## 4 Discussion
[23] found reductions in time of 2.1 s in the TUG test after the performance of three 40 min sessions of forced cycling at 75-85 rpm and at 50-80% of the reserve heart rate. In our case, we obtained in the group that used IVR an average reduction of 3.92 s, a difference greater than 3.5 s, which is considered the minimum clinically important difference in cases of PD [68]. For its part, the pedaling group without IVR, although there was post-intervention improvement in the dual-task TUG test, did not reach the minimum clinically important difference, as in the study by [PERSON] et al. [23]. In relation to gait improvements, this study's results are in line with the findings of previous research. After one 40 min session of forced cycling at 80 rpm and at 60-70% of the reserve heart rate, [PERSON] et al. [21] observed an improvement in the hip's range of motion. Gait improvement was also seen in other research, both in studies of only a few sessions [24] and in interventions of several weeks [22; 25]. We also found significant improvements in motor function and a reduction in PD symptomatology when these were assessed with the MDS-UPDRS, both in Part III (motor assessment) and Part IV (motor complications). These findings are also in line with those of previous studies, including not only those using the timed motor test battery [22] but also those using the MDS-UPDRS [13; 18; 20; 23; 24; 27] or functional MRI [13; 20]. However, although [PERSON] et al. [25] observed improvements in subjects' gaits and tremor reduction (measured with a Kinesia device containing accelerometers and gyroscopes), they did not achieve significant improvements in the MDS-UPDRS (Part III). Thus, the group that performed pedaling with IVR showed improvements of 6.38 points in subscale III and 6.75 points in the total score, which represent a moderate and minimal clinically important difference, respectively [69]. There was also a minimal clinically important difference in parts IB and II, reaching more than 2.64 points and 3.05 points, respectively [70]. These clinically relevant scores for patients were also observed in the CG (Part IV and total score of the MDS-UPDRS), showing the benefits that high-intensity aerobic exercise had in the sample using a smart cycloergometer and improving the motor function and the symptoms generated by PD. Likewise, quality of life was assessed in our study via the PDQ-39 scale. After the intervention, the SG achieved significant improvements when compared with the CG in the domains of stigma, cognition, physical discomfort, and total score. These findings contrast with those of [PERSON] et al. [8], who after the study group carried out a cardiovascular exercise program at 60-85% of the maximum heart rate (stationary bike, rowing, or treadmill) and strength for 12 weeks (2 sessions/week) found no significant improvements in the quality of life of the PD patients. This may have been due to a lower cardiovascular exercise intensity requirement than that which was utilized in our study. This could be an aspect to keep in mind during future research. Finally, the results of the specific variables related to IVR show that its application is safe and tolerable. Although IVR and cybersickness are sometimes linked in the literature, in the present study, the adverse symptomatology related to virtual exposure was residual, being in line with other studies that used IVR for PD [51; 71; 72], and in our case, the number of sessions was significantly higher than those of the comparative studies. Even so, this possibility should never be ruled out, since virtual scenarios with movement or accelerations and the variability of each participant can trigger cybersickness more easily. The usability of the equipment was also high (>82%). Even though they were older people, which could lead to some reluctance to use new technologies, the EG felt comfortable with the intervention carried out.