## 4 Discussion
In addition, the swimmers in our investigation presented a range of first MPJ dorsal flexion under 60 degrees, which is considered the normal range [33]. Although this is commonly associated with excessive foot pronation, the FPI of many of the participants did not show pronation. The mild limitation observed might also be a consequence of an imbalance in the calf muscles and plantar musculature affecting the first ray. We observed that the most predominant type of plantar footprint corresponded to a high-arched foot, with no significant differences between the two age groups. [PERSON] et al. [34] reported that overuse of the foot leads to biomechanical adaptations being different in pre- or post-competition. These modifications may become chronic with time, making the foot acquire morphological characteristics that depend on the sports modality. On the other hand, [PERSON] et al. [35] show that the cavus foot is the most predominant type of foot in athletes and swimmers, possibly due to the musculoskeletal adaptations that shape the plantar arch. [PERSON] et al. [36] sustain that, in athletes, the prevalence of pes cavus is higher than in flat feet and that this finding is related to the demands of the foot towards plantar flexion. This could also affect the normal distribution of plantar pressure. In this work, the athletes presented a higher percentage of load in the rearfoot, both juniors and adults, which may be normal in unshod feet. [PERSON] et al. [37] mention that the distribution of plantar pressure in pes cavus is significantly greater in the rearfoot due to the fact that the arch elevation reduces the contact surface, increasing plantar pressure. The findings of this study highlight a predominance of this specific foot type among competitive swimmers, which may be associated with the biomechanical demands imposed by the sport. The sustained plantar-flexed position of the foot and forefoot during stroke execution, particularly in propulsive phases, could contribute to morphological adaptations over time. This forced positioning may influence both musculoskeletal loading patterns and structural characteristics of the plantar region, potentially predisposing athletes to specific mechanical stresses. The statistical findings obtained in the study have significant scientific and clinical importance, as ankle dorsiflexion is directly related to injury risk and sports performance in swimmers. Limitations in dorsiflexion can alter the biomechanics of the kick, increase tension in the posterior leg muscles (such as the triceps surae), and predispose athletes to overuse injuries, such as Achilles tendonopathy, plantar fascitis, and tibial stress syndromes. This is particularly relevant in swimming, where repetitive movements and high joint loads make even small clinical variations in dorsiflexion significant. Studies such as those by [PERSON] et al. [28] and [PERSON] et al. [29] support that limited dorsiflexion affects kick efficiency, reduces propulsion, and increases the risk of muscle fatigue and injuries. Additionally, the study found that swimmers with reduced dorsiflexion had a higher incidence of muscle pain in the triceps surae and the plantar region, suggesting a direct relationship between joint limitation and overload discomfort, as noted by [PERSON] et al. [27]. Different studies have reported varying values regarding the contribution of kicking to swimming speed. While some authors indicate that the lower limbs can increase relative swimming speed by approximately 10% [28], other studies have suggested that, under specific testing conditions, kicking can contribute up to 31% to the improvement of total propulsion [21]. These differences may be attributed to the methodology used in each study, including measurement conditions and the swimming styles analyzed. We acknowledge that comparing with a group of non-swimmers could have helped differentiate which biomechanical characteristics are specific to swimmers compared to other athletes or the general population.