Effect of blood flow occlusion on neuromuscular fatigue following sustained maximal isometric contraction

Sustained isometric maximal voluntary contractions (IMVCs) have blood flow occlusive effects on the microvasculature. However, it is unknown if this effect would be magnified with additional blood flow restriction via a cuff and what the influence on fatigue development would be. Twelve healthy male participants performed a 1-min IMVC of the knee extensors with and without additional blood flow occlusion induced by pneumatic cuff in counterbalanced order on separate days. Vastus lateralis muscle deoxygenation was estimated via near-infrared spectroscopy-derived tissue oxygen saturation (SmO₂) throughout the fatiguing contraction. Central and peripheral measures of neuromuscular fatigue (NMF) were assessed via surface electromyography (EMG) and force responses to voluntary contractions and peripheral nerve/transcranial magnetic stimulations before, immediately after, and throughout an 8-min recovery period. SmO₂, force, and EMG amplitude decreased during the 1-min IMVC, but there were no between-condition differences. Similarly, no significant (p > 0.05) between-condition differences were detected for any dependent variable immediately after the fatiguing contraction. Transcranial magnetic stimulation (TMS)-derived voluntary activation was lower (p < 0.05) in the no-cuff condition during the recovery period. Sustained IMVC results in a similar degree of muscle deoxygenation and NMF as IMVCs with additional occlusion, providing further evidence that a sustained IMVC induces full ischemia. Novelty NMF etiology, muscle oxygenation, and corticospinal factors during an IMVC are similar with or without an occlusion cuff. Contrary to all other measures, TMS-evaluated voluntary activation returned to baseline faster following the occluded condition.