## 4 Discussion  
The purpose of the current study was to examine whether there were differences between elite weightlifters and track and field throwers in RFD, lean mass, VL muscle architecture and 1-RM strength. The main finding of the study was that RFD was similar for both groups of athletes, although when RFD was expressed relative to lean mass, weightlifters performed better at 80, 100 and 150 ms. In addition, weightlifters had higher 1-RM strength and higher CMJ height and power relative to body mass compared to throwers. Throwers were taller and had higher trunk lean mass. Weightlifters had longer VL fascicle length compared to throwers, which may partially explain the differences in RFD and CMJ with throwers. These results suggest that longitudinal training (specific for each sport) may induce different muscle adaptations between power-trained athletes, which may lead to further enhanced RFD, power and 1-RM strength. Although many physiological and fitness parameters contribute to performance in power sports, RFD is an important factor for success, especially in weightlifting and track and field throwing events [6; 7; 24; 34]. In the current study, no significant difference was found between weightlifters and throwers when RFD was expressed in absolute values. It can be hypothesized that the high percentage of type II and especially type IIx muscle fibres in throwers [14; 22] and the high percentage of type IIa muscle fibres and percentage type II fibre area in weightlifters [16; 17] may balance the difference between groups during RFD evaluation. As previously mentioned, the early phase of RFD is primarily determined by neural activation [9] by the percentage area of muscle occupied (%CSA) by type II and especially by type IIx muscle fibres [12], whereas the late phase of RFD is mainly determined by lean mass, fibre-type composition, muscle architecture characteristics and 1-RM strength [6; 9; 12]. Considering that the athletes who participated in the current study were all active elite athletes and the evaluations were performed immediately following a national competition, neural adaptations may have been already highly developed for both groups [35; 36], therefore increasing the external validity of the study. However, when RFD was expressed relative to total lean mass, significant differences were found at 80, 100 and 150 ms. Similarly, a previous study of power-trained athletes showed that when RFD was expressed relative to total lean mass, athletes with lower lean mass produced greater  
Figure 2: Performance in 1-RM strength in snatch and back squat (\(\pm\)SD). With (*) denoted the significant difference between weightlifters and throwers. early RFD compared to athletes with higher lean mass [37]. Given that no difference was observed between groups for total lean mass, weightlifters may apply their force more rapidly compared to throwers when RFD is expressed relative to lean mass, especially in the early phase of the force-time curve. Weightlifters achieved higher CMJ height and power relative to body mass compared to throwers. CMJ may strongly predict competitive performance in weightlifting and throwing events [36; 38]. These differences in CMJ and RFD relative to lean mass between weightlifters and throwers may partially be explained by the significant difference in VL fascicle length. We found that weightlifters had approximately 13.8% longer VL fascicle length compared to throwers. Even when VL fascicle length was expressed relative to body height, weightlifters still had approximately 17.1% higher fascicle length compared to throwers, although throwers were significantly taller than weightlifters. Longer fascicle length may produce higher shortening contraction velocities compared to shorter fascicle length and, as a consequence, increased power outputs [39]. Results from a recent study showed that 6 weeks of fast eccentric back squats may increase VL fascicle length, RFD and 1-RM strength in back squat [31].