## 3 Results  
The sequence of bioelectrical activity of muscles in response to a visual stimulus was determined with the use of EMG. It was demonstrated that fencers in Group A activated first the muscles of the back (LD RT and LD LT) and then the deltoid muscle (DEL RT), the external abdominal oblique muscle (EAO RT), the forearm muscles (ECR RT), and the triceps brachii extensor (TRI RT). At the end of the thrust phase, the flexors (BC RT and FCR RT) were activated.  
In fencers from Group B, it was the forearm muscles (ECR RT), abdominal muscles (EDA LT and RT), and muscles of the back (LD LT and RT) that were activated first, followed by the upper limb muscles (BC RT, DEL RT, and TRI RT). At the end of the thrust the flexor carpi radialis muscles (FCR RT) were activated.  
The results of a non-parametric test for two independent samples (Wald-Wolfowitz Runs Test) confirmed the above analysis. The shortest activation time was recorded for the LDLT (Group A--0.333 ms; Group B--0.522 ms; \(p\) = 0.039). However, in intergroup comparisons, with respect to the EMG signal expressed as % of MVC, there were higher MVC values in most of the examined muscles. In this case, the highest statistical significance value was observed for the DELRT (114.63) in category A fencers, and 65.50 in category B fencers (\(p\) = 0.039). This proves the key significance of the back and upper limb muscles in the structure of offensive actions in wheelchair fencing.  
A detailed wavelet coherence analysis revealed intermuscular synchronization at 8-20 Hz in Group A fencers and at 5-15 Hz in Group B fencers. It is significant that coherence increases after the cessation of the most intense activity (offensive action), up to several ms in the range of 60-100 Hz. In addition, previous studies have shown that individuals with high degrees of spinal cord injury displayed higher EMG activity of the trunk muscles while sitting compared to individuals with low degrees of injury. The results of this study revealed that in Paralympic wheelchair fencers, muscle activation occurred at low frequency levels, regardless of disability category. Moreover, significantly higher coherence indices were noted in category B fencers, at different frequency levels. This may indicate that individuals with more severe neurological deficits (disability category B) require greater stabilization of trunk muscles in order to maintain stable posture and skillfully execute difficult technical tasks.  
EMG signals were recorded at a sampling rate of 10 KHz. Three frequency bands (2-16, 17-30, and 31-60 Hz) were selected for analysis, and all coherence scores in each specific band from each fencer were averaged to obtain a high average coherence for a given frequency band.  
The investigation of muscle co-activation showed that wheelchair fencers displayed a diverse pattern of muscle co-activation indices expressed as a percentage. Considering the actions on the visual stimulus (thrust to the torso in response to the coach's movement), the fencers in Group A demonstrated higher co-activation in the right-side back and abdominal muscles (50.94) and the upper limb muscle pairs ECR-FCR (50.75), TRI-BC (47.99). In contrast, fencers in Group B reported higher values only for the left-side postural muscle pairs (50.54).