The corticomuscular response to experimental pain via blood flow occlusion when applied to the ipsilateral and contralateral leg during an isometric force task

Blood flow occlusion (BFO) has been previously used to investigate physiological responses to muscle ischemia, showing increased perceptual effort (RPE) and pain along with impaired neuromuscular performance. However, at present, it is unclear how BFO alters corticomuscular activities when either applied to the exercising or nonexercising musculature. The present study therefore set out to assess the corticomuscular response to these distinct BFO paradigms during an isometric contraction precision task. In a repeated measures design, fifteen participants (age = 27.00 +/- 5.77) completed 15 isometric contractions across three experimental conditions; no occlusion (CNTRL), occlusion of the contralateral (i.e., nonexercising) limb (CON-OCC), and occlusion of the ipsilateral (i.e., exercising) limb (IPS-OCC). Measures of force, electroencephalographic (EEG), and electromyographic (EMG) were recorded during contractions. We observed that IPS-OCC broadly impaired force steadiness, elevated EMG of the vastus lateralis, and heightened RPE and pain. IPSI-OCC also significantly decreased corticomuscular coherence during the early phase of contraction and decreased EEG alpha activity across the sensorimotor and temporoparietal regions during the middle and late phases of contraction compared with CNTRL. By contrast, CON-OCC increased perceived levels of pain (but not RPE) and decreased EEG alpha activity across the prefrontal cortex during the middle and late phases of contraction, with no changes observed for EMG and force steadiness. Together, these findings highlight distinctive psychophysiological responses to experimental pain via BFO showing altered cortical activities (CON-OCC) and altered cortical, corticomuscular, and neuromuscular activities (IPS-OCC) when applied to the lower limbs during an isometric force precision task. Blood flow occlusion is a common experimental model to induce pain and fatigue during exercise. However, the corticomuscular mechanisms underlying this model remain poorly understood. In this study, we show that blood flow occlusion of non-exercising musculature elicits a suppression of electromyographic (EEG) alpha activity across the prefrontal cortex. By contrast, occlusion of exercising musculature elicits a suppression of EEG alpha activity across central and posterior cortical regions and impairs both brain-muscle communication and neuromuscular activation.