## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**MRFS20m** & **R = 0.486** & **R\({}^{2}\) = 0.236** & **F(2,115) = 17,776** & \(p<0.001\) & **SEE 0.092** \\ \hline
**UHCJ20m** & **b \({}^{*}\)** & **Part. r** & **b** & **Rssquare** & **t (114)** & \(p\) \\ \hline SL & \(-\)0.607 & \(-\)0.469 & \(-\)0.228 & 0.417 & \(-\)5.687 & 0.000 \({}^{*}\) \\ CT & 0.538 & 0.425 & 0.002 & 0.417 & 5.041 & 0.000 \({}^{*}\) \\ \hline \end{tabular} Legend: UHCJ20m— unilateral horizontal cyclic jumps 20 m, MRFS20m—20 m flying start run, R—coefficient of correlations, R\({}^{2}\)—coefficient of determination, F—f test value, SEE—standard error of the estimate, b\({}^{*}\)—regression coefficient, Part.—partial correlation coefficient, b—non-standardized regression coefficient, t—value, SL—average step length, CT—average contact time, \({}^{*}\) significant at \(p\leq 0.05\).  
\end{table} 
Table 6: Results of stepwise forward regression analysis of the set of kinematic parameters of the UHCJ20m test and the results in the MRFS20m test. regression analysis used to determine the correlation between the predictor variable, the result in the UHCJ20m test, and the result in the MRLS20m test showed a statistically significant correlation (Table 2). Along with this result, it was expected that the correlation coefficient of the results obtained in these two tests would be higher because the existing data on horizontal jumps showed a greater correlation with sprinting at 5, 10, 20, and 25 m. The correlation coefficients differ with respect to the type of jumps (bilateral, unilateral, or cyclic) and the length of the distance used to measure start acceleration, varying from r = 0.66-0.86 [5, 9, 20, 21, 24]. The start acceleration run consists of several phases: the initial acceleration from 0-12 m, characterized by a constant increase in stride length; the main acceleration from 12-35 m; and the third phase, which is present only in elite sprinters and occurs from 35-60 m. Elite sprinters reach the maximum running speed between 50 and 70 m [11, 41, 42, 44]. According to the available research studies [38], student athletes reach maximal running speed around 30 m, which implies lower speed in the first phase of sprinting as well as in the phase of running at maximal speed. Due to the similar movement pattern and the exertion of a large concentric force and thus a large running speed during the acceleration phase, horizontal jumps have shown a great predictive value for the start acceleration run [11, 22, 45]. [PERSON] and [PERSON] [46] suggested horizontal jumps as a specific exercise for the development of start acceleration. The reason why a lower correlation coefficient was found in this study than in other studies could be due to an insufficient level of motor knowledge and lower extremity muscle strength of the subjects. The subjects learned and practiced block starts during class, but the number of iterations may not have been sufficient for the subjects to master the movement structure at a serious level because starts and block clearances are very complicated movement structures. In research studies that investigated the relationship between jump and start acceleration and running speed, in most cases, subjects performed 5 m, 10 m, 20 m, or 30 m sprint tests from a standing position, which allowed them to achieve a higher speed over shorter distances [5, 7, 8, 9, 47]. [PERSON] et al. [11] used standing 10 jumps and standing 5 jumps in their test battery, which are structurally similar to the UHCJ20m, only the final outcome is different as these jumps measure the total distance jumped, whereas the UHCJ20m test measures the time taken to complete the task. Standing 10 jumps and standing 5 jumps differ because certain kinematic parameters change when measuring the total length of the jumps, while tests that measure the time required to complete jumps over a given distance require the subject to find an optimal balance between parameters such as stride length and frequency, ground contact time, and flight time.