Changes in Adiposity, Muscular Strength, and Functional Capacity Following a National Holiday Break in Chilean Students with Intellectual Disabilities Attending Special-Education Schools

Background: National holiday breaks may involve less structured daily routines and cultural practices that favor excess energy intake, yet short-term changes in youth with intellectual disability (ID) following these breaks remain underexplored. This study examined changes in adiposity, muscular strength, and functional capacity following Chile’s national holiday break among students with ID. Methods: In this observational, single-group pre–post study, 49 students with mild-to-moderate ID (35 males, 14 females; 15.9 ± 4.0 years) were assessed before and after the holiday break. Anthropometric and adiposity indicators (body weight, waist [WC] and neck [NC] circumference, BMI, waist-to-height ratio [WHtR], submandibular skinfold [SS]), handgrip strength (absolute, relative) and functional capacity (countermovement jump, five-repetition sit-to-stand, timed up-and-go) were evaluated. Sex-differential changes were assessed using the time-by-sex interaction in mixed-model ANOVA, with Holm correction applied across outcomes within each domain. Within-sex pre–post comparisons were also adjusted using the Holm procedure. Results: No time-by-sex interaction remained significant after correction (all adjusted p ≥ 0.137). Significant time effects remained for SS (adjusted p = 0.012) and handgrip strength (adjusted p < 0.001), but not for NC. In secondary analyses, only the increase in SS (+15.6%; adjusted p = 0.025) and the increases in absolute (+8.0%) and relative (+7.6%) handgrip strength in males (both adjusted p = 0.002) remained significant. Changes in females were not statistically significant and were therefore interpreted descriptively (all adjusted p ≥ 0.31), and no significant changes in functional capacity were detected. Conclusions: The national holiday break was associated with a small increase in SS and an increase in handgrip strength, with the latter potentially reflecting a familiarization effect rather than a true physiological gain in strength. After correction for multiple comparisons, the findings do not support sex-specific conclusions; the observed pattern among females should therefore be considered hypothesis-generating and requires confirmation in larger, controlled studies.