Observing changes in motoneuron characteristics following distorted sensorimotor input via blood flow restriction

Disruption of the blood supply to a limb in conjunction with active movement boosts muscle growth, aids in rehabilitation, andallows controlled exploration of the sensorimotor system. Yet, the underlying neuromechanical changes have not been observedin great detail. This study aims to report the acute neuromuscular effects of temporary blood flow restriction (BFR) through be-havioral changes at the level of motor units (MUs) using high-density surface electromyography on the abductor digiti minimimuscle during 20 trapezoidal and sinusoidal isometric force tracking tasks (5 pre-BFR, 5 during BFR, and 10 post-BFR).Unsurprisingly, during BFR, reported discomfort levels increased significantly (r < 0.001) regardless of the task ( þ 239% trape-zoidal, þ 228% sinusoidal). However, BFR had very little impact on task tracking performance, though the reconstructed forcederived from the underlying neural drive (smoothed cumulative spike train of MUs) deviated substantially during BFR ( 40% intrapezoidal, 47% in sinusoidal). Regardless of the condition, the numbers of extracted MUs were consistent (20–26 in trapezoi-dal, 23–29 in sinusoidal). Interestingly, the interspike interval (ISI) of these units increased by 28% in trapezoidal and 24% in sinu-soidal tasks during BFR, with ISI steadily returning to original values post-BFR. These results indicate that acute BFR transientlyalters the active MU pool, and MU firing behavior, yet only slightly affects the resulting task performance. However, pre-BFRmotor function is gradually restored after BFR release. These findings provide insights into the resulting effects of acute BFRadministration and the complex response it elicits from the sensorimotor system.