# The Influence of Effective Mass on the Striking Force of Lead Jab and Rear Cross Punches of Boxers
## 1 Introduction
It describes the effective mass (Me) involved in a strike, where Fmax represents the maximum force with which the strike was performed, and \"a\" stands for the maximal acceleration before contact with a target. In essence, it quantifies how the effective mass relates to the force and acceleration during the strike. In sports biomechanics, there is the concept of kinematic chain, which refers to a series of body segments connected by joints. These segments and joints work together to generate movement. Understanding the kinematic chain is crucial for analyzing and improving sports movements [7]. In boxing, every movement, both offensive and defensive, utilizes different elements of the kinematic chain and degrees of freedom. The more muscles are involved in the movement, the greater the total generated force. In the case of a punch in boxing, engaging a greater number of muscles, such as leg, hip, torso, and arm muscles, can lead to increased total generated force. This means that coordinated involvement of multiple muscles in the kinematic chain can contribute to more effective force generation and more efficient execution of boxing technique. A greater degree of freedom in a given movement may result in higher total generated force [1]. Sports biomechanics have reached a state-of-art level of use of measurement equipment, which is composed of capturing spatiotemporal data alongside measuring a force of a strike. Variables such as velocity and acceleration are captured using stereophotogrammetry with systems like VICON [8], or with inertial measurement units (IMUs) [9]. Both systems have their advantages; however, the simplicity of setup with IMUs makes them more and more popular, especially with current improvements of those devices, reaching up to 400 g acceleration capacity, suitable for capturing strike-related data [4]. Force plates measure ground reaction force, but are often customized to be used as a striking areas [4]. This could not be obtained without modifications, as force plates are solid-metal coated. They need to be padded with shields, which leads to differences in initial setups between biomechanics laboratories. Another option is to place shields on beams and use inertia/momentum measurements to compute the force of a strike [10]. Force platesand motion capture systems can be integrated by syncing them to match the timing of measurement end ensure its accuracy. This solution is popular and allows scientists to explore different concepts of kinesiology phenomena in combat sports, such as the discussed concept of body mass presented in this work. Observations indicate a correlation between effective mass and striking force [2]. Further examination of this correlation may contribute to a better understanding of the mechanisms shaping the performance of boxers and lead to the identification of key factors influencing the effectiveness of their punches in relation to participant weight. Therefore, this study focuses on the kinetic analysis of straight punches of boxers, taking into account the role of effective mass. The aim of this study is to identify the relationship between effective mass and striking force and understand how effective mass influences the performance of the straight punch technique. The adopted approach will allow a deeper understanding of the biomechanics of boxing and potentially contribute to improving training methods and enhancing athletes' performance. The aim of this study was to gain knowledge on how effective mass affects the striking force of boxers. Therefore, the following research questions were formulated:  
1. What values of effective mass and impulse of striking force and movement pattern did the studied boxers achieve? 2. What relationship does effective mass exhibit with striking force in the applied movement pattern? 3. How does obtained biomechanics and somatic variables affect effective mass? 4. Are there significant differences in values of effective mass between the lead jab and rear cross techniques?