Effect of Blood Flow Restriction on Recruitment Threshold and Amplitude- Frequency Characteristics of Motor Units During Exercise

Low-intensity exercise with blood flow restriction (LI BFR) has been shown to release substances that play a key role in neuroplasticity and may be effective in improving rehabilitation outcomes in patients with neurodegenerative diseases. Researchers suggest that LI BFR engages high-threshold motor units even during low-intensity exercise, leading to increased motor unit end-state variability and a rapid onset of neuromuscular fatigue. However, the amplitude-frequency characteristics and motor unit recruitment strategies during LI BFR are not well understood. The aim of this study was to investigate the effects of blood flow restriction on motor unit activation patterns during low-intensity exercise to elucidate the physiological mechanisms underlying this novel training approach. Participants with a mean age of 33 years were subjected to blood flow restriction during isometric wrist flexion. High-density surface EMG (HD sEMG) activity was recorded from both the flexor carpi radialis and palmaris longus muscles. The study shows that blood flow restriction significantly shifted motor unit activation to high threshold motor units. These findings highlight the need to investigate the long-term effects of LI BFR on motor unit coordination in clinical populations.