# Limitations in Maximum Intensity Front Crawl in Swimmers with Down Syndrome
## 4 Discussion  
The aim of this study was to evaluate several biomechanics and bioenergetics features of maximum intensity front crawl in swimmers with Down Syndrome (SDS) and compare them with those of competitive swimmers of the same age and weekly training volume. Regarding the anthropometric characteristics of the athletes enrolled (Table 1), we observed that the swimmers in the SDS group, as expected from previous literature data, had significantly lower body masses and heights than the CNT athletes did [21]. In contrast, the BMI calculated in our DS swimmers did not indicate overweight values. These findings suggest that chronic training volume positively influenced the body composition of adult DS athletes in the present study, confirming previous data [5; 22; 23]. From a functional perspective, this study did not directly evaluate any specific strength component. However, the typical deficit in voluntary muscle strength in individuals with DS is already well-known and documented in the scientific literature (see [PERSON] et al. for a recent review on grip strength in DS patients [24]). The presumed strength deficit, along with the significant height deficit and consequently shorter upper limbs, likely contributed to the differences in the biomechanical and chronometric characteristics of maximum-intensity front crawl swimming between the two groups. Indeed, the lap times and stroke counts were significantly higher in both lengths for the SDS group, indicating lower propulsive forces and a biomechanical disadvantage for this group. At present, discriminating which biomechanical or kinematic factors are the most relevant for generating lower swimming speeds in athletes with DS is difficult, and this topic deserves further study. Furthermore, the horizontal body position in water may have played a relevant role in the propulsion biomechanics of individuals with DS. The body pitch was significantly greater in the SDS group's 0-25 m and 25-50 m lengths, with no interaction between length and group (Table 3). This could be attributed to two main factors: a lower propulsive capacity of the lower limbs in DS swimmers, who are unable to maintain the longitudinal axis in a horizontal position, leading to decreased buoyancy, and a lower ability of the abdominal muscles to maintain trunk alignment with a reduced inclination relative to the water surface [14]. In addition, motor dysfunctions (asymmetries, rhythm discontinuity, breathing pattern) due to the nature of the syndrome may also have affected the body position while swimming. We compared body pitch with lap times in both groups to further  
Figure 3: Relationships, estimated through simple linear regression analysis, between the angle of inclination relative to the plane (body pitch) of the water and the lap time, separately for the first (0–25 m, panel (**a**)) and second length (25–50 m, panel (**b**)) of the 50 m swimming test. Black squares: CNT group; white circles: SDS group. examine whether the trunk inclination could have impacted swimming propulsion. We found they were positively correlated, but only at 0-25 m in the SDS group, meaning that higher angles corresponded to slower times. The high linear regression coefficient indicated an association greater than 60% between the angle of inclination in water and lap time in SDS athletes. Notably, the body pitch remains greater at 25-50 m for the swimmers in the SDS group and remains low for those in the CNT swimmer group. However, interestingly, the relationship between the angle and swimming speed was lost entirely at 25-50 m for the SDS group. This may suggest that those swimmers with DS who can maintain a low body pitch at 0-25 m through more efficient propulsion also lose this ability at 25-50 m. Indeed, the associations among arm propulsive forces, lower limb kicking action, and pitch angle remain rather elusive in swimming.