## 3 Results
### Muscle Activations When Walking with the Ekso under Different Conditions  
As expected, there were no differences (neither main effects nor interactions) in muscle activations between left and right leg during the gait cycle. Moreover, the muscle patterns did not change when walking with the crutches or with the walker, i.e., no significant main effects nor interactions were found for the factor aids (\(p>0.05\), Figure 4).  
When comparing the different assistance modalities (Figure 5), we found that the temporal patterns of activations did not change with the different assistive modalities, i.e., for all the muscles, the shape of the envelopes were highly similar; however, significant differences were observed in terms of level of muscle activations.  
Specifically, small or negligible differences were found for the distal lower limb muscles (TA, GM, SOL), while higher and significant differences were found in the other muscles (GLM, BF, ST, RF, VM). When further investigating this result with the pre-planned comparisons, we found that:  
1. There was no difference between the muscle patterns between the B-FA, with the Ekso providing a fixed maximum assistance, independently of the subjects' voluntary contribution, with respect to B-AA with the assistance adapted by the device, depending on the subject's performance.
2. In the second half of the gait cycle, the level of activations of both the unassisted modalities, B-NA, U-NA, was lower than those of the assistive modalities for the BF, ST RF, VM, and GLM muscles between 60-80% of the gait cycle for the first two muscles (in correspondence with the  
Figure 4: First and third rows: Muscle activation patterns (Mean \(\pm\) SE) during walking inside the Ekso with the walker (blue lines) and crutches (orange lines). 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 all the modalities of walking with the Ekso (B-FA, B-AA, U-AA, B-NA, and U-NA) and the contribution of both legs that were balanced with respect the two aids. Second and fourth rows: Statistical parametric mapping (SPM[F]) statistic as a function of the percentage of gait cycle. The threshold for significance is indicated in red.  
peak of muscle activation, both \(p<0.001\)) and between 80-100% for the other three (RF and VM \(p<0.001\); GLM \(p<0.05\)).
3. Under unilateral assistance, both the assisted (U-AA) and unassisted (U-NA) leg had significant differences when compared to the corresponding case where the contralateral leg was in the same assistive condition i.e., B-AA and B-NA, respectively. These differences were mainly evident and significant in the middle of the walking cycle (40-50%) for the GLM muscle in both comparisons (\(p<0.001\)) for BF when comparing the unassisted conditions B-NA versus U-NA (\(p<0.001\)) and for the ST when comparing the assistive conditions B-AA versus U-AA (\(p<0.001\)). Specifically for the unassisted modalities, the activation was mainly higher for the unilateral condition, while it was lower for the assistive modalities.