The trunk muscles are normally activated during walking to provide upper body steadiness throughout the gait cycle [
9,
10]. Several studies have shown certain patterns of activation for each muscle. In these studies, the abdominal muscles were documented to have variable patterns of activity with most participants exhibiting a low and constant muscle activity throughout the gait cycle. However, some individuals do exhibit rhythmic activation; for instance, RA activity may be rhythmically active with a peak around mid-stance [
18] or end-stance [
19] while EO may peak close to ipsilateral [
19,
20] or contralateral heel strike, especially at higher speeds due to higher postural stability demands [
11]. In the paraspinal muscles, activation patterns reported in the literature seem to be more consistent across individuals, with ES rhythmically active and peaking around heel strike [
19,
21]. The data from our able-bodied control subjects are consistent with these previous reports [
11,
18‐
22]. Among our able-bodied control group, trunk EMG patterning during walking in the Ekso was similar to that observed during normal overground walking, albeit with higher amplitudes. Sylos-Labinin et al. [
23] also observed that able-bodied participants walking with the MINDWALKER research exoskeleton, which has a similar walking mechanism to the Ekso, showed similar or higher trunk muscle activity compared to normal walking. In our SCI subjects, when rhythmic activity was observed, the patterning was qualitatively similar to that reported during normal walking in able-bodied participants [
11,
18‐
22].