BFRT, but no significant difference in average heart rate under different compression pressures. ④ The interaction between compression pressure and evaluation stage (pre- and post-training) showed the rating of perceived exertion (RPE) increased with higher compression pressures only post-training. ⑤ There was a negative correlation between squat 1RM and HbO during BFRT, and the correlation was more pronounced in M1 and PMC-SMA. ⑥ Squat 1RM and neural benefit obtained at 250 mmHg showed no correlation.

Conclusion BFRT can trigger adaptive responses in the central nervous system, and moderate compression pressure achieve the optimal neural benefits in terms of cortical activation. M1and PMC-SMA play important roles in regulation during BFRT. For people with resistance training experience, individuals with different maximum strength can obtain equal neural benefits from BFRT.