## 2 Materials and Methods
### Data Processing and Data Analysis  
The process of data acquisition involved capturing five strikes for each technique per participant. Initially, the data were extracted from the measurement software (Noraxon MR 3.18 with Myomotion module) in the Excel *.slk format and later converted to *.xlsx format for improved processing. The Python script, utilizing the SciPy library and the findpeaks function, was employed to determine the maximum force. The code involved uploading data to the Deepnote platform, facilitating real-time collaboration on data projects. It encompassed the conversion of raw data to m/s\({}^{2}\) and peak detection. Given that data were collected for five strikes per file, the code identified events (strikes) around the maximum force value at a specific strike, subsequently pinpointing the acceleration values of each marker at the time of maximum force. Each trial was segmented into five strikes, and the code specified the duration of each strike, along with the maximum impact force and acceleration of individual limb segments. To select the data, it was assumed that the strike began when the fist reached an acceleration of 12 m/s\({}^{2}\). The accelerometers were correlated with the Earth's acceleration, assumed to be 10 m/s\({}^{2}\). The time difference in reaching values between 11 m/s\({}^{2}\) and 12 m/s\({}^{2}\) was marginal. Therefore, to eliminate measurement errors, the threshold for the beginning of the movement was set to 12 m/s\({}^{2}\). A specific moment of strike was identified when the fist initiated contact with the target, and the GRF (Ground Reaction Force) value began to rise. The end of the strike was defined as the moment of reaching the maximum value of GRF. The accelerations of the fist, forearm, and arm reached their highest values only after the completion of the strike, due to the rapid rebound of the limb after contact with the target. Code is available at the GitHub repository via link [[https://github.com/Dareczin/boxing_biomechanics](https://github.com/Dareczin/boxing_biomechanics)]([https://github.com/Dareczin/boxing_biomechanics](https://github.com/Dareczin/boxing_biomechanics)) (accessed on 22 February 2024). All the variables' code names used in this study are the same as those used in the provided code and left on purpose for transparency and reproducibility standards. Graphical representation of a single strike and the way of defining variables are presented in Figure 4.  
Figure 3: Example of participant’s lead jab and rear cross with the view for force plate with padding, imitating shield. All analyses were video-supported for additional feedback during computation of results. Following data collection, which included maximum force values on the platform and changes in hand acceleration, the information was organized in Excel using Microsoft Office Professional Plus 2010, categorizing it by strike type and left or right arm. Consequently, data aimed for 130 measurement positions (13 individuals \(\times\) 5 strikes \(\times\) 2 arms), but we were able to extract 111 strikes. For the purposes of statistical analysis, the data were exported to Statistica 13 software (TIBCO Software Inc., Santa Clara, CA, USA). Subsequent calculations included basic descriptive statistics and the Shapiro-Wilk test was conducted to assess normality. The Mann-Whitney U-test was employed to determine the significance of differences between groups. Additionally, [PERSON]'s correlation coefficients were calculated to ascertain the presence of interdependencies between the variables under examination. Statistical significance was set at \(p\) < 0.05. Based on the results of the Shapiro-Wilk test, with a significance level of \(\alpha\) = 0.05, we rejected the hypothesis of normal distribution for the variables 'age', 'body mass', 'height', 'training tenure', 'total GRF', 'afist','aforearm', and 'aarm', as all \(p\)-values were less than 0.0001. To establish the necessary sample size for our study, we performed an a priori power analysis (G*Power) employing the Mann-Whitney U-test.