###### Abstract  
Understanding the reliability of jump testing is essential to determine the neuromuscular progress of athletes and make informed decisions. This study aimed to assess the reliability of several countermovement jump (CM)) and drop jump (DJ) test metrics in female volleyball players. Sixteen (\(n=16\)) semi-professional female volleyball players participated in this test-retest study. Intrassession and intersession reliability of CMJ and DJ metrics were evaluated using a randomized cross-over design. A dual force platform was used to collect CMJ and DJ data, and several dependent variables were calculated using forward dynamics. Intraclass correlation coefficients (ICC), coefficients of variation (CV), and minimum difference (MD) were calculated to assess intra- and interday reliability. During the same testing, the third attempt consistently yielded the highest values for both tests in jump height but presented excellent reliability (CMJ: ICC [95%CI] = 0.97 [0.93-0.99]; CV [95%CI] = 4.1% [1.2-7.0]; MD95 = 3.5 cm; MD90 = 2.9 cm; DJ: ICC [95%CI] = 0.91 [0.77-0.97]; CV [95%CI] = 6.7% [1.9-11.5]; MD95 = 6.0 cm; MD90 = 5.0 cm). CMJ height exhibited excellent reliability between sessions (ICC [95%CI] = 0.93 [0.81-0.97]; CV [95%CI] = 3.8% [1.1-6.4]; MD95 = 3.5 cm; MD90 = 3.0 cm), whereas DJ height demonstrated slightly lower but still acceptable intersection reliability (ICC [95%CI] = 0.81 [0.55-0.93]; CV [95%CI] = 6.1% [1.7-10.4]; MD95 = 5.2 cm; MD90 = 4.4 cm). Intersection reliability for CMJ kinetics and kinematics was excellent for 13 of the 24 metrics assessed. For DJ, only concentric (ICC [95%CI] = 0.91 [0.76-0.97]; CV [95%CI] = 3.0% [0.9-5.2]; MD95 = 15 Ns; MD90 = 12.6 Ns) and eccentric impulses (ICC [95%CI] = 0.99 [0.96-0.99]; CV [95%CI] = 1.7% [0.5-2.9]; MD95 = 9.2 Ns; MD90 = 7.7 Ns) demonstrated excellent intersession reliability. Most CMJ variables showed excellent reliability within sessions, while DJ had lower reliability in most metrics. These findings provide valuable information to physical trainers to select the metrics to assess athletes' performance as well as to identify a minimum cut-off value that serves as a reference for each of the metrics reported in both tests. reliability; force platform; countermovement jump; drop jump; volleyball; CV; ICC; women; sport; jump +
Footnote †: journal:both the CMJ and the drop jump (DJ) have demonstrated being the two vertical jump tests that exhibit prolonged performance decrements post-exercise, suggesting an extended sensitivity compared to other tests such as the squat jump (SJ) or 20 m sprint times [16]. Therefore, the assessment of vertical jump performance can be used as a valuable tool for coaches and trainers to monitor athletes' physical progress and make informed decisions based on objective estimations of the neuromuscular system function. These tests have been studied in various populations, especially the CMJ [4; 6], but research is limited regarding the reliability of these tests in female athletes specialized in jumping. Most studies that have examined the reliability of vertical jump tests have been predominantly conducted in non-specialized sports populations for jumping (i.e., vertical jumping is not the primary movement pattern during competition and/or training). The characteristics of the specific sports activity can lead to adaptations over time in contraction time and force production, both in CMJ and DJ, providing different jump patterns as previously explained through principal component analysis [17]. On the other hand, when the reliability of these tests has been analyzed in volleyball populations, the research has primarily focused on men. However, none of these studies have reported on the absolute and relative reliability of jumping metrics of both tests in female volleyball players, despite possible differences that may arise due to athletes' sport background and gender [18]. Furthermore, force plate jump testing is becoming more accessible to training coaches due to advances in technology and reductions in cost [19].