## 1 Introduction  
Judo is a dynamic martial art that demands athletes execute swift and powerful techniques in matches that can last from a few seconds to 20 min, depending on when a score is achieved [1]. Moreover, success in judo is closely linked to the ability of an athlete to capitalize on brief moments of opportunity with agility, power, and speed [2; 3]. Due to the high-intensity nature and demand of the sport, a well-structured warm-up is essential for optimizing performance by enhancing physiological factors such as joint flexibility, metabolic efficiency, and neural activation [4]. A key component of an effective warm-up is the addition of conditioning activities that can induce post-activation performance enhancement (PAPE), a process where preceding high-intensity activity enhances subsequent muscle contractility and force production [5]. The underlying mechanisms of PAPE include increased muscle temperature, intramuscular fluid accumulation (i.e., muscle blood flow and/or water), decreased muscle pH, and increased neural drive (i.e., greater muscle activation) [5]. Various conditioning activities have been studied to induce PAPE across different athletic populations. However, as per the author's knowledge, only two studies have been conducted on judokas' judo-specific performance assessed using the special judo fitness test (SJFT) [6; 7]. One study [7] reported that contrast-training exercises that included 2 repetition maximum (RM) squats combined with 5 horizontal jumps improved the SJFT index in male judokas. In addition, the authors also included incremental pyometric box jumps (i.e., 20 cm to 40 cm to 60 cm) as another conditioning activity. They reported an increased number of throws in the first set of the SJFT compared to a traditional judo warm-up (i.e., control) [7]. Similarly, another study [6] reported an increased number of throws in the first set of the SJFT after two conditioning activities. The first conditioning activity involved standing long jumps (i.e., lower body exercise). In contrast, the second one involved standing long jumps and resistance band pulls (i.e., a combination of upper and lower body exercises). Although the previous two studies [6; 7] have reported improved SJFT performance after the included conditioning activities (read the previous paragraph), various conditioning activities have been studied in the past two decades to induce the PAPE effects across different athletic populations. For example, [PERSON], et al. [8] reported improved sprint performance after performing a set of heavy squats compared to control conditions (i.e., warm-up) among football athletes. Another study included a combination of different ballistic jump exercises and reported improved performance among athletes. However, the previous studies that included judo athletes used either a combination of heavy squats with jump exercises [7] or only a single jump exercise (e.g., standing long jumps, pyometric box jumps) [6; 7]. Therefore, it would be interesting to see if performing squats alone or a mixture of different ballistic jump exercises can induce a PAPE effect on specific judo-specific performance. It is also worth noting that both the previous PAPE studies on judo athletes were conducted on adult participants, reflecting a necessity for studies on younger participants. Evidence from other sports suggests that junior athletes could benefit from conditioning activity protocols focused on inducing PAPE, but the literature on this topic in junior judo athletes remains scarce [9; 10]. Therefore, this study aimed to address this gap by examining the acute effects of squat and ballistic jump as conditioning activities during warm-up protocols to induce PAPE in young male judo athletes (participating in sub-junior competitions) using the SJFT as a performance measure.