## 3 Results
### Evidence from the Literature on the Health Implications of Occupational Exoskeletons  
The aspects of health addressed in the literature on occupational exoskeletons are diverse. Hence, this section reports those that have been observed most frequently in the recent literature. Figure 5A shows the number of studies that reported health improvements, health deterioration or no variation in the health conditions, in case of active, passive or hybrid exoskeletons. As for active exoskeletons, in most cases, it was observed an improvement in health, in line with the general trend (Figure 5A). Many active exoskeletons allow a reduction of loads on the body part they assist, without transferring the weight to other parts such as joints, as they have actuators that provide energy and contribute to lifting loads. This has been demonstrated both by user perceptions and electromyography, which have shown a decrease in muscular usage [6; 23; 24]. Another important aspect of active exoskeletons is the reduction of energy consumed by the user during work activities, which allows a decrease in both effective effort, as demonstrated by the decrease in metabolic consumption, and perceived effort [25]. Finally, active exoskeletons allow the attenuation of intense and repeated stresses on joints to prevent trantionopathies [26]. The negative effects on health from active exoskeletons are few, with the most important one not referring to a particular case but applicable to many application fields, which is the transfer of loads from the shoulder to the waist. In these cases, there is no reduction in loads as expected, while it was reported a decrease in agonist muscles and an increase in antagonist muscles in the case of the shoulder [27; 28]. Recent studies show that passive exoskeletons can support the body part for which they were designed without putting too much strain on other body parts [29; 30]. In contrast to active exoskeletons, load redistribution can be less efficient since there are no energy-providing components, thus it must be discharged someplace, although in many circumstances, this can be done without overloading other body sections. Passive exoskeletons are therefore preferable when there is a need to transport low loads. Thanks to passive exoskeletons, the load can be redistributed during movements, avoiding load peaks that can damage  
Figure 5: Studies that reported health improvements, health deterioration or no variation in the health conditions, in case of active, passive or hybrid exoskeletons (**A**); prototypes and commercial exoskeletons (**B**); studies that reported health improvements, health deterioration or no variation in the health conditions, in case of exoskeletons supporting different body areas (**C**). muscles, causing, for example, tears or contractions [31; 32; 33; 34; 35]. Another positive aspect of these exoskeletons is the decrease in metabolic consumption during lifting. Some studies reported a slight increase during walking, but this has no effect on the ultimate result, allowing the user to be less fatigued [36]. Passive exoskeletons, like active exoskeletons, can reduce acute and repetitive pressures on arm muscles to avoid tendinopathies [26]. Finally, passive exoskeletons allow greater movement stability, improving the user's balance and comfort [37]. Negative aspects on health are instead lower and concern more particular cases. The most common cases involve passive shoulder exoskeletons, which, as with active ones, cause a decrease in agonist muscles and an increase in antagonist muscles, as well as, in some cases, an increase in body temperature, particularly in hot environments, resulting in a deterioration of working conditions [28; 38]. Although results cannot be drawn at a general level due to the small number of hybrid exoskeletons investigated, only positive reactions have been observed for these devices, corresponding with those shown for passive exoskeletons.