###### Abstract  
The association between force-time characteristics of isometric leg press (ILP) and counter-movement [jump (CM)] with vastus laterals (VL) muscle architecture, was examined in 19 female athletes (aged 23.2 \(\pm\) 5.4 years). Peak force (PF), average rate of force development (ARFD) and rate of force development (RFD) at different time epochs were calculated from the force-time curve, as well as CMJ jump height and power. Significant correlations were found between ILP-PF and CMJ power (\(r\) = 0.658, \(p\) < 0.01), while both variables were correlated with VL thickness and fascicle length (\(r\) = 0.471 to 0.648, \(p\) < 0.05). Significant correlations were also observed between ILP-RFD epochs and VL fascicle length (\(r\) = 0.565 to 0.646, \(p\) < 0.05) and between CMJ height with VL thickness (\(r\) = 0.523, \(p\) < 0.05). Furthermore, positive correlations were found between ILP and CMJ in ARFD (\(r\) = 0.625, \(p\) < 0.01) and RFD epochs (\(r\) = 0.464 to 0.566, \(p\) < 0.05). ILP-PF and muscle thickness accounted for 52.8% (\(p\) = 0.002) of the variance in CMJ power. These results suggest that isometric force time characteristics are associated with power generation during dynamic muscle actions. Furthermore, VL muscle thickness and fascicle length are associated with rapid force production in female athletes, irrespective of the type of muscle action.  
s : 1 (2021) 11 (2021) 10.3390/app1115272 11 (2021)  
bench press exercises and [PERSON] et al. (1995) [17] did not observe a relationship between PF achieved during isometric squat and countermovement jump (CMJ) height. In contrast, other studies showed significant relationships between isometric PF and CMJ or squat jump height and peak power [13; 14; 15; 18; 19]. Interestingly, significant correlations were reported between dynamic and isometric muscle actions in well-trained athletes [20] and when standardizing the joint angle during the force-time assessment protocols [21]. Thus, there is conflicting evidence about the link between isometric and dynamic performance [22].  
Among the factors associated with strength and power generation, muscle architectural characteristics are considered as important determinants [23]. For example, longer fascicles increase the ability of force production during high velocity contractions--in particular RFD [24]--and allow for less sarcomere deformation at a given contraction velocity [23; 25]. Greater fascicle penation reflects a greater number of in-parallel sarcomeres, typically associated with increased physiological cross-sectional area and muscle strength [26; 27]. Muscle thickness reflects muscle size and is related to the ability of force production [28; 29]. However, the association between muscle architecture and force-time characteristics of isometric and dynamic muscle actions has not been explicitly studied. A better understanding of the relative contribution of muscle morphology to force generation in different types of muscle actions would help in designing interventions to improve muscle function in athletes, patients or elderly populations. As female athletes have lower power and strength [30], smaller fascicle penation angle and longer relative fascicle lengths than men [31] it is important to investigate the association between muscle performance and architecture in women. Furthermore, evidence on the association between isometric and dynamic muscle actions is limited in female athletes and the relationship between force-time characteristics in different muscle actions and muscle architecture has not been previously examined. Thus, the purpose of this study was to investigate the relationship between muscle architecture and force-time characteristics of isometric leg press (ILP) and CMJ in female athletes.