## 4 Discussion  
The results of the present investigation showed significant relationships between the muscle architecture and the muscle performance in high-level FH players. In particular, the FL of the VL were correlated with the 30-m sprint performance. This is consistent with  
Figure 5: Scatter plot between Body Fat and PRO. PRO = pro-agility test. The middle line represents the median and the parabolic lines represent the 95% confidence interval. Figure 6: Scatter plot between Body Fat and 30-m Sprint. The middle line represents the median and the parabolic lines represent the 95% confidence interval. [PERSON] et al. [6] and [PERSON] et al. [8] who reported significant associations between FL of VL and the sprint performance in both female and male sprinters. Muscle FL has been suggested to play an important role in determining the maximum contraction velocity of the muscle [22] and consequently the maximum sprint ability [23]. Indeed, longer fascicles warranted higher contraction speeds through a greater number of sarcomeres in series than shorter FL [24]. The present investigation also showed a significant correlation between the PA and both sprint and agility performances. Greater PA may allow to attach more contractile tissue to a given area of tendon [25] but it may negatively affect the contraction speed [24]. On the contrary, smaller PA and relatively higher FL may represent an advantage for power and speed performance [6]. Increased PA and reduced FL have been reported in trained individuals following resistance training programs [26; 27]. On the contrary, increases in FL and reductions in PA were obtained in competitive athletes of both sexes following a 5-week training program including both resistance and sprint/jump training [25]. Both FH conditioning and games included several different stimuli such as changes of direction and sprint that may alter the muscle morphology. In addition, all the participants in the present study performed at least 2 resistance training sessions per week in the last 2 years. As reported by [PERSON] et al. [25], the concurrent action of resistance training and power/speed activities may lead to significant changes in the muscle architecture. To date, only one study investigated the relationships between muscle architecture and agility [15], and no significant correlations between MT, PA or FL of VL and the agility t-test were found. The agility t-test, however, does not include only changes of direction and sprint, but also lateral shuffles and backward running that are influenced by the individual motor coordination. The presence of these movements may have reduced the correlation between the agility performance and the muscle morphology. No significant correlations have been detected between MT and maximal strength. Despite the muscle dimension represents a determinant factor for maximal force production, VL may not be the most important portion of quadriceps for maximal force production in the squat exercise. Furthermore, the lack of significant correlation with both maximal force and pRFD and a low level of intraclass correlation for pRFD20 may be due to a short familiarization phase preceding the ISQ assessment. The main limitation of the present investigation was represented by the insufficient familiarization of the participants to the strength and power assessments performed. In particular, FH players participating in the study were not completely accustomed to the ISQ test. The pro-agility test has been extensively used among different populations of athletes. Normative data were presented for NCAA Division I College Basketball, Baseball or American Football [28]. The 90-percentile performances of 4.22 s, 4.25 s and 4.21 s were reported for Basketball, Baseball and American Football players, respectively. The pro-agility test was also included in the NFL and 90-percentile performances between 3.89 and 4.45 were reported for defensive back and offensive linemen players, respectively.