Reference Values for Physical Functional Performance Across Childhood, Adolescence, and Early Adulthood in Individuals with Intellectual Disabilities

Abstract

Individuals with Intellectual Disabilities (ID) often exhibit reduced physical fitness, leading to early declines in the ability to perform daily activities. This study aimed to characterize and establish reference values for physical functional performance by sex and age group in school-aged children with ID. A total of 321 participants (ages 5–26 years) from special education schools were assessed. Physical functional performance was measured using the 4 × 10 m shuttle run (4 × 10 m), Timed Up and Go (TUG), Five-Repetition Sit-to-Stand Test (5R-STS), and Countermovement Jump (CMJ). Two-way ANOVA, Kruskal–Wallis tests, and percentile values (5th–95th) were calculated by sex and age group. Males consistently demonstrated higher performance than females. Cross-sectional comparisons showed higher 4 × 10 m, TUG, and 5R-STS performance during adolescence in both sexes, while CMJ performance was higher in males during early adulthood. Adolescents outperformed children in 4 × 10 m, TUG, and CMJ tests (p < 0.05). Females exhibited lower 4 × 10 m and CMJ performance in early adulthood compared with adolescence (p < 0.05), whereas males showed no significant differences across these stages. Physical functional performance in individuals with ID varied according to sex and age, with males generally demonstrating better performance. Adolescence is associated with higher performance, while females experience reductions in lower-limb power in early adulthood. These findings highlight sex- and age-related differences and support the need for targeted monitoring and intervention strategies in this population.

1. Introduction

Individuals with Intellectual Disability (ID) present neurodevelopmental deficits characterized by limitations in intellectual functioning and adaptive behavior, with onset during the developmental period and typically identified in childhood or adolescence [1]. Beyond these core characteristics, individuals with ID often exhibit more complex health profiles and marked health disparities, including a higher prevalence of comorbid conditions such as metabolic and cardiovascular disorders, which can have lifelong consequences [2]. Additionally, people with ID tend to engage in lower levels of physical activity, display higher sedentary behavior, and reduced muscular strength compared with peers without disabilities, factors that contribute to an increased risk of chronic disease development [3,4,5,6]. Such inequalities and risk profiles have been consistently associated with reduced life expectancy relative to the general population, underscoring the importance of understanding how key health-related variables differ across distinct stages of life in this population [7].

Consequently, persistently low physical activity and high sedentary behaviors contribute to increased adiposity [8], musculoskeletal [9] and cardiovascular dysfunctions [10], all of which are strongly associated with declines in functional performance. Physical functional performance refers to the set of physical abilities required to independently perform activities of daily living, including endurance, muscular strength, and aerobic capacity [11]. Physical fitness, a key determinant of functional performance, declines with age, with sedentary behavior accelerating losses in aerobic capacity and muscular strength and contributing to the earlier onset of functional frailty [11,12]. In contrast, regular physical activity and higher levels of physical fitness are strongly associated with enhanced functional capacity and daily physical performance, underscoring the central role of physical fitness in preserving and improving functional abilities across diverse populations [13]. Within this context, sex-related differences in physical functional performance have been reported, with women consistently exhibiting lower levels of performance than men [14]. Despite these differences, overall both males and females with ID fail to reach the minimum handgrip strength thresholds associated with sarcopenia risk, presenting values even lower than those reported in older adults at risk of frailty [15]. Moreover, muscular strength in individuals with ID is markedly reduced compared with peers without ID [16]. Therefore, the assessment of muscular strength should be considered a priority screening measure, given its close association with functional capacity, fall risk, and the loss of coordinative abilities [17].

A range of field-based tests has been proposed to assess the physical functional performance in individuals with ID, several of which are suitable for use across different stages of development. Commonly used measures include the Five-Repetition Sit-to-Stand Test (5R-STS) for muscle power [18], handgrip strength for muscle strength [19,20], the Timed Up and Go test (TUG) for functional mobility [21], the countermovement jump (CMJ) for lower-limb power [22], and the 4 × 10 m shuttle run test (4 × 10 m) for speed and agility [20,23]. These tests capture complementary aspects of functional performance and are interrelated, with potential utility as indicators of overall functional capacity in individuals with ID [24]. However, despite their widespread use, evidence describing how performance in these tests varies according to sex and age remains limited, particularly across childhood, adolescence, and early adulthood. Existing reference data are scarce and are largely derived from adult populations with ID [15,25,26]. Therefore, the aim of this study was to characterize and establish reference values for physical functional performance by sex and age group in school-aged children with ID.

2. Materials and Methods

2.1. Study Design and Sample

This study formed part of the larger “Ludoinclusion^®” project involving individuals with ID, conducted by the University of Santiago. A quantitative, descriptive, and cross-sectional design was employed to examine sex and age-related differences in functional capacity. Given that the primary aim of this study was to establish sex- and age-specific normative reference values for physical functional performance, sample adequacy was evaluated based on the precision and stability of the estimates rather than on traditional hypothesis-driven power calculations.

The final sample comprised 321 participants distributed across sex and age groups, with subgroup sizes ranging from 20 to 88 individuals, which supports the generation of stable percentile distributions (p5–p95) and reliable mean estimates for the physical functional performance tests. To contextualize the exploratory comparative analyses by sex and age group, prior evidence in individuals with ID reporting small-to-moderate differences in functional performance was considered, indicating that the available sample is adequate for detecting meaningful group differences without relying on extreme effect size assumptions.

The sample consisted of 321 participants, who were divided by sex (male–female) and age group (children [5–11 years], adolescents [12–17 years], and early adulthood [18–26 years]). Participants were selected by convenience sampling from eight special educational institutions in Santiago, Chile. Parents and/or legal guardians provided informed consent authorizing students’ participation in this study. The research followed the guidelines of the Declaration of Helsinki for research involving human subjects [27] and was approved by a University Ethics Committee (code 2052/CEIH/2021).

Inclusion criteria comprised students with a diagnosis of mild to moderate intellectual impairment defined by an intelligence quotient (IQ) of 50–70 (mild) or 35–49 (moderate) [28], as assessed using the Wechsler Intelligence Scale for Children, WISC-III [29], or the Wechsler Adult Intelligence Scale, WAIS-IV [30], provided by the psychologist of each educational institution. Additional criteria included enrollment in a special education center; regular participation in physical education classes (at least 90 min per week); age between 5 and 26 years; completion of at least one of the four defined physical functional tests, independent mobility; and a valid medical health certificate. Exclusion criteria were severe to profound ID (IQ < 35) [28], use of canes or crutches, wheelchair dependence, incomplete functional test data, and/or school disengagement. Overall, 45 students were excluded from the initial sample of 366 for not meeting the inclusion criteria.

2.2. Procedure

Data were collected between April 2022 and 2024 at the institutions affiliated with the project. After obtaining authorization from eight special education schools, meetings were held with tutors and school staff to explain the study objectives and assessment protocols. Written informed consent was obtained from parents or legal guardians prior to participation, ensuring voluntary and anonymous involvement, with the option of withdrawing at any time. Assessments were conducted during scheduled morning and afternoon sessions, with each student accompanied by a tutor if needed. Anthropometric measurements included body weight, height, body mass index (BMI), and waist circumference. Physical functional performance was assessed using the 4 × 10 m, TUG, 5R-STS, and CMJ tests.

2.2.1. Anthropometric Measures

Body weight (kg) and height (m) were measured using a digital scale integrated with a stadiometer (SECA Model 769^®, Hamburg, Germany). BMI (kg/m²) was calculated from these measurements, and waist circumference (cm) was assessed using a non-elastic metal measuring tape (CESCORF^®, Porto Alegre, Rio Grande do Sul, Brazil) [24].

2.2.2. Physical Functional Performance

Physical functional performance was assessed through field-based tests evaluating muscle power, functional mobility, and agility (Figure 1). All participants were familiarized with the testing protocols during prior physical education sessions at their respective institutions. Before testing, a standardized 5 min warm-up consisting of joint mobility exercises, light jogging, and vertical jumps was performed.

4 × 10 m Shuttle Run Test (4 × 10 m)

The test required participants to cover a total distance of 40 m, divided into four 10 m shuttle segments between two parallel lines marked 10 m apart, in the shortest possible time. An evaluator (A) was positioned at the starting line and another evaluator (B) at the opposite line. Participants were instructed to touch the evaluator’s hand at each turn. Time was recorded by evaluator A using a stopwatch, with results noted in seconds to the nearest hundredth [23]. Two trials were performed, and the mean time was used for analysis.

Timed Up and Go (TUG)

The test began with the participant seated on a chair without armrests, with the back against the backrest and feet flat on the floor. On the evaluator’s signal, the participant stood up and walked as quickly as possible to a marker placed 3 m ahead, turned around it, and returned to the seated position. Participants were encouraged to complete the circuit at their maximum safe speed. Time to completion was recorded by the evaluator. Two trials were performed, and the mean time was used for analysis [31,32].

Five-Repetition Sit-to-Stand Test (5R-STS)

Participants started in a seated position on a chair with their feet flat on the floor and arms crossed over the chest. The test consisted of performing five consecutive sit-to-stand repetitions as quickly as possible. A familiarization trial was first conducted, during which participants practiced the movement sequence. Two timed trials were then performed, with completion time recorded for analysis [18].

Countermovement Jump (CMJ)

Participants performed a countermovement jump while standing on the platform, with hands placed on their hips, and were instructed to jump as high as possible following the evaluator’s demonstration [33]. Jump height (cm) was measured using a contact platform (Chronojump^®, Barcelona, Spain). The mean jump height from the two remaining trials was used for analysis [24].

2.3. Statistical Analysis

Data distribution was assessed using the Kolmogorov–Smirnov test. Descriptive statistics are presented as mean, standard deviation (SD), and percent delta (Δ%) for anthropometric variables (body weight, height, BMI, and waist circumference), as well as for physical functional performance measures (4 × 10 m, TUG, 5R-STS, and CMJ), stratified by sex (male and female) and age group (children, adolescents, and early adulthood). Between-group comparisons according to sex and age group were performed using two-way analysis of variance (ANOVA) for normally distributed variables. When significant main effects or interactions were identified, Tukey’s post hoc test was applied to locate pairwise differences. For non-normally distributed variables, the Kruskal–Wallis test was used, followed by Bonferroni-adjusted post hoc comparisons. Physical functional performance outcomes assessed using the 4 × 10 m, TUG, 5R-STS, and CMJ tests are additionally presented as percentiles (p5, p10, p25, p50, p75, p90, and p95). One-factor analyses were conducted within each sex and age-group stratum. For each physical functional test, percentile values were calculated using only participants with valid test results, and interpretations were adjusted accordingly, following previously published methods [15]. All statistical analyses were conducted using SPSS software version 27 (SPSS Inc., IBM Corp., Armonk, NY, USA). The significance level was set at p < 0.05.

3. Results

The sample comprised 321 schoolchildren with ID, of whom 219 were males (68.2%). Among males, 25.1% were children, 43.3% adolescents, and 31.6% were in early adulthood. Among females, 25.5% were children, 44.1% adolescents, and 30.4% were in early adulthood. Anthropometric characteristics stratified by sex and age group are presented in

Table 1. Sex- and age-specific anthropometric characteristics in school-aged children with ID.

	Males				Females
	Total (N = 219)	Children (n = 55)	Adolescents (n = 95)	Early Adults (n = 69)	Total (N = 102)	Children (n = 26)	Adolescents (n = 45)	Early Adults (n = 31)	p Value
Age (years)	15.34 (5.46)	8.85 (1.91)	14.42 (1.51)	21.99 (3.10)	15.30 (5.35)	8.79 (1.85)	14.73 (1.52)	21.71 (3.07)	<0.001 a*
Body weight (kg)	60.37 (22.70)	38.35 (14.61)	63.95 (18.93)	73.43 (20.18)	57.98 (22.59)	36.83 (15.00)	65.28 (19.37)	66.35 (20.72)	<0.001 b*
Height (m)	1.57 (0.17)	1.35 (0.14)	1.63 (0.12)	1.65 (0.08)	1.51 (0.15)	1.34 (0.16)	1.59 (0.10)	1.54 (0.09)	<0.001 a*
BMI (kg/m2)	23.60 (6.18)	20.32 (4.98)	23.34 (5.41)	26.63 (6.68)	24.82 (7.53)	19.74 (4.42)	25.58 (5.49)	28.05 (9.66)	<0.001 a*
Waist Circumference (cm)	81.38 (15.61)	71.47 (12.94)	82.37 (15.46)	88.11 (13.80)	80.99 (16.06)	71.01 (12.30)	82.05 (13.46)	88.17 (18.21)	<0.001 a*

n = Sample size. BMI = Body mass index. Data are presented as mean and SD. * = Significance p < 0.05 by a = Kruskal–Wallis; ANOVA two-way b differences by sex between children, adolescents, and early adulthood.

. All anthropometric variables differed significantly according to sex and age group (p < 0.05).

Figure 2 illustrates physical functional performance across four tests (A) 4 × 10 m, (B) TUG, (C) 5R-STS, and (D) CMJ, stratified by sex and age group. For the 4 × 10 m agility test, significant effects of sex and age group were observed (p < 0.001). In males, agility performance improved from childhood to adolescence [↓ 3.79 (s); ↓ 24.06 (Δ%); p = 0.02], followed by a decline from adolescence to early adulthood [↑ 2.37 (s); ↑ 15.05 (Δ%); p = 0.01]. Females also showed significant improvements from childhood to adolescence [↓ 1.78 (s); ↓ 9.62 (Δ%); p < 0.001], with no significant changes thereafter [↑ 1.44 (s); ↑ 7.78 (Δ%); p = 0.45]. Significant sex-related differences in the 4 × 10 m test were observed during adolescence [2.75 (s); 17.78 (Δ%); p < 0.001] and early adulthood [1.82 (s); 10.10 (Δ%); p = 0.01], favoring males.

For the TUG test, significant sex and age group effects were also observed (p < 0.001). In males, mobility performance improved from childhood to adolescence [↓ 2.66 (s); ↓ 43.75 (Δ%); p < 0.001], with no further changes into early adulthood [↑ 0.01 (s); ↑ 0.16 (Δ%); p = 0.79]. Similarly, females showed significant improvements from childhood to adolescence [↓ 4.28 (s); ↓ 40.57 (Δ%); p < 0.001], but no significant changes were found between adolescence and early adulthood [↑ 0.61 (s); ↑ 9.73 (Δ%); p = 0.57]. A significant sex difference was detected in early adulthood [0.79 (s); 12.97 (Δ%); p = 0.03], with better performance in males.

In the 5R-STS test, no significant main effects of sex or age group were found (p = 0.359). Nevertheless, both sexes exhibited comparable trajectories, with improvements from childhood to adolescence ([males: ↓ 0.54 s; ↓ 5.56 (Δ%); p = 0.54]; [females: ↓ 0.71 s; ↓ 7.25(Δ%); p = 0.67]) followed by a decline from adolescence to early adulthood ([males: ↑ 0.95 s; ↑ 9.79 (Δ%); p = 0.38]; [females: ↑ 0.94 s; ↑ 9.60 (Δ%); p = 0.44]). No significant sex-related differences were observed across age groups.

In the CMJ test, significant changes were observed as a function of sex and age group (p < 0.001). In males, jump height increased from childhood to adolescence [↑ 5.96 (cm); ↑ 51.30 (Δ%); p < 0.001], with no significant changes from adolescence to early adulthood [↑ 0.07 (cm); ↑ 0.39 (Δ%); p = 0.89]. In females, jump height also increased from childhood to adolescence [↑ 3.44 (cm); ↑ 36.40 (Δ%); p < 0.001], followed by a significant decline from adolescence to early adulthood [↓ 4.40 (cm); ↓ 51.90 (Δ%); p < 0.001]. Significant sex differences were observed during adolescence [4.67 (cm); 36.27 (Δ%); p < 0.001] and early adulthood [9.14 (cm); 107.70 (Δ%); p < 0.001], with higher values in males.

Table 2. Sex- and age-specific percentile reference values for physical functional performance in school-aged children with ID.

Physical Functional Performance Tests
4 × 10 m (s) Males (N = 183)
	n	p5	p10	p25	p50	p75	p90	p95
Children	46	36.35	27.77	22.87	18.17	14.95	13.46	10.38
Adolescents	80	28.66	25.79	18.54	14.37	11.72	8.10	7.20
Early Adulthood	57	45.46	36.68	18.56	14.34	13.04	11.38	10.95
4 × 10 m (s) Females (N = 88)
	n	p5	p10	p25	p50	p75	p90	p95
Children	21	36.29	31.64	25.97	19.86	16.66	10.44	5.61
Adolescents	39	38.78	32.20	20.95	16.60	14.39	7.66	6.60
Early Adulthood	28	36.00	25.52	23.46	18.51	15.46	14.60	13.51
TUG (s) Males (N = 203)
	n	p5	p10	p25	p50	p75	p90	p95
Children	46	23.55	20.39	9.81	6.60	4.81	4.04	3.39
Adolescents	88	14.78	9.32	6.66	4.87	4.07	3.45	3.20
Adults	69	11.32	8.46	7.11	5.50	4.42	3.90	3.47
TUG (s) Females (N = 92)
	n	p5	p10	p25	p50	p75	p90	p95
Children	22	30.77	17.79	14.97	8.24	5.84	4.70	3.93
Adolescents	43	10.93	10.47	7.30	5.21	4.18	3.73	3.59
Early Adulthood	27	10.91	10.03	8.53	6.22	5.12	4,37	4.08
5R-STS (s) Males (N = 201)
	n	p5	p10	p25	p50	p75	p90	p95
Children	46	24.23	18.93	12.16	8.36	6.35	4.57	4.02
Adolescents	88	15.97	14.79	11.54	8.91	6.58	5.89	5.49
Early Adulthood	67	24.73	16.28	11.57	9.53	7.37	5.93	5.13
5R-STS (s) Females (N = 93)
	n	p5	p10	p25	p50	p75	p90	p95
Children	23	26.09	17.20	12.36	8.86	6.69	5.14	4.95
Adolescents	43	18.39	14.52	11.49	9.19	7.31	6.05	5.25
Early Adulthood	27	20.12	17.17	13.07	10.17	8.12	6.17	5.14
CMJ (cm) Males (N = 163)
	n	p5	p10	p25	p50	p75	p90	p95
Children	34	2.66	3.37	7.33	10.95	16.83	18.88	21.97
Adolescents	81	5.08	5.81	11.07	15.70	24.17	30.91	32.18
Early Adulthood	48	5.70	7.60	12.79	16.77	21.79	27.75	29.77
CMJ (cm) Females (N = 80)
	n	p5	p10	p25	p50	p75	p90	p95
Children	20	2.54	3.02	4.32	9.75	13.64	16.46	21.17
Adolescents	38	2.69	5.08	7.75	12.10	16.46	21.22	22.89
Early Adulthood	22	1.38	1.85	2.99	7.28	11.85	18.71	22.86

n = Sample size; 4 × 10 m = 4 × 10 m agility test; TUG = Timed up and go; 5R-STS = Five-repetition sit-to-stand test; CMJ = Countermovement jump. p5 = Lowest functional performance; p95 = Highest functional performance.

presents percentile distributions (p5–p95) for physical functional performance tests, stratified by sex and age group, providing reference values for functional performance across childhood, adolescence, and early adulthood in individuals with ID. For the 4 × 10 m, TUG, and 5R-STS tests, lower times indicate better performance, whereas in the CMJ test, higher values reflect greater jump height.

4. Discussion

The present study aimed to characterize and establish reference values for physical functional performance in school-aged individuals with ID, considering sex and age group. Overall, males demonstrated higher functional performance than females across all assessed measurement tests. For both sexes, cross-sectional patterns suggest higher performance in the 4 × 10 m, TUG, and 5R-STS tests during adolescence, whereas higher CMJ performance is observed in early adulthood among males only. Physical functional performance improved markedly from childhood to adolescence in the 4 × 10 m, TUG, and CMJ tests for both sexes. However, a divergent pattern emerged thereafter, with females showing a significant decline in CMJ performance from adolescence to early adulthood, while male performance remained stable across these stages.

Functional capacity refers to the physical abilities required to perform activities of daily living, including endurance, muscular strength, and aerobic capacity, which tend to decline with age, particularly among sedentary individuals. It is understood as a multidimensional construct integrating physical, mental, and social components [34]. Within the physical domain, various tests have been used to assess physical functional performance including handgrip strength [35], the 4 × 10 m agility test [36], the 30 s chair sit-to-stand test [37], the TUG test [38], and the Senior Fitness Test battery [39]. In general, higher functional performance is associated with healthier body composition and a lower risk of cardiovascular disease and metabolic syndrome, whereas poor performance is linked to increased frailty and mortality risk in individuals with ID [40,41]. In the population with ID, multiple tests have been used and adapted to assess physical functional performance; however, many of these instruments were originally designed for populations with different characteristics, resulting in a limited availability of validated tests with population-specific reference values. Among the validated assessments are the handgrip strength test [24,42], the modified 6 min walk test [43], the Tinetti Balance Assessment [44], and the 10 m incremental walk test [5].

Regarding performance in the 4 × 10 m test, cross-sectional comparisons showed higher performance in both males and females during adolescence, with mean times of 15.75 and 18.50 s, respectively. Despite this common developmental pattern, males consistently outperformed females, indicating a clear sex-related difference in agility performance. These findings are consistent with previous evidence, as Mendoza-Puelma et al. [24] reported a comparable mean time of 16.79 s in adolescents with ID. Overall, these results suggest that adolescence may be a critical period characterized by higher agility performance, while also highlighting persistent sex-related disparities observed during this stage. Additionally, functional performance in the 4 × 10 m test has been positively associated with both absolute and relative handgrip strength across children, adolescents, and adults, as well as with absolute handgrip strength asymmetry during adolescence, highlighting the interdependence between agility and muscular strength throughout development.

The TUG test is widely used in older adults and has also been applied to assess physical functional performance in individuals with ID. The test has been validated in populations with disabilities [38] and is commonly included in fitness assessment batteries for adults with ID [3]. In line with previous evidence, reported reference values for adolescents with Down syndrome (5.61 s) [45] are comparable to the mean TUG times observed in the present study, both in adolescent males (6.08 s) and females (6.27 s), supporting the external validity of our findings across ID populations. In the present study, women in early adulthood exhibited higher TUG times (mean: 6.88 s) than their adolescent counterparts and males of the same age group, indicating an emerging sex-related difference in functional mobility. Although these values do not exceed the >10 s threshold commonly used to indicate mobility impairment in older adults, even modest increases in TUG performance time have been associated with a higher risk of falls [46,47,48]. Taken together, these results suggest that individuals with ID—particularly women—may exhibit lower levels of functional mobility, consistent with patterns reported in the literature on premature functional aging.

Lower-limb strength in individuals with ID has commonly been assessed using the 30 s chair sit-to-stand test [49]. However, because this test requires sustained attention over a fixed period, recent studies have suggested the use of the 5R-STS test as an alternative for individuals with ID [18], as it evaluates the same movement pattern within a shorter and more manageable time frame [50]. Reference values for adults without ID under 60 years of age indicate mean 5R-STS times of 5.60 s in men and 5.76 s in women [51]. In contrast, adults with ID exhibit substantially longer completion times (10.65 s in men and 10.73 s in women), reflecting a reduction in physical functional performance of more than 100% compared with the general population. In the present study, 5R-STS performance differed across age groups, with higher performance observed during adolescence and lower performance in early adulthood in both sexes, in line with the study aim of examining age-related differences in physical functional performance. Notably, no significant sex differences were observed in 5R-STS performance, suggesting that lower-limb strength limitations are similarly expressed in males and females with ID across developmental stages. Furthermore, the 5R-STS values observed in adults with ID are comparable to those reported in older adults at risk of falls [52]. This resemblance underscores the presence of early functional decline in individuals with ID and reinforces the relevance of monitoring age-related changes in lower-limb strength from childhood through early adulthood, as proposed in the present study.

The CMJ has been used to assess physical fitness [22] and has been validated in para-karate athletes with ID [53]. Available evidence indicates that children with ID achieve lower jump height and power in the CMJ compared with individuals without disabilities [54]. Previous studies have shown that children with ID achieve lower jump height and power than their peers without disabilities, likely due to reduced voluntary muscle activation [16] and altered vertical jump kinematics [54]. In the present study, distinct age-related patterns in CMJ performance were observed, with both sexes showing higher performance from childhood to adolescence. However, lower CMJ performance was evident in females from adolescence to early adulthood [↓ 4.40 cm; ↓ 51.90%], whereas male performance remained stable across these stages. This divergence highlights a clear age-by-sex interaction in lower-limb power, suggesting that early adulthood may represent a critical period for the onset of functional decline in females with ID. These findings are consistent with previous research [14], which has reported greater vulnerability to premature functional deterioration in females with ID compared with males. Evidence from previous studies indicates that higher BMI negatively affects motor coordination [55], particularly in females, in whom it is associated with less favorable body-related perceptions and lower engagement in physical activity from adolescence to early adulthood. Although this evidence is derived from the general population, these factors may also be relevant in individuals with ID and could partially explain the observed sex-related differences in physical fitness and functional capacity [56].

Among the main limitations of the present study are its cross-sectional design, convenience sampling, and the omission of relevant factors such as the different syndromes associated with ID, medication use, habitual physical activity levels, socioeconomic context, and family lifestyle patterns, factors that may potentially influence physical functional performance. In addition, no complementary clinical assessments or analyses of biological maturation were included, which would have allowed for a more comprehensive understanding of developmental physical performance in this population.

The strengths of the study are that it represents the first investigation in a country in the southern part of the world to comprehensively describe sex- and age-related patterns of physical functional performance in schoolchildren with ID. Furthermore, the study provides a local normative framework that may guide evaluation, monitoring, and exercise prescription processes in educational and healthcare settings. The findings are valuable for professionals in the fields of education, health, and physical activity, as they enable the quantification of changes in physical functional performance in response to physical exercise interventions, curricular adaptations, modifications to the school environment, and family dynamics.

5. Conclusions

In schoolchildren with ID, physical functional performance assessed through the 4 × 10 m, TUG, 5R-STS, and CMJ tests demonstrates a differentiated pattern according to sex and age group. Overall, males exhibit superior performance compared to females. The highest levels of physical functional performance in both sexes are generally observed during adolescence; however, while females show a decline in CMJ performance when transitioning into adulthood, males demonstrate an improvement in the 4 × 10 m test during the same period. The sex- and age-specific functional patterns identified in this study provide clinically and educationally relevant insight into developmental trajectories of physical functional performance in individuals with ID. These findings may inform monitoring strategies, support evidence-based decision-making, and guide the development of targeted physical activity and exercise interventions aimed at preserving physical functional performance across key stages of development in this population.