## 1 Introduction  
The construction industry is characterized by demanding physical labor, requiring workers to carry heavy materials, perform repetitive bending and standing motions, and assemble structures at elevated heights--tasks that impose significant physical strain [1, 2, 3, 4, 5, 6, 7, 8]. These physical demands contribute substantially to worker fatigue and musculoskeletal injuries, which in turn lead to reduced work speed, diminished productivity, and increased risk of accidents [9, 10, 11, 12, 13, 14, 15]. Despite various technological approaches aimed at enhancing construction productivity, many operations remain heavily dependent on manual labor [16; 17; 18; 19; 20; 21]. Consequently, there is a growing need for assistive technologies that can simultaneously reduce physical strain while improving productivity [22; 23]. Wearable exoskeletons have emerged as a promising solution to address these challenges [24; 25; 26; 27; 28]. These robotic systems assist users' physical movements, reducing muscle fatigue and potentially enhancing work efficiency [29; 30; 31; 28]. Particularly in construction environments that involve repetitive lower-body movements, wearable robotic exoskeletons are increasingly recognized as effective tools [32; 33]. These devices supplement lower-body strength, reduce fatigue during heavy material transport and maintain postural stability during prolonged standing work [34; 35; 36]. Previous studies have examined the potential of wearable robots to reduce physical burden and improve work stability in construction activities. For instance, [PERSON] et al. [37] experimentally demonstrated that wearable robots can help maintain safer worker postures during construction tasks. [PERSON] et al. [38] analyzed safety factors and potential risks associated with wearable robot usage, discussing how these assistive devices can reduce physical strain while acknowledging that user adaptation and the physical characteristics of the robots influence work efficiency. [PERSON] et al. [39] examined the physiological impacts of powered back-support exoskeleton in construction settings. While these existing studies have shown that wearable robots can contribute to reducing physical burden and improving work safety, there remains a notable gap in quantitative analysis of whether wearable robots directly enhance productivity through increased work output in actual construction environments [40; 41]. Objective data regarding how much work output increases relative to cost is essential for improving industry's acceptance of this technology [42]. Lower-body robotic exoskeletons also represent a promising area for future research, as there remains significant potential for optimizing these systems, specifically for construction applications where workers frequently engage in demanding lower-body movements, such as lifting, carrying, and repetitive bending [43; 44; 45; 46; 47]. Even though many construction activities involve lower-body movements, such as walking, carrying, and postural adjustments, empirical research on productivity enhancements from lower-body assistive devices in actual construction sites remains limited [44; 48; 49]. This study gap impedes the assessment of wearable robotic technology's practical value and the development of industry-optimized solutions. This study aims to address this research gap by experimentally analyzing the impact of robotic exoskeleton usage on actual work productivity. While previous research has established that wearable robots can effectively reduce workers' physical burden [50; 51; 52], this study takes a step further by quantitatively measuring whether robotic exoskeletons increase the volume of completed work within the same time. In addition, this study comprehensively evaluates the practical effects of wearable robots by analyzing their physical stability and ability to maintain balance.