## 1 Introduction  
In the pursuit of athletic excellence, coaches and researchers are constantly challenged to find safe and effective methods to improve athletic performance. The evolution of training techniques and the incorporation of advanced technologies have played a crucial role in the development of innovative strategies to maximize the physical and mental capacity of athletes. In this sense, transcranial direct current stimulation (tDCS) emerges as a tool capable of enhancing sports performance by modulating neural activity [1, 2, 3, 4, 5, 6]. tDCS modulates cortical excitability, which can result in significant improvements in both cognitive and motor tasks [1]. When a 2 mA current is applied for \(\sim\)15 min, tDCS increases neuronal plasticity in specific areas of the brain [7], such as the dorsolateral prefrontal cortex (DLPFC) and the primary motor cortex (M1). These areas are critical for the planning, execution, and coordination of complex movements [6, 8], as well as for managing mental and physical fatigue during high-intensity exercises [3, 9]. Previous studies have shown that both the prefrontal cortex, located at the top of the motor hierarchy, and the M1, located further down the hierarchy, play critical roles in physical performance [10]. In particular, the importance of the left dorsolateral prefrontal cortex (i.e., DLPFC) in the ability to maintain and complete physical activities has been highlighted through its influence on aspects such as motivation and decision-making [11; 12]. Meanwhile, M1 is essential for transmitting neural instructions from higher brain areas to motor units, which directly influences the muscle's ability to execute specific tasks [10; 13]. These findings suggest that altering activity in these brain areas may influence exercise performance, as well as impact cognitive abilities and physiological responses. Transcranial direct current stimulation has shown promising results in improving endurance, strength, and power output in healthy populations [2; 3; 4; 10; 14]. While much of the previous research has focused on assessing the effects of tDCS on endurance performance in relatively simple tasks such as running or cycling and on muscle strength or power [10], there is a notable paucity of studies addressing its impact on more complex exercises [6; 15] that involve multiple phases and muscle groups, such as the burpee exercise. The burpee is a high-intensity exercise that integrates both strength training and cardiovascular conditioning, commonly used in sports conditioning programs to improve endurance, strength, and power [16]. This complex exercise, which activates multiple muscle groups such as the legs, trunk, chest, and arms, is not only effective in increasing cardiovascular fitness through sustained elevation of heart rate but also in promoting intense metabolic and neuromuscular demand. Given the integral and demanding nature of the burpee, which requires complex coordination and muscular endurance, tDCS could play a significant role in improving athletes' ability to sustain higher volumes of work at high intensity [9]. Stimulation targeting DLPFC and M1 could influence fatigue endurance by modulating neural activity underlying decision-making, cognitive control, and motor performance, which are critical elements during continuous and strenuous repetitions of this exercise. Thus, the application of tDCS before burpees could potentially improve performance by altering how the brain manages both perceived fatigue and actual muscle activation. Given the possibility that tDCS may significantly improve critical aspects of performance in complex exercises, this study focused on extending our understanding of how targeted application of tDCS to specific regions may influence performance during a physically strenuous task such as the burpee, typical of fitness settings. Therefore, the present study aimed to assess whether stimulation of these regions (DLPFC and M1) improves the number of repetitions until exhaustion and reduces the perception of effort.