## 3 Results
### Muscle Activations When Walking with and without the Ekso  
When walking with the Ekso with respect to NW (Figure 6), the activity of the distal lower limb muscles--TA, GM, SOL--decreased, as well as the activity of the GLM, both with (B-FA) and without (B-NA) assistance. These differences were observable mainly in correspondence of the peak of muscle activations, more specifically between 20-40% of the gait cycle for the SOL (\(p<0.001\)) and for the GM  
Figure 5: First and fourth rows: Muscle activations patterns during walking inside the Ekso with different assistance modalities. Unilateral assistance was indicated with dashed lines, while bilateral assistance was indicated with continuous lines, and the type of assistance was indicated by the color of the lines: B-FA (red), B-AA, U-AA (blue), B-NA, and U-NA (green). We considered the following muscles: muscles tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SOL), rectus femoris (RF), vastus medialis (VM), semientdinosus (ST), biceps femoris (BF), and glutetus medius (GLM). Second and fifth rows: SPM[F] statistic as a function of the percentage of gait cycle. The lines were obtained by averaging the strides performed with crutches and walkers as well as the strides started with the left and right leg. The threshold for significance is indicated in red. Third and sixth rows: Statistic results of the pre-planned comparison: (1) B-FA vs. B-AA, (2) B-AA vs. U-AA, (3) B-NA vs. U-NA, (4) –A vs. -NA. Black intervals \(p<0.001\) and grey intervals \(p<0.05\). (\(p\) = 0.05, i.e., at the threshold of significance), in the second half of the gait cycle for the TA (\(p\) < 0.02 in the B-FA and \(p\) < 0.001 in the B-NA), and between 40-50% for the GLM (\(p\) = 0.007 in the B-FA). This decrease of muscle activity was significant for the TA and the SOL, but not for the other two muscles, and it was more marked in absences of Ekso assistance. Conversely, the RF had higher activations when subjects walked with Ekso at the end (\(>\)80%) of the gait cycle, although this difference increased and was statistically significant only when the Ekso assistance was present (\(p\) = 0.01). We did not observe any significant difference for the VM. Most interestingly, we observed different timings of activation for the ST. When walking with the Ekso, the  
Figure 6: Rows 1, 3, 5, and 7: Comparison between normal walking (black lines) and bilaterally assistive (B-FA) walking with the Ekso (top panel, rows 1–3, red lines) and unassisted (B-NA) walking with the Ekso (low panel, rows 5–7, green lines) (mean \(\pm\) SE). We considered the following muscles: muscles tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SOL), rectus femoris (RF), vastus medialis (VM), semitendinosus (ST), biceps femoris (BF), and gluteus medius (GLM). The lines were obtained by averaging the strides performed with crutches and walkers as well as the strides started with the left and right leg. Rows 2, 4, 6, 8: panels show the SPM[F] statistic as a function of the percentage of gait cycle. The threshold for significance is indicated in red. peak of activation was between 60-80% of the cycle both in the assisted and unassisted modalities, while in this interval during NW, the ST was not active. This difference was highly significant for both B-FA and B-NA (both \(p<0.001\)). A similar trend, although less marked, was observed for the BF, but the difference between Ekso and normal walking in this part of the gait cycle, i.e., from 60% to 80%, did not reach the threshold for significance. Both the BF and the ST muscles were not active at the beginning (<15%) and at the end (>80%) of the gait cycle, which are time intervals where normally, these muscles are active during walking. At the end of the gait cycle, the difference between NW and B-NA/B-FA was in all cases highly significant (\(p<0.001\) for both muscles), while at the beginning of the gait cycle, it was significant for the BF (\(p<0.001\)), and for the ST, it was only slightly significant in the NW versus B-NA case (\(p=0.049\)).