A Longitudinal Cross-Sectional Analysis of Physical Fitness and Motor Competency for Intermediate School Students

ABSTRACT 

Background: The systematic assessment of physical fitness and motor skills, including fundamental coordination tasks like jump roping, is critical for monitoring health, development, and the foundational constructs of physical literacy in school-aged youth. Objective: This study aimed to conduct a cross-sectional analysis of fitness data across eight grade cohorts (Pre-K to Grade 8) to identify developmental and gender-related trends, with a specific focus on the diagnostic value of a 30-second jump rope test as a measure of coordination. Methods: A retrospective analysis was conducted on anonymized fitness test records from 146 students. Data included measures of flexibility, jump rope coordination, horizontal jump (H.J.), vertical jump (V.J.), 30-meter sprint, medicine ball throw (MB6), weight, and height. Descriptive statistics (Mean, SD), independent samples t-tests, and one-way ANOVA with post-hoc tests were used to analyze gender and grade-level differences. Results: Significant increases in performance were observed for power (H.J., V.J., MB6) and speed (30m) from early to later grades. Coordination, measured by jump rope skips in 30 seconds, showed a dramatic and variable increase, indicating it is a skill highly dependent on practice and instruction. Gender differences emerged prominently in middle school, with males generally demonstrating superior performance in power and speed tasks, while females showed more proficiency in coordination in several grade cohorts. Conclusion: The fitness test battery, particularly the jump rope coordination test, proved highly effective in tracing developmental trajectories and identifying skill-specific deficits. The results underscore the necessity of integrating regular, standardized motor assessment, including object-control coordination tasks, into the educational curriculum to foster physical literacy, promote lifelong physical activity, and identify at-risk students early.

Keywords: physical fitness, motor competency, physical literacy, jump rope, coordination, school-based assessment, developmental trajectories, gender differences

INTRODUCTION 

The declining levels of physical activity and concomitant rise in childhood obesity and related metabolic conditions represent a significant global public health challenge of the 21^st century (Guthold et al., 2020). In response, there has been a renewed and urgent focus on the role of educational institutions as primary settings for promoting physical health and fostering the concept of ‘physical literacy’. Physical literacy is holistically defined as motivation, confidence, physical competence, knowledge, and understanding to value and take responsibility for engagement in physical activities for life (Whitehead, 2019). Central to this multifaceted concept is the robust development of fundamental motor skills (FMS) -categorized as locomotors (e.g., running, jumping) and object-control (e.g., throwing, catching, striking) skills- which are the foundational building blocks for participation in sports, games, and an active lifestyle across the lifespan (Robinson et al., 2015).

The assessment of physical fitness in school settings has a long history, traditionally utilized to evaluate overall health status and identify athletic talent. However, contemporary perspectives, particularly those emerging between 2020 and 2025, increasingly emphasize its diagnostic value in gauging a child’s journey toward physical literacy (Edwards et al., 2023). While tests of muscular strength, power, speed, and flexibility provide objective data on a student’s physical capacity, measures of coordination offer unique insight into neuromuscular control and skill proficiency. The jump rope test, a classic assessment of coordination, rhythm, and cardiovascular endurance, requires the integration of visual tracking, timing, and bilateral coordination. Its utility in school-based assessments has been highlighted in recent literature as a practical and valid measure of motor competence (Drenowatz et al., 2021). When analyzed collectively and longitudinally, these data can reveal critical information about both typical and atypical developmental pathways, the efficacy of physical education (PE) curricula, and can highlight specific neuromuscular or conditional areas where students may require additional support or intervention (Cattuzzo et al., 2016).

Recent literature has further cemented the link between early motor competence, including coordination, and a spectrum of broader educational and health outcomes. Studies indicate that children with higher levels of motor competence are more likely to be physically active, exhibit better cardiorespiratory fitness, and maintain a healthier weight status (López-Gil et al., 2023). Furthermore, emerging evidence suggests a positive correlation between physical fitness components -particularly executive function- and cognitive performance, academic achievement, and psychosocial well-being in youth (Donnelly et al., 2024). This positions physical fitness and coordination assessment not as an isolated measure of athleticism, but as a key indicator of holistic child development, integral to the educational mission.

Despite this robust understanding, many school systems lack a systematic, longitudinal approach to fitness assessment, often overlooking specific coordination skills like jump roping in favor of more general fitness metrics. Analyzing a comprehensive cross-sectional dataset that spans multiple developmental stages, from early childhood through adolescence, can provide a powerful illustration of these developmental trends and articulate the immense value of such a longitudinal perspective, particularly for skill-based assessments.

This study presents a scientific analysis of a cross-sectional dataset encompassing students from Pre-Kindergarten (PPK) through Grade 8 (S2), with a specific focus on the jump rope coordination test. The primary aims are:

1. To describe and quantify the physical fitness and motor competency levels, with a detailed analysis of jump rope proficiency, across different school grades.
2. To analyze gender differences in fitness components, including coordination, within and across grade levels.
3. To identify key developmental trends and critical periods for motor skill development, particularly for coordinated jumping.
4. To discuss the implications of these findings for the promotion of physical literacy and the implementation of evidence-based assessment practices in educational settings, integrating recent (2020-2025) scholarly work.

METHODS 

Research Design and Data Source

This study employed a retrospective, cross-sectional analysis of existing anonymized physical fitness test records. The data were compiled from eight separate grade-level cohorts: PPK (Pre-K), K5 (Kindergarten), Grade 1, Grade 2/3, Grade 3/4, Grade 5/6, Grade 6, and Secondary (S1 & S2). The combined dataset included records for 146 students at Nm.Wr.Qs.

Participants

The sample consisted of 146 children and adolescents. A breakdown of the sample by grade and gender is presented in Table 1. Students’ gender distribution was relatively balanced across the entire sample, though some grade-level cohorts had small sample sizes, which is a noted limitation for sub-group analyses.

Grade Cohort	Male (n)	Female (n)	Total (n)
PPK	6	2	8
K5	9	5	14
Grade 1	7	5	12
Grade 2/3	5	6	11
Grade ¾	7	10	17
Grade 5/6	5	8	13
Grade 6	5	11	16
Secondary (S1/S2)	15	13	28
Total	59	60	119

Table 1: Sample Size and Gender Distribution by Grade Cohort

 *Note: Gender was not reported for 27 participants in the original S2 dataset; these were excluded from gender-specific analyses, hence the total for this table is 119.*

Measures and Variables

The following fitness components were assessed using standardized field tests, as recorded in the original data tables:

1. Flexibility (Flex.): Measured in centimeters using a sit-and-reach test. Positive values indicate reach beyond the toes.
2. Coordination (Coor.): Number of successful jump rope skips in a 30-second interval.
3. Lower-Body Power (Horizontal Jump – H.J.): Standing broad jump distance measured in centimeters.
4. Lower-Body Power (Vertical Jump – V.J.): Vertical jump height measured in centimeters.
5. Speed (30m): Time to sprint 30 meters, measured in seconds. All times were converted to seconds (e.g., 8″ 36 became 8.36 seconds).
6. Upper-Body Power (MB6 Lb.): Distance thrown for a 6-pound medicine ball, measured in centimeters.
7. Anthropometrics: Body weight (in pounds) and height (in centimeters). These were used to calculate Body Mass Index (BMI).

Data Analysis

All statistical analyses were conducted using IBM SPSS Statistics (Version 29). Data from the original tables were cleaned and standardized. Descriptive statistics (means and standard deviations) were calculated for all variables by grade and gender. To examine gender differences, independent samples t-tests were conducted within each grade cohort where sample size permitted (n>5 per group). A one-way Analysis of Variance (ANOVA) was used to test for significant differences in mean performance across grade levels for each fitness variable. Where the ANOVA was significant (p < .05), Tukey’s HSD post-hoc test was applied to identify which specific grade levels differed from one another. Effect sizes were calculated using Cohen’s d for t-tests (small: d=0.2, medium: d=0.5, large: d=0.8) and eta-squared (η²) for ANOVA (small: 0.01, medium: 0.06, large: 0.14). The alpha level for statistical significance was set at p < .05.

RESULTS

The results are presented in four sections: an overview of developmental trends across grades, a detailed analysis of gender differences, an examination of body composition, and a focused analysis of jump rope coordination.

Developmental Trends Across Grade Levels

A clear and statistically significant developmental trend was observed for all performance-based measures. As expected, as children grew older, their performance in tasks requiring power, speed, and strength improved markedly. Descriptive statistics for key variables across grades are presented in Table 2.

Grade	n	H.J. (cm) M (SD)	V.J. (cm) M (SD)	30m (s) M (SD)	MB6 (cm) M (SD)	Flex. (cm) M (SD)	Coor. (Jumps) M (SD)
PPK	8	89.4 (8.5)	9.0 (2.1)	8.76 (1.45)	93.8 (18.9)	+5.5 (4.8)	1.0 (1.6)
K5	14	103.9 (13.7)	12.6 (3.5)	7.01 (0.76)	108.6 (18.1)	+5.8 (4.1)	0.2 (0.4)
Gr 1	12	125.8 (15.2)	11.0 (3.1)	6.50 (0.83)	136.8 (16.9)	+4.8 (4.9)	9.3 (7.5)
Gr 2/3	11	124.1 (21.2)	16.7 (4.9)	6.22 (0.95)	166.4 (37.1)	+3.6 (8.6)	16.3 (7.8)
Gr 3/4	17	141.2 (25.8)	17.9 (5.1)	6.28 (0.75)	228.5 (40.8)	–4.4 (8.2)	21.5 (10.2)
Gr 5/6	13	141.2 (22.7)	16.5 (5.3)	6.05 (0.62)	218.1 (38.4)	+2.8 (7.8)	67.2 (48.1)
Gr 6	16	162.8 (16.3)	21.9 (5.1)	5.62 (0.47)	289.7 (65.8)	+1.9 (8.5)	27.6 (11.2)
Secondary	28	181.8 (29.1)	25.9 (8.8)	5.66 (0.84)	372.9 (78.9)	–1.9 (11.3)	30.5 (12.8)

Table 2: Descriptive Statistics (Mean and Standard Deviation) for Key Fitness Variables by Grade Level

One-way ANOVA revealed significant main effects for grade level on all performance variables: H.J. (F(7, 111) = 32.15, p < .001, η² = 0.67), V.J. (F(7, 111) = 21.44, p < .001, η² = 0.58), 30m sprint (F(7, 111) = 16.02, p < .001, η² = 0.51), and MB6 throw (F(7, 111) = 71.89, p < .001, η² = 0.82). Post-hoc analyses indicated that the most significant jumps in performance occurred between early elementary (PPK, K5) and later elementary grades (Gr 2/3, 3/4), and again between late elementary and secondary school.

Figure 1. Mean Horizontal Jump Distance by Grade Level

For upper-body power (MB6), the progression was even more dramatic, increasing by nearly 400% from the PPK to the Secondary cohort, highlighting the significant development of muscular strength through adolescence, particularly in males.

Flexibility showed a distinct pattern, with positive mean scores (indicating reach beyond toes) in early grades that declined, becoming negative on average in the Grade 3/4 and Secondary cohorts. This suggests a relative decrease in hamstring and lower back flexibility as children age, a common finding associated with growth spurts and reduced activity.

The Development of Jump Rope Coordination

The jump rope coordination scores presented a unique and highly informative non-linear trend (F(7, 111) = 15.89, p < .001, η² = 0.50). Performance was minimal in PPK (M=1.0, SD=1.6) and K5 (M=0.2, SD=0.4), indicating a near-universal inability to perform the skill in early childhood. A significant jump occurred in Grade 1 (M=9.3, SD=7.5), suggesting this period is a critical window for initial skill acquisition. Scores then showed a steady, significant increase through Grade 3/4 (M=21.5, SD=10.2).

A remarkable outlier was observed in the Grade 5/6 cohort, where the mean score skyrocketed to 67.2 jumps, albeit with an enormous standard deviation (SD=48.1). This indicates extreme variability within this group; while some students were highly proficient, others remained at a beginner level. This suggests that by this age, jump rope proficiency becomes highly dependent on specific practice and exposure outside of general physical development. Scores then consolidated in Grade 6 (M=27.6, SD=11.2) and Secondary (M=30.5, SD=12.8), showing less variability and indicating a stabilization of skill among those who have acquired it.

Gender Differences in Physical Performance

Gender differences were minimal in the earliest grades (PPK, K5) but became increasingly pronounced throughout elementary and middle school. Detailed comparisons for selected cohorts are presented in Table 3.

Grade & Variable	Males M (SD)	Females M (SD)	p-value	Cohen’s d
Grade 3/4 (n=7 / n=10)
H.J. (cm)	151.4 (33.9)	133.9 (17.1)	0.17	0.66
MB6 (cm)	247.1 (40.1)	215.6 (37.2)	0.10	0.81
Coordination (Jumps)	18.1 (8.2)	23.9 (10.9)	0.23	-0.60
Flexibility (cm)	-11.0 (6.5)	+0.3 (6.9)	0.002	-1.69
Grade 6 (n=5 / n=11)
H.J. (cm)	170.0 (8.9)	159.5 (17.8)	0.25	0.75
MB6 (cm)	290.0 (67.1)	289.5 (68.3)	0.99	0.01
Coordination (Jumps)	31.2 (15.5)	26.5 (9.7)	0.49	0.36
Secondary (n=15 / n=13)
H.J. (cm)	194.7 (26.3)	167.1 (23.8)	0.005	1.11
30m (s)	5.38 (0.72)	5.98 (0.83)	0.04	-0.78
MB6 (cm)	422.7 (71.5)	316.9 (38.7)	<0.001	1.86
Coordination (Jumps)	28.7 (13.1)	32.5 (12.4)	0.42	-0.30

Table 3: Gender Comparisons (Mean, SD, and p-value) for Selected Grade Cohorts

As shown in Table 3, by the secondary school level, males significantly outperformed females in the Horizontal Jump (p = .005, d = 1.11), the 30m Sprint (p = .04, d = -0.78), and the Medicine Ball Throw (p < .001, d = 1.86), representing medium to very large effect sizes. While not always statistically significant in smaller cohorts, the trend of males demonstrating superior performance in strength and power tasks was consistent from Grade 3/4 onward.

In contrast, no significant gender differences were found in jump rope coordination at any grade level, though the effect sizes in Grade 3/4 (d = -0.60) and Secondary (d = -0.30) suggested a trend favoring females, while in Grade 6, the trend slightly favored males (d = 0.36). This indicates that coordination, as measured by this task, is not gender-dimorphic in the way strength and power are, and proficiency is likely more linked to opportunity and practice. Females maintained a significant advantage in flexibility in Grade 3/4 (p = .002, d = -1.69), though this difference was no longer significant by secondary school.

Body Composition Trends

Height and weight increased predictably with age. The Body Mass Index (BMI) was calculated and converted to kg/m² for analysis. Mean BMI percentiles, estimated based on CDC growth charts, generally fell within the healthy range for most cohorts. However, individual cases of very high BMI (>95th percentile) were present, particularly in the Grade 3/4 (e.g., Participant ZMP: BMI ~31) and Grade 6 (e.g., Participant KW: BMI ~33) cohorts, aligning with national concerns about childhood obesity. These outliers often corresponded with notably poor performance in weight-bearing fitness tasks like the 30m sprint and horizontal jump, as well as very low jump rope scores, demonstrating the impact of body composition on motor skill performance.

DISCUSSION

This cross-sectional analysis provides a compelling snapshot of the physical development of students from early childhood through late adolescence, with particular insight into the development of coordination through jump roping. The results largely align with established motor development literature and offer several key, actionable insights for promoting physical literacy in educational settings, viewed through the lens of recent research.

The Jump Rope as a Diagnostic Tool for Physical Literacy

The jump rope coordination data provide perhaps the most vivid illustration of the difference between physical growth and skill acquisition. The near-zero scores in PPK and K5 are expected, as jump roping is a complex skill requiring bilateral coordination, rhythm, and timing that typically emerges around age 6 or 7 (Haywood & Getchell, 2020). The significant jump in Grade 1 marks a critical sensitive period for introducing this skill. The dramatic spike and high variability in the Grade 5/6 cohort are highly informative. This pattern suggests that by ages 10-12, mere physical maturation is insufficient to develop proficiency. Instead, performance becomes heavily influenced by factors such as deliberate practice, participation in sports or activities that incorporate jump roping, and cultural or social exposure to the activity (Drenowatz et al., 2021). The subsequent consolidation of scores in later grades suggests a proficiency barrier (Stodden et al., 2008) has been crossed by some, while others may have disengaged from the skill entirely.

This has direct implications for physical literacy. A child who cannot jump rope may be excluded from playground games and certain physical activities, negatively impacting their confidence and motivation, key affective domains of physical literacy (Whitehead, 2019). Therefore, the jump rope test is not merely a measure of coordination; it is a powerful diagnostic for identifying students who are missing fundamental, culturally relevant movement skills that can facilitate social inclusion and ongoing participation.

Interpreting Broader Developmental Trajectories

The observed, statistically significant improvements in power, speed, and strength are consistent with normal physiological growth and maturation (Malina et al., 2004). The steep improvements in lower-body power (H.J., V.J.) and speed (30m) during the elementary years correspond to a critical period for developing fundamental movement skills (FMS). As Robinson et al. (2015) argue, proficiency in FMS is a primary mechanism underlying physical literacy. The dramatic increase in upper-body power (MB6), particularly in males during adolescence, can be attributed to the surge in testosterone and the development of greater muscle mass (Lloyd et al., 2014).

The significant decline in average flexibility is a concerning trend that has been documented elsewhere and is linked to increased sedentary behavior (e.g., screen time) and a lack of targeted stretching (Schranz et al., 2020). This highlights a specific, often overlooked, area for intervention within a physical literacy framework.

Addressing the Emergent Gender Gap and Skill Equity

The emergence of a significant gender gap in adolescence in strength and power tasks with large effect sizes is a well-established phenomenon (Thomas et al., 2022). While biological factors play a role, sociocultural factors are also at play. Research indicates that adolescent girls often experience a decline in physical self-perception and participation in strength-based activities (Barnett et al., 2022). Our findings suggest that the middle school years represent a critical window for implementing targeted, inclusive strength-building programs for girls (Behringer et al., 2024).

The lack of a significant gender gap in jump rope proficiency is a crucial finding. It demonstrates that when skills are equally practiced and valued for all children, performance gaps need not emerge. This reinforces the importance of a curriculum that explicitly teaches and provides ample practice for a wide range of motor skills to all students, regardless of gender.

CONCLUSION 

This comprehensive analysis of multi-grade fitness data vividly illustrates the dynamic nature of physical development throughout the school years. The results confirm expected trends of improving power and speed, highlight a critical period of declining flexibility, and reveal a pronounced gender gap in strength-related tasks emerging in adolescence. The in-depth analysis of jump rope coordination provides a powerful testament to the role of practice and instruction in motor skill development, separate from mere physical maturation. This skill-based assessment proved to be a highly sensitive diagnostic tool for identifying variability in motor competence and potential gaps in physical literacy. By moving beyond mere data collection to data-informed action, educators and policymakers can create more effective, inclusive, and developmentally appropriate physical education programs. Such programs, which explicitly teach foundational skills like jump roping to all children, are fundamental to empowering them with the competence, confidence, and desire to lead active, healthy lives, thereby fulfilling the core promise of physical literacy.

LIMITATIONS AND FUTURE RESEARCH

This study has several limitations. Its cross-sectional design infers longitudinal trends from different individuals at single time points; a true longitudinal study would provide more robust data on individual developmental pathways. The sample sizes for some grade-level cohorts were small, limiting the statistical power of some gender comparisons. Future research should employ longitudinal designs with larger samples, track the relationship between early jump rope proficiency and later physical activity levels, and incorporate qualitative measures of students’ confidence and enjoyment in performing these skills.

APPLICATIONS IN SPORT

The data strongly supports the integration of systematic fitness and skill assessment as a core component of a physical literacy-informed curriculum. As Edwards et al. (2023) argue, assessment should not be for grading but for guiding. The results of such tests can:

1. Identify Skill Deficits Early: The jump rope test can flag students in Grade 1 who are not acquiring fundamental coordination skills, allowing for early intervention.
2. Inform Instruction: Physical educators can use these data to form small groups for targeted skill instruction (e.g., a jump rope clinic for the low-performing students in Grade 5/6) and to ensure their curriculum addresses flexibility and upper-body strength for girls.
3. Promote a Mastery Climate: By focusing on individual improvement in skills like jump roping, rather than solely on athletic performance, teachers can foster the confidence and motivation that are central to physical literacy (Robinson & Goodway, 2021).