## 4 Discussion  
Based on the results obtained, it can be concluded that the proposed research hypothesis about the significant effect of external leg loading on the intensity of physical exercise in young, healthy, physically fit adults playing AVRG on an omnidirectional treadmill has been confirmed. AWs of 2 kg have proven to be an effective way to increase exercise load during the performance of locomotor movements in VR. Furthermore, it was shown that the use of an omnidirectional treadmill as a device coupled with a VR headset is a promising solution that allows for creating conditions and tools for vigorous training in a virtual environment. Although many recent studies have assessed PA intensity in VR [13; 15; 16; 19; 33; 34], few of them addressed exercise using an omnidirectional treadmill. This is probably due to the fact that this type of equipment is still relatively expensive and not widely available. A study evaluating the intensity of exercise in VR on a treadmill was recently conducted by [PERSON] et al. [35]. The experiment was conducted in a group of eleven children with obesity aged 8 to 12 years. The objective of the study was to evaluate the intensity of PA during 15 min of playing two different AVRGs. The authors also evaluated whether the games' storyline could motivate children to engage in locomotor activity (moving in a confined space vs. having to follow a set route). The intensity of PA in obese children was high for both games, but it was significantly higher during the game in which the players had to follow a set route than during the game whose storyline involved moving in a confined space. The parameters for physical exercise intensity were, therefore, similar to those obtained by the participants in the present study. However, it should be noted that obese children and AWF students with above-average fitness differ in their exercise capacity. According to the authors, AVRGs practiced on a treadmill regularly by overweight children may be a health-promoting form of PA for them. Similar studies using a multidirectional treadmill were also conducted by [PERSON] et al. [13]. One of several aspects of their study was a comparison of PA intensity during 10 min sessions of physical exercise using AVRGs and two innovative training devices (an omnidirectional treadmill and the Icaros Pro flight simulator). The authors studied eleven young men. The mean exercise intensity during training on the omnidirectional treadmill was at a high level and was higher than while training on the flight simulator. According to the authors, their preliminary research indicated that these trainers, coupled with AVRGs, offer an effective tool for increasing participation in health-related PA.  
To date, there have been no studies on PA with AWs in VR. Therefore, our results can be only related to papers on exercises in RL that have assessed the effects of the external loading of the lower limbs on PA intensity. [PERSON] et al. [36] evaluated the effects of ankle and wrist loading on physiological responses while running on a treadmill. The authors used weights of 1.6, 3.2, and 4.8 kg. The magnitudes of these responses were significantly higher with the weights at the ankles than at the wrists. The participants' perceived exertion also increased under the additional load. According to the authors, since AWs increase energy expenditure and training intensity during treadmill running, they are likely to result in greater increases in cardiovascular fitness and greater weight loss than during training without the weights. According to [PERSON] and [PERSON] [37], applying additional load during walking can make its intensity similar to that of faster running. Furthermore, [PERSON] et al. [38] studied the effects of different gait speeds and ankle joint loads on metabolic and neuromuscular responses of the lower limbs during gait. Their findings suggest that the effect of ankle loading on exercise intensity and neuromuscular responses is higher for higher gait speeds. Benefits can also come from the long-term use of AWs.