## 4 Discussion
The present study found that the U-23 group had a trochanter-tibiale length (thigh length) that was significantly shorter than the Olympic group. A possible explanation for this could be that the kayakers from the U-23 group were in the final part of their growing stage, which occurs in the cephalocaudal direction [29], so the femurs could still be growing longitudinally. Along this line, previous studies with young paddlers have found shorter thigh lengths than in the present study [30]. Not surprisingly, in another study with high-performance adult paddlers, similar values were found for the thigh length as reported for the current paddlers [28]. Another important finding was that kayakers from the Olympic group showed significantly higher values in body mass than the rest of the groups, followed by the U-23 group. Previous studies have found that body mass was highly correlated with performance in rowers [31]. Nevertheless, previous studies have shown that muscle mass in kayakers is higher in higher competitive levels than in lower levels [32; 33]. Body mass is a variable that cannot differentiate between fat and muscle mass, and muscle mass has a higher density than fat mass, making it heavier [34], which could justify the differences in body mass between groups. No significant differences were found in height, iliosipinale, and tibiale laterale measurements and foot length, although the U-23 group showed the lowest values, followed by the recreational group, with higher values shown by the Olympic group. This may be explained by the fact that the U-23 group was in their final period of growing, while the others had already completed it [35], although similar heights to the current paddlers have been found in young world-class elite kayakers [32]. Olympic-level kayakers and medalists in world championships were taller than the current sample, although the world-class elite group was closest to the kayakers of the present study [33]. Lastly, the university-level kayakers were shorter than the kayakers of the present study [36]. These results are supported by [PERSON] (2002) who noted that high-performance kayakers were taller than low-performance paddlers. Although a similar trend was found in the present study, significant differences were not found in our sample. Furthermore, it is possible that the competition distance has an influence on this factor, as kayakers who compete in shorter competition distances are usually taller than those who compete in longer distance competitions [37]. Therefore, future research on this matter is necessary. As for the question about whether the placement of elements in the boat was dependent on anthropometric variables, sagittal spine position, or hamstring extensibility, the main finding was that the variable with the highest relationship was the iliosipinale measurement, with an R\({}^{2}\) score of 0.8. This could be due to the fact that the kayaker, who depends on lower limb length, needs to place the seat at a specific distance. This is necessary for flexing the knees in an angle from 110-120 to 147-162 [2; 38] without limiting trunk rotation during the paddling motion to allow for an optimal production of muscle strength, length and type of stroke, and transmission of forces to the boat [13]. This finding is contrary to a previous study, which suggested that the placement of the elements in the boat was dependent on height (R\({}^{2}\) = 0.589) [13]. This discrepancy could be attributed to the study by [PERSON] et al. [13], which did not include lower limb lengths as independent variables. It can thus be suggested that the iliospinale measurement could be the best predictor of the dependence of the boat elements, based on the R\({}^{2}\) scores. Future studies on the current topic are therefore recommended. The main practical application from the present study is the recommended use of the iliospinale measurement as a predictor of the distance between the elements in the boat.