# Biomechanics of Punching--The Impact of Effective Mass and Force Transfer on Strike Performance
## 4 Discussion
Since optimal force transmission depends on maintaining structural integrity throughout the kinetic chain, training should emphasize controlled deceleration and impact control rather than merely maximizing punching speed. This is a crucial factor, as boxers who effectively utilize pressure force through dynamic leg extension and proper body stabilization can significantly increase their effective punching mass, even with relatively low body weight [17]. Additionally, fist acceleration (\(\beta\) = 0.72, \(p\) < 0.001) and impulse (\(\beta\) = 0.57, \(p\) < 0.001) were identified as key determinants of punching force. While acceleration plays an important role, our results confirm that impulse, defined as the product of force and time, allows for better mass transfer during impact. The comparison of Effective Mass Index values further supports this conclusion. The highest Effective Mass Index value was recorded for the cross (36.77 \(\pm\) 18.83%), followed closely by the jab (35.49 \(\pm\) 16.48%), suggesting that straight punches allow for a more effective utilization of body mass compared to hook punches. The correlation between impulse-to-fist acceleration ratio and effective mass further supports the idea that controlled force application is more crucial than maximum speed alone. It is also worth noting that high effective mass in straight punches may be linked to the ability to stabilize posture at the moment of impact. Fighters who maintain proper body stiffness and minimize unnecessary movements can transfer force to the fist more effectively [18]. Consequently, training should focus not only on developing muscle strength but also on technical aspects of posture control and footwork, which enable efficient use of body mass in the punch [19]. This is consistent with studies on other combat sports, where biomechanical analysis has shown that the utilization of ground reaction forces and postural stability are key factors for strike effectiveness, regardless of an athlete's body mass [20]. In contrast, the effective mass values for hooks were significantly lower: 14.38 \(\pm\) 12.05 kg for the lead hook and 12.56 \(\pm\) 5.52 kg for the rear hook. Despite generating greater ground reaction forces and higher fist acceleration, hooks were not as effective in transferring body mass as straight punches. The lead hook demonstrated an impulse of 42.39 \(\pm\) 7.38 Ns, while the rear hook reached 43.87 \(\pm\) 7.62 Ns, which were significantly lower than the values observed for straight punches. This suggests that hook punches apply force over a shorter time frame, potentially limiting their efficiency in mass transfer. This supports the idea that hooks, despite generating greater ground reaction forces and higher fist acceleration, are not as effective in transferring body mass as straight punches, as this was shown in boxing [21] and kickboxing [22]. Hooks require a wide range of hip and torso rotation, increasing movement dynamics but potentially leading to greater energy losses [23]. Additionally, the biomechanical characteristics of hooks mean that the moment of contact with the target may occur at a slightly different point in the punch trajectory compared to straight punches. While the jab and cross follow a more direct punching path, hooks reach their peak fist velocity when the arm is at the furthest point of its curved trajectory [6]. If the punch is not properly synchronized with the biomechanical peak of energy transfer, the effective mass of the impact may be lower than in straight punches, which utilize a more compact and directional mass transfer. Training strategies should therefore prioritize improving body stabilization at the moment of impact and refining the coordination of hip, torso, and arm rotation to maximize force transmission efficiency. The analysis of body mass's influence on effective mass revealed that there is no linear relationship between these variables. While higher body mass generally facilitatesgreater punching force [1], its impact on effective mass is limited.