Supplementary Figures for (Asp et. al., 2026, J. Neurophysiology)

Supplemental Figure S1. Recruitment curves for first pulse response (R1) across lower extremity muscles. Peak-to-peak EMG amplitude of the first evoked response (R1) as a function of stimulation amplitude for epidural stimulation (ES, black) and dorsal root ganglion stimulation (DRGS, red) across six lower extremity muscles. Thin lines represent individual participant responses (n=19), thick lines represent mean responses, and shaded regions represent 95% confidence intervals.Supplemental Figure S2. Recruitment curves for second pulse response (R2) across lower extremity muscles. Peak-to-peak EMG amplitude of the second evoked response (R2) following paired-pulse stimulation (50 ms interpulse interval) as a function of stimulation amplitude for epidural stimulation (ES, black) and dorsal root ganglion stimulation (DRGS, red) across six lower extremity muscles. Thin lines represent individual participant responses (n=19), thick lines represent mean responses, and shaded regions represent 95% confidence intervals. Supplemental Figure S3. Threshold stimulation amplitudes by muscle for ES and DRGS. Box plots showing the distribution of motor threshold amplitudes (mA) required to evoke EMG responses across six leg muscles for epidural stimulation (ES, black) and dorsal root stimulation (DRGS, red). Boxes represent the interquartile range (25th to 75th percentile), horizontal lines within boxes indicate median values, whiskers extend to 1.5× the interquartile range, and individual points represent outliers. ES demonstrated higher threshold amplitudes for proximal muscles (RF, VL, MH) relative to distal muscles (TA, MG, SOL). In contrast, DRGRS showed relatively lower and more consistent threshold amplitudes for proximal muscles, with higher amplitudes required to activate distal muscles. Data aggregated across n=19 participants. Abbreviations: RF, rectus femoris; VL, vastus lateralis; MH, medial hamstring; TA, tibialis anterior; MG, medial gastrocnemius; SOL, soleus.