en بيومکانيک ورزشی و شاخه‌های وابسته بدان Sport Biomechanics and its related branches مقاله اصیل Original Article <div style="text-align: justify;"><strong>Background.</strong> Jump landing tasks are frequently employed as a non-specific tool to quantify the capabilities of the lower extremity performance and athletes&#39; injuries.<br> <strong>Objectives.</strong> This study aimed to investigate the relationships between jump height (JH) and ground contact time (CT) in countermovement jump (CMJ) and drop jump (DJ) with assessment indicators such as reactive strength index (RSI), eccentric phase rate of force development (ERFD), peak rate of force development (PRFD), average velocity (EV), amortization phase time (AT), peak ground reaction force (PF), concentric phase average force (CAF), and vertical stiffness.<br> <strong>Methods.</strong> This study was cross-sectional, with 23 participants completing CMJ and DJ tests. Ground reaction force and center of mass displacement data were captured using a motion system and force platforms. Paired-sample t-tests were used to compare differences between CMJ and DJ in JH, CT, ERFD, RSI, and CAF. Spearman rank correlation analysis was conducted to examine the correlation between vertical stiffness and other variables, while Pearson product-moment correlation was used to identify correlations among other variables.<br> <strong>Results. </strong>JH was comparable between CMJ and DJ (p=0.14), whereas significant differences were noted in CT (p<0.001), ERFD (p<0.001), RSI (p<0.001), and CAF (p=0.01). In CMJ, significant positive correlations were identified between JH and RSI, PF, and CAF (RSI: r=0.44, p=0.036; PF: r=0.48, p=0.022; CAF: r=0.55, p=0.007). Moreover, CT exhibited a significant negative correlation with RSI, ERFD, and PRFD (RSI: r=-0.66, p=0.001; ERFD: r=-0.47, p=0.025; PRFD: r=-0.44, p=0.034) and a significant positive correlation with AT (p>0.05). During DJ, JH was significantly positively correlated with CAF and RSI (RSI: r=0.76, p<0.001; CAF: r=0.66, p<0.001), whereas CT was significantly negatively correlated with RSI (r=-0.48, p=0.021). Notably, increasing the drop height altered these relationships.<br> <strong>Conclusion.</strong> These findings collectively reveal that CMJ and DJ differ in influencing factors, suggesting that athletes should tailor their training strategies according to the type of jump.</div> Plyometric Exercise, Jumping, Athletic Performance, Muscle Stretching Exercise. 0 0 http://aassjournal.com/browse.php?a_code=A-11-2321-2&slc_lang=en&sid=1 Maolin Dong maolin0017@163.com 100319475328460015256 0009-0005-5211-2842 No College of Wushu, Henan University, Zhengzhou, China Youngsuk Kim ys43530@jbnu.ac.kr 100319475328460015257 100319475328460015257 No Department of Physical Education, Jeonbuk National University, Jeonju, Korea Yanjia Xu xuyanjia0816@jbnu.ac.kry 100319475328460015258 0009-0005-8634-4633 No Department of Physical Education, Jeonbuk National University, Jeonju, Korea Bin Zhu yuebao486@jbnu.ac.kr 100319475328460015259 0009-0008-6015-3662 No Department of Physical Education, Jeonbuk National University, Jeonju, Korea Ming Li lming@jbnu.ac.kr 100319475328460015260 0009-0002-3553-6932 No Department of Physical Education, Yantai University, Yantai, China Sukwon Kim rockwall@jbnu.ac.kr 100319475328460015261 100319475328460015261 Yes Department of Physical Education, Jeonbuk National University, Jeonju, Korea