Cerebral cortical activation and muscle performance during blood flow restriction training after ischemic stroke: A randomised functional near-infrared spectroscopy study.

Abstract

To compare the effects of low-load (LL) blood flow restriction (BFR) and high-load (HL) training on cortical activation and the specific contributions of individual brain regions to functional recovery in stroke patients. Sixty-six patients with ischemic stroke were divided into BFR (30% one-repetition maximum [1RM]), matched LL, or HL (80% 1RM) groups. Patients underwent a four-week supervised cycling program, and oxyhemoglobin (HbO) concentrations were assessed during the first session and after the program via functional near-infrared spectroscopy (fNIRS). Muscle performance was characterized by the rectus femoris muscle cross-sectional area (CSA), knee extensor peak torque (PT), and Fugl-Meyer lower extremity (FMLE) scores. Compared with the LL group, the BFR and HL groups presented significant brain activation (increased HbO concentration) during the first session (P < 0.05). Following the 4-week intervention, the BFR and HL groups presented greater changes in the HbO concentration (ΔHbO), PT and FMLE scores than did the LL group (P < 0.05). The ΔHbO values in the primary motor cortex (M1), premotor cortex and supplementary motor area (PMC-SMA) of the affected hemisphere (AH) were considerably greater than those in the unaffected hemisphere (P < 0.05), whereas there was no difference in the dorsolateral prefrontal cortex (DLPFC). Changes in PT (mean r = 0.51 [range = 0.46-0.55]; P < 0.05) and FMLE scores (mean r = 0.54 [range = 0.48-0.62]; P < 0.05) were positively correlated with the AH M1 and PMC-SMA ΔHbO across groups. By actively manipulating the M1 and PMC-SMA, LL-BFR and HL training yield comparable short-term improvements in central and peripheral performance after stroke. (Registry: Chinese Clinical Trial Registry; ChiCTR2400087378).