Spinal cord injury (SCI) affects an estimated 250,000 to 500,000 people globally each year according to the World Health Organization (WHO). It often results in neuromuscular deterioration below the injury site, leading to changes in motoneuronal behaviour and spastic responses. These changes impact intrinsic ionic currents, notably the persistent inward currents (PICs), which are crucial for motoneuronal excitability and motor output. This study explores the PICs in individuals with SCI by analysing pre-recorded high-density surface electromyography (HDsEMG) signals from the tibialis anterior (TA), gastrocnemius medialis (GM) and soleus (SOL) muscles. These signals were obtained from a prior study, performed on an SCI group and an able-bodied control group, and involved trapezoidal contraction trials at 20 % and 50 % maximal voluntary isometric contraction (MVIC). PIC estimations were conducted using the paired motor unit (PMU) analysis to quantify frequency differences (∆f) between a higher threshold test unit and a lower threshold control unit, which reflect PIC amplitude. Several criteria were established to ensure that test-control unit pairs shared common synaptic input, a fundamental premise of PMU analysis. The analysisrevealed deficiencies in available motor units (MUs) for reliable PIC estimations, particularly in the GM at 20 % MVIC of the SCI group. Despite methodological effectiveness in the control group, PIC amplitudes were reduced in the TA and SOL muscles of the SCI group compared to the control group. Future research could include a younger SCI cohort, as the participants in this study were older than those typically observed in other studies. Similarly, expanding PIC research efforts towards older adults is warranted, as there is a gap in validation data in current research for PICs in lower limb muscles in this demographic. Additionally, incorporating multiple measurement sessions could mitigate the influence of spastic events on data acquisition, particularly for muscles like the GM in this study where the data was less reliable.