## 4 Discussion
According to [PERSON] et al. [39], 3-month lower-limb weighted walking affected local neuromuscular control of the rectus femoris muscle in older adults. [PERSON] et al. [40] indicated that 6-week training with AWs can favorably alter the walking patterns of young, healthy individuals. A study by [PERSON] et al. [41] demonstrated that regular use of AWs contributes to improvements in certain anthropometric parameters (waist circumference, waist-to-hip ratio) and body composition (body fat percentage, skeletal muscle percentage), which, according to the authors, can potentially reduce the risk of cardiovascular disease. The efficacy of AWs in increasing PA intensity found in the abovementioned studies and other benefits associated with the use of additional lower limb loading during locomotion in RL point to the need for similar research in VR, especially since virtual treadmills and applications that stimulate lower limb activity in a virtual environment are likely to be increasingly used. However, there are studies on the use of external arm loading in the form of handheld weights (HHWs) to increase the intensity of PA in an immersive virtual environment [23]. The authors studied young adults playing an AVRG game called Beat Saber without and with HHWs. The study showed that small weights (0.5 kg) caused a statistically significant increase in exercise load during the abovementioned game based mainly on arm movements (cutting virtual objects with lightsabers). The low intensity of PA while playing the AVRG studied increased to a moderate level. According to the authors, the use of HHWs while playing AVRGs based mainly on upper limb movements appears to be an effective and simple way to increase PA intensity, and, according to users, it does not cause discomfort while using the game. It is worth mentioning that new-to-the-market accessories for VR headsets are special disk-shaped overlays for the Oculus 2 controllers, which, when attached to the controllers, allow adjustment of their weight to increase the intensity of the exercise while using the application. Therefore, it turns out that manufacturers consider the extra weight on upper limbs as a method to improve the effectiveness of exercise in VR. Perhaps, in the near future, consumer leg weights dedicated to PA in VR will also be developed. In view of the fact that both upper and lower limb loading can be an effective way to increase the physical exercise of AVRG users, it would be worthwhile to conduct a study on the simultaneous effects of arm and leg loading on PA intensity in a virtual environment. Another aspect of our study was that the students made subjective ratings of perceived exertion on the Borg 6-20 scale. It was found that playing with AWs was perceived as significantly more intense than playing without AWs. Relating the obtained values to the classification of physical activity intensity [32], the respondents perceived both types of exercise as vigorous. Therefore, the objective results obtained using an HR monitor coincided with the subjective assessment of the participants. This may indicate that users engaged in physical exercise in a virtual environment can accurately estimate their own effort. This suggestion is supported by the relatively high significant correlation of the results of objective and subjective measures of exercise intensity for both PA in VR with and without AWs. Our research shows that PA in an immersive virtual environment on an omnidirectional treadmill is attractive to users. Using the PACES questionnaire (with a scale of 1 to 7 points), the respondents rated satisfaction with AVRG highly, both without (6.15 \(\pm\) 0.81) and with ankle weights (6.04 \(\pm\) 0.64). The finding of no statistically significant difference between the ratings indicates that the additional resistance did not bother the players and did not cause discomfort that could affect satisfaction with the exercise.