## 1 Introduction  
Soccer is a sport that demands frequent high-intensity actions, particularly explosive acceleration sprints, which are crucial for success during matches. During competitive play, soccer players typically perform 91-119 high-intensity accelerations (\(\geq\)2.5-3 m/s\({}^{2}\)) and 16-27 sprints (\(\geq\)24-25.2 km/h) with incomplete rest periods of between approximately 30 s or less and 60 s [1, 2, 3, 4, 5]. Short sprints (\(\leq\)10 m) and straight-line sprints are the most frequent movements preceding goal situations in soccer matches, with elite players exhibiting greater sprint distances and higher acceleration frequencies than non-elite players [6]. Recent research has shown that in both adult and youth players, explosive initial acceleration (\(\leq\)20 m) during matches and sprint performance decline as the season progresses [7, 8, 9, 10, 11, 12]. Therefore, repeatedly performing and improving explosive acceleration sprints throughout matches and seasons is a key factor for better performance. Soccer players often perform sprint training with short rest intervals (\(\leq\)60 s) to improve their ability to perform repeated sprints [13, 14, 15, 16, 17, 18]. Adaptation to these short rest intervals between sprints can enhance recovery mechanisms and the activity of enzymes involved in both aerobic and anaerobic energy production [19]. Therefore, coaches may attempt to reduce rest intervals or increase training volume to achieve high intensities, but this approach could lead to exhaustion, and adversely affect sprint mechanics [14, 17, 20, 21, 22, 23, 24]. Moreover, while players and coaches often expect this training to enhance explosive acceleration from the start (0-20 m), research has revealed that it works best at 20-30 m [15, 18, 25, 26]. In this study, the term sprint mechanics is employed due to its direct relevance to the measured variables, which are inherently linked to the mechanics of sprinting. Numerous previous studies have used the term sprint mechanics. Explosive acceleration sprints require producing horizontal forces in the anterior-posterior (AP) direction onto the ground with effective mechanics to reduce braking forces and enhance propulsion [10; 27; 28; 29; 30; 31; 32]. However, continued training with altered sprint mechanics due to short rest intervals could affect athletes' movement patterns as they adapt to compensated sprint patterns [13; 14; 17; 21; 22; 23; 33]. This adaptation can cause changes in the maximum velocity sprint mechanics and performance [28; 30; 34; 35]. To address these issues, several researchers have studied methods to maintain high sprint performance during repeated sprint training by manipulating the distance, rest periods, and volume distribution [22; 36; 37; 38; 39]. However, these attempts have been limited to improving the sprint mechanics and ground force output directly and, also, the opportunity for enhancement and adaptation of the energy metabolism system required by soccer players may be reduced. Resisted sprint training is a primary method of improving short sprint performance in soccer players [26; 40; 41; 42; 43; 44]. It can enhance the horizontal force output in the AP direction and mechanical efficiency by adjusting the trunk angle to effectively accelerate the body forward [40; 44; 45; 46; 47; 48]. Recent studies have shown that loads of 30-50% sprint velocity decrement (Vdec; a load of percentage decrement to the maximum sprint velocity) are effective for initial acceleration mechanics (0-20 m) and have been used in practice and research [28; 40; 41; 47; 49; 50; 51]. However, traditional resisted sprint training has been biased toward improving mechanics and single sprint performance without considering the metabolic stresses required by soccer players. Coaches should consider not only sprint mechanics to improve the amount and direction of horizontal force applied to the ground but also physiological loading to enhance the capacity for repeated explosive acceleration.