###### Abstract  
Falls at height are among the major causes of fatal accidents at work, especially in the construction sector. Maintaining balance while performing a tool with both hands generates physical efforts and mental loading that needs to be managed for workers' safety and health. The purpose of the study is to compare perceived (dis)comfort (overall and localized), the ergonomic risk, and the perceived effort through the acquired postures that subjects assumed during the execution of simple and common tasks both on a ladder and on the ground. 26 subjects were asked to perform four tasks in both conditions: top screwing, frontal screwing, object picking from the bottom forward, and object picking from the bottom sideways. Subjective and objective data were gathered for assessing subjective experience (discomfort and effort, perceived) and ergonomic risk. Results highlighted few ergonomic risk differences among \"on ladder\" and \"on ground\" tasks, while subjective data reveal significant differences in different scenarios. Furthermore, the knees and neck areas are the most critical ones.  
working at height; ladder; discomfort; ergonomics; hand tools +
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phases, and incentivize formal training programs and regulations governing the use of ladders [1; 6; 9; 15; 22; 23].  
Little scientific research has been carried out to ergonomically evaluate the ascent, the descent, and the handling of ladders in working activities [3; 24]. The most investigated factors regard heavy loads and manipulation of objects while working at heights; incongruous posture, and repetitive arm use; loading/unloading ladders from vehicles; and placing ladders on the shoulder to move them. Some studies have been conducted, especially in the agricultural sector, and during apple harvesting operations [25; 26; 27; 28; 29]. In [25; 26], two different apple harvesting methods were compared: a conventional ladder and a newly developed mobile platform. In [28; 29], the analysis carried out using the RULA [30] method is aimed at identifying uncomfortable postures/activities that occurred during apple harvesting. In [24] the aim was to compare mechanical load, safety, energetic workload, perceived exertion, and perceived discomfort, among window cleaners that used some extension ladders with 30 and 35 cm rung separation. The biomechanical aspects relating to the daily use of the ladder have received very little attention, in particular, on the musculoskeletal load required and the postural discomfort perceived during its usage. Subjective and/or objective data can be useful to evaluate postural (dis)comfort regarding a generic task. To detect the subjective data (pain, discomfort, and level of fatigue), surveys, questionnaires, and self-reports are used. The most used are the BPD: Body Part (Dis)comfort and the LPD: Localized Postural (Dis)comfort [31; 32; 33]. To detect the objective data (ergonomically valid posture and postural comfort), sensors, methods, and tools are used [34; 35]. The software CAMan [36; 37; 38; 39; 40] considers the angles assumed by the upper limbs during the execution of a task and gives an output of a postural comfort index. The tool, realized by the University of Salerno, gives the comfort index on a 10-point scale where 10 is the maximum.  
The reason for this study was born in this context. The aim of this study was to examine joint loading along with ratings of perceived discomfort and perceived strain during a simple work task with and without the use of a ladder. The research questions are: How much does performing a simple task on a ladder instead of on the ground affect perceived discomfort? Is the difference in perceived discomfort related to biomechanical overload (evaluating it with the RULA method)?