## 4 Discussion
Significantly larger normalized RTDPEAK in junior players can be explained with their lower body mass index (Table 1), since it is known that lean body mass is associated with greater RFD/RTD [20]. On the other hand, differences in abilities such as kRTD-SF, which is independent of the body mass and muscle size, have not yet been investigated in relation to age. TMVC of elbow extensors, volar flexors as well as kRTD-SF values of both muscle groups showed similar values in junior and senior basketball players (Table 3). There is a paucity of literature analysing the differences in muscle capacity between junior and senior elite basketball players, especially regarding the upper body. A previous study reported that senior basketball players produce significantly higher absolute power with lower extremities [21]. Our data suggest that there is no difference in neuromuscular quickness (as tested by kRTD-SF), between juniors and seniors. On the other hand, some studies that assessed shooting and passing actions showed that more experienced basketball players exhibit a shorter duration of muscle activation of the arm muscles [15; 16]. This could be due to the changes in motor pattern activity associated with increasing skill [22] and not due to the changes in neuromuscular quickness. In accordance with previous studies [12; 14], we have also confirmed that the players with more training experience have better shooting performance, but only from short distance. It is known that the shooting movement pattern changes with greater shooting distance, while its accuracy significantly decreases [23]. Overall, our results suggest that senior players do not have higher strength capacities compared to junior players, while they are equalized in shooting performance at long shooting distance. Thus, we can reject our first hypothesis. Shooting performance was related with kRTD-SF and TMVC only in junior players. This result suggests that muscle abilities such as neuromuscular quickness and TMVC play an important role in shooting performance only in junior players, whereas in seniors their shooting muscles exceed the level of strength capacities required for successful shooting performance. In more experienced players, the shooting performance is influenced by the pattern of muscle activity (i.e., shorter or longer duration from the beginning of muscle activity, lower average activation time) [15; 16] and likely not by the capacity of the shooting muscles. A very strong positive association between elbow extensor TMVC and shooting performance from long distance shows that muscle strength is more important for shooting performance from longer distance in juniors compared to seniors. On the contrary there was no associations between TMVC and shooting performance from short distance. Junior players with higher elbow extensors TMVC were more successful at shooting performance from a long distance (Figure 4e), which highlights the importance of muscle strength in the accuracy task from such distance. We can speculate that junior players with a smaller TMVC were closer to their maximum strength capacity when they performed shots from a greater distance. This can be supported with findings from one study, which showed that the accuracy decreases when the shot is performed closer to the maximal strength capacity [24]. Such associations have been only approaching statistical significance for volar flexors. Likely, it seems that the elbow extensors play a more important role than wrist muscles in providing the force required for the ball to reach the basket at greater distances [11]. On the other hand, RTDPEAK was not associated with shooting performance which could be explained by the fact that basketball shots are not performed under conditions that acquire maximal rate of force development. Significant large positive associations were calculated between kRTD-SF of both muscle groups and the shooting performance from short distance in juniors, while kRTD-SF of both groups was in large negative association with long distance.