Cardiorespiratory fitness and body mass index of Nigerian youth: A FitnessGram-based assessment

Abstract

BACKGROUND

The global decline in youth physical fitness and the concurrent rise in overweight and obesity have led to an increasing prevalence of non-communicable diseases, with low-income and middle-income countries disproportionately affected.

AIM

To determine the Healthy Fitness Zone (HFZ) achievement rates of Nigerian children and adolescents on the 20-meter shuttle run test and body mass index (BMI) using the FitnessGram criterion-referenced health standards.

METHODS

A cross-sectional study was conducted involving 3225 school-aged children and adolescents [boys (n = 1522); girls (n = 1703)], aged 9-16 years, from Benue State, Nigeria. Cardiorespiratory fitness (CRF) was assessed using the FitnessGram 20-meter shuttle run test, and converted to aerobic capacity (AC) values, while BMI served as a proxy for body fat. Sex and age differences in CRF and BMI were examined using factorial analysis of covariance. Participants’ HFZ achievement rates were determined based on FitnessGram standards.

RESULTS

The Healthy Fitness Zone achievement rates for AC were 82.7% for males and 78.7% for females. Younger children (9-11 years) exhibited higher compliance with CRF standards than older adolescents, a trend consistent across both sexes. Males consistently outperformed females in CRF. Regarding BMI, both sexes showed high achievement rates – 94.5% for males and 96.9% for females. Compared to Hungarian, European and American youth, Nigerian children and adolescents outperformed their international counterparts. In terms of BMI, Nigerian youth of both sexes outperformed their international peers.

CONCLUSION

Based on FitnessGram standards, Nigerian youth demonstrated favorable AC and body composition relative to international peers. Nevertheless, there were sex and age disparities in AC, with adolescent females and older males at greater risk of falling below health standards. Interventions promoting regular endurance-based physical activity are urgently needed to mitigate future cardiovascular disease risks.

Key Words: Exercise; Fitness testing; Nigerian youth; Physical fitness; Public health

Core Tip: This study assessed the proportion of Nigerian youth who met the FitnessGram criterion-referenced health standards for aerobic capacity (AC) and body composition. Achievement rates for AC were 82.7% among males and 78.7% among females. For body composition, both sexes showed high success rates – 94.5% for males and 96.9% for females. Compared with their American and European counterparts, Nigerian youth performed better on both health indicators. However, disparities were observed in AC, with older males and adolescent females more likely to fall short of the standards. Regular participation in aerobic physical activity is recommended to reduce future cardiovascular disease risk.

INTRODUCTION

The health-related physical fitness construct comprises three major components: (1) Cardiovascular endurance (CRE) (cardiorespiratory or aerobic fitness); (2) Body composition (BC); and (3) Musculoskeletal function[1]. While all three components are linked to health across the lifespan, cardiorespiratory fitness (CRF) and BC (fatness) are more closely associated with risk factors of cardiometabolic diseases than other fitness components in youth[2,3] and adult[4-6]. Epidemiological studies have consistently shown that fitness and fatness are both associated with the risk of metabolic syndrome and cardiovascular diseases in youth[2,7,8]. However, evidence also indicates that they have independent and interactive effects on health profiles[3,5].

Nigeria has the largest Black population in the world, yet studies examining the relationship between youth fitness and adult health are scarce. Limited available evidence comparing Nigerian youth with their American counterparts[9] indicates that Nigerian youth generally exhibit low levels of fitness, while rates of overweight and obesity are increasing[10]. Previous fitness assessments among Nigerian youth have focused primarily on normative comparisons based on age-specific and sex-specific percentiles[9]. However, such percentile-based evaluations do not address health-relevant questions such as, “how fit is fit enough” or “what level of fitness is required to gain health benefits”. A distinctive strength of the FitnessGram health-related fitness test is its use of criterion-referenced standards, which set cut-off scores indicative of desirable health outcomes for each test item.

The FitnessGram has become the most widely used physical fitness assessment tool for children and adolescents globally. Since its inception in 1992[11] and subsequent revisions, including the 2017 update[1], it has been used extensively to evaluate youth fitness across various populations. These assessments have compared youth performance against criterion-referenced standards to determine passing rates[12-16]. To date, no population-based study in Nigeria has evaluated youth fitness using FitnessGram standards for the progressive aerobic cardiovascular endurance run (PACER) - a measure of CRF and body mass index (BMI) - a proxy measure for body fatness. The present study addresses this gap by evaluating the proportion of Nigerian children and adolescents (herein referred to as youth) who meet the FitnessGram standards for PACER and BMI. Direct comparisons with other international studies are not possible due to differences in sampling and methods but comparisons are provided with available international datasets and international normative data to put the results in context with similar research.

MATERIALS AND METHODS

Participants

This cross-sectional study included a total of 3225 participants, comprising 1017 children (girls, n = 532; boys, n = 485) and 2208 adolescents (girls, n = 1171; boys, n = 1037), drawn from 21 schools (10 primary and 11 secondary) across the three senatorial districts of Benue State, Nigeria. Benue State is located in Nigeria’s North Central geopolitical zone, one of the country’s six geopolitical zones.

Sample size was calculated using Lorentz’s formula with a population greater than 10000[17], based on an estimated obesity prevalence of 2.3% from a previous study in the region[10]. A minimum sample size of 215 was required (with a 95%CI level and a 5% margin of error and a confidence limit of 1.96); however, the sample was increased to 3320 because of ease of access, to ensure representativeness, allow for subgroup analysis, and account for potential dropouts. The methodology highlighting the sampling procedure, inclusion criteria, and pilot testing has been previously described[18].

All participants were apparently healthy and had not taken part in any structured physical exercise program for at least six months prior to data collection. The study procedures and objectives were clearly explained, and written informed consent was obtained from parents or guardians, along with child assent. The research team visited each school twice. The first visit involved the measurement of physical characteristics and familiarization with the test protocols. The second visit was used to conduct the fitness testing. Ethical approval for the study was obtained from the Benue State University Health Research Ethics Committee (No. BSUTH/MKD/HREC/2013/017), and all procedures complied with the Declaration of Helsinki[19]. Data collection took place between 9:00 AM and 12:00 noon on each testing day, and all assessments were administered in the same order and by the same team members to ensure consistency.

Procedures

Anthropometric characteristics were measured following standardized procedures[20]. Participants were barefoot and minimally clothed. Body mass and height were measured indoors using an electronic digital scale (Seca Model 880, Birmingham, United Kingdom) and a wall-mounted stadiometer (Seca Model 206, United Kingdom). Measurements were taken to the nearest 0.1 kg for body mass and 0.1 cm for height. BMI was calculated as weight in kilograms divided by height in meters squared (kg/m²).

CRF was assessed using the 20-meter shuttle run test, also referred to as the PACER. This is a multistage, progressively intense test similar to a graded exercise test, and it is recognized as a valid and reliable measure of CRE in youth[21]. Detailed descriptions of the PACER protocol can be found elsewhere[18]. To allow comparisons with studies using the one-mile run or other endurance run performances, PACER lap scores were converted to peak VO₂ or AC using the FitnessGram regression equation, which incorporates age, BMI and PACER performance[1]. The prevalence of children and adolescents with ‘healthy’ CRF was estimated using sex-specific and age-specific FitnessGram criterion-referenced standards for peak VO₂.

To provide context on the results, descriptive comparisons of age and sex profiles are made with available data from United States[13], Hungary[16], and seven European countries [mean Healthy Fitness Zone (HFZ) achievement rates][22]. Additionally, aerobic capacity (AC) was compared with an international sample of 1142026 children and adolescents aged 10-17 years from 50 countries, tested between 1981 and 2014[23].

Statistical analysis

All data were analyzed using IBM SPSS Statistical software, version 20 (IBM Corporation, Armonk, NY, United States), with statistical significance set at P ≤ 0.05. The Kolmogorov-Smirnov test was used to assess data normality. Levene’s test of sphericity was used to test the homogeneity of variances to ensure the assumptions required for parametric testing were met. Descriptive statistics (mean ± SD) were computed for all measured and derived variables by sex and age (9-16 years). PASS (achieving HFZ)/FAIL (need improvement-health risk) classifications for each participant on PACER and BMI were based on the FitnessGram criterion-referenced health standards. The proportion and 95%CI of participants meeting these standards was calculated by age and sex. Comparisons with other international youth data were also made where available. Independent samples t-tests (or Mann-Whitney U tests where appropriate) were used to assess sex differences. Multivariate logistic regression models were conducted to examine odds ratios with respective 95%CI associated with meeting HFZ for BMI and CRE based on participants’ sex and age (9-11-children; 12-16-adolescents) groups. Additionally, a 2 × 3 [sex and age (9-11; 12-14; 15-16)] factorial analysis of covariance (ANCOVA) was conducted to examine age and sex differences in CRF and BMI. Post-hoc pair-wise comparisons were conducted using Bonferroni method. For hypothesis testing, the effect sizes (η²) were calculated to evaluate the magnitude of differences between groups; the criteria used to characterize a small, moderate, and large effect size were 0.20, 0.50, and 0.80, respectively[24].

RESULTS

Of the 3320 adolescents who met the eligibility criteria, data from 3225 participants were included in the statistical analysis. Data from 95 youth were excluded due to missing information, absenteeism, or non-compliance with study protocols, resulting in a participation rate of 97.1%. Descriptive data for PACER and BMI, along with passing rates by age and sex, are presented in Table 1. The FitnessGram criterion-referenced health standards (revised, 2017) used in this study are shown in Table 2.

Table 1 Participants’ descriptive data for the progressive aerobic cardiovascular endurance run and Body mass index (n = 3225).

	n	Progressive aerobic cardiovascular endurance run (mL/kg/minutes)			Body mass index (kg/m2)
		Mean	SD	%Pass (95%CI)	Mean	SD	%Pass (95%CI)
Age (boys)
9	126	47.1	16.9	95.2 (91.3-98.4)	17.4	3.3	95.2 (91.3-98.4)
10	161	46.6	14.4	93.2 (88.8-96.9)	18.2	3.1	88.8 (83.9-93.8)
11	198	46.4	16.1	90.9 (86.9-94.9)	18.3	4.4	96.0 (92.9-98.5)
12	276	45.9	14.7	86.6 (82.6-90.6)	18.5	3.7	94.6 (91.7-97.1)
13	265	44.7	17.1	80.8 (75.8-85.3)	18.7	3.6	95.5 (92.8-97.7)
14	244	43.6	15.9	73.3 (67.6-78.7)	19.5	3.9	97.1 (94.7-98.8)
15	155	43.9	17.8	71.0 (63.9-78.1)	19.5	4.2	95.5 (91.6-98.7)
16	97	43.1	19.5	68.1 (57.7-77.3)	19.5	4.1	88.7 (81.4-94.8)
Age (girls)
9	118	44.9	10.5	98.3 (95.8-100.0)	17.0	2.5	100.0 (100.0-100.0)
10	184	45.5	18.0	97.8 (95.7-99.5)	17.7	3.2	97.3 (94.6-99.5)
11	230	43.7	16.2	94.8 (91.7-97.4)	18.8	3.7	96.1 (93.5-98.3)
12	313	43.6	16.6	84.3 (80.2-88.5)	18.5	3.0	96.2 (93.9-98.1)
13	302	42.6	17.8	78.8 (74.2-83.1)	19.2	3.6	96.4 (94.0-98.3)
14	259	41.7	18.0	64.5 (58.7-70.3)	19.7	3.7	96.1 (93.8-98.5)
15	192	41.8	20.0	59.2 (52.4-66.5)	20.1	3.9	99.8 (98.4-100.0)
16	105	38.9	14.2	41.0 (31.4-50.5)	20.2	4.6	96.2 (92.4-99.0)

Table 2 FitnessGram criterion-reference standards for progressive aerobic cardiovascular endurance run and body mass index (2017 revised standards).

Age	Progressive aerobic cardiovascular endurance run (mL/kg/minutes)		Body mass index (kg/m2)
	Boys	Girls	Boys	Girls
9	-	-	18.9	19.4
10	40.2	40.2	19.7	20.3
11	40.2	40.2	20.5	21.2
12	40.3	40.1	21.3	22.1
13	41.1	39.7	22.2	22.9
14	42.5	39.4	23.0	23.6
15	43.6	39.1	23.7	24.3
16	44.1	38.9	24.5	24.8

The CRE HFZ achievement rate among males was 82.7% (68.1%-95.2%), generally higher than that of females at 78.7% (41.0%-98.3%). Among males, however, 16-year-olds fell short of the health standard. For BMI, males had a mean achievement rate of 94.5% (88.7.8%-97.1%), closely matching that of females at 96.9% (96.1%-100%). Compliance with BMI health standards was excellent in both sexes, with more than 92% of participants meeting the standard across all age groups. Detailed performance results for both fitness measures are presented in Table 1.

Descriptive patterns observed in the study are related to results from similar research in other countries to provide context for the relative level of health-related fitness reported here. Figure 1 compares the overall proportion of Nigerian youth meeting the health standards with available international data[13,16,22]. In CRE, Nigerian males outperformed their Hungarian, European and American peers by 15.7%, 19.9% and 26.8%, respectively, while Nigerian females exceeded their Hungarian, European and American counterparts by 24.7%, 30.6% and 36.1%, respectively. For BMI, Nigerian males and females surpassed Hungarian achievement rates by 24.0% and 20.3%, European achievement rates by 22.1% and 19.0% and American achievement rates by 38.0% and 39.3%, respectively.

Figure 1 Proportion of males and females in the Healthy Fitness Zone for progressive aerobic cardiovascular endurance run and body mass index by country. BMI: Body mass index; PACER: Progressive aerobic cardiovascular endurance run.

In comparison with international reference standards[23], Nigerian youth generally exceeded the AC thresholds (Figure 2). A notable exception was observed among males aged 13-16 years, whose performance fell below the standard. Overall, the international data showed that 67.0% of males and 54.0% of females achieved healthy levels of CRF, with a progressive decline in prevalence evident from age 10 onward[23]. Nigerian females consistently performed above the threshold at all age levels. Detailed results are illustrated in Figure 2.

Figure 2  Comparison of Healthy Fitness Zone achievement rates for aerobic capacity between Nigerian youth and the international sample of 1142026 from 50 countries.

Table 3 presents the odds ratios (OR) 95%CI for the associations of sex and age group with AC and BMI. Males were significantly less likely to achieve the HFZ for AC than females (OR = 1.87, 95%CI: 1.31-2.67; P = 0.001), whereas the age model was not significant (OR = 0.88, 95%CI: 0.58-1.32; P = 0.534). For BMI, males were less likely to meet the HFZ compared with females (OR = 0.82, 95%CI: 0.68-0.99; P = 0.042). Being an adolescent was associated with a 4.97 (95%CI: 3.63-6.81; P < 0.001) times greater likelihood of not meeting the HFZ for BMI compared with the younger age group.

Table 3 The odds of meeting Healthy Fitness Zone in aerobic capacity and body mass index.

Outcome variable	Predictor	Group	Odds ratio	95%CI	P value
Aerobic capacity	Age	Adolescent	1	0.58-1.32	0.534
		Child	0.88
	Sex	Male	1
		Female	1.87	1.31-2.67	0.001
Body mass index	Age	Adolescent	1
		Child	4.97	3.63-6.81	< 0.001
	Sex	Male	1
		Female	0.82	0.68-0.99	0.042

To assess the effects of sex and age on PACER performance and BMI, a 2 × 3 (sex × age) ANCOVA was conducted, with participants’ height and weight included as covariates to control for individual differences. For CRF performance, significant main effects were found for sex (F_{(1, 3217)} = 110.87, P < 0.001, η² = 0.033), with males performing significantly better than females and age (F_{(2, 3217)} = 85.09, P < 0.001, η² = 0.050), the younger age group performing better than the older age groups. The sex × age interaction was not significant (P = 0.603). Post-hoc analysis revealed that males consistently outperformed females, and males’ performance improved with age. Among females, performance improved linearly from ages 9 to 11 but became inconsistent thereafter.

For BMI, the 2 × 3 ANCOVA showed no significant main effect of sex (F_{(1, 3217)} = 0.813, P = 0.367), but a significant main effect of age (F_{(2, 3217)} = 46.79, P < 0.001, η² = 0.028). No significant sex × age interaction was observed (P = 0.081). Examination of BMI means indicated a linear increase with age in both sexes. Further analysis revealed that the younger age group performed significantly better than the older age groups.

DISCUSSION

The present study examined the fitness status of Nigerian children and adolescents using CRE, and BMI relative to the FitnessGram health standards and international reference values. Overall, the results demonstrated a high overall CRE levels and a healthy BMI prevalence in both sexes, though with notable sex-related and age-related variations in AC outcomes. The findings provide important insights into the fitness and health status of Nigerian youth, with implications for both public health and school-based interventions. There are challenges in making direct comparisons with results from other international studies of health-related fitness but the achievement rates of Nigerian youth are considerably higher when compared to values reported in previous research. The sections below put the results in context and summarize the value of the data for ongoing surveillance and programming in Nigeria.

AC performance

AC is considered to be perhaps the most important functional indicator of health-related fitness due to the strong links to other conditions. The FitnessGram HFZ standards are based on values that confer a reduced risk of metabolic syndrome and associated health conditions so it is a useful indicator of overall health status. The HFZ achievement rates of Nigerian youth on CRE (82.7% for males and 78.7% for females) were higher (respectively) than those reported for Hungarian youth (67% and 54%)[13], American youth (53.9% and 40.8%)[16], and European youth (62.8% and 48.1%)[22]. Findings from a meta-analysis involving 30 European countries, which reported average CRF performances of 78% for males and 83% for females, align with our results; however, the gender pattern is inconsistent with ours[25]. The higher levels of performance among Nigerian youth are consistent with findings from a systematic review that documented better performance among African youth on the 20-m shuttle run test compared to their peers from other continents[26].

The superior levels of HFZ in Nigerian youth for AC of 82.7% in males and 78.7% in females may reflect higher habitual levels of physical activity, active transport, and less processed diets – factors consistently shown to influence CRE in LMICs[27-29]. Nonetheless, the decline in AC among 16-year-old males is noteworthy. This age-related drop aligns with evidence of declining fitness during mid-to-late adolescence, particularly among males, possibly due to reduced physical activity participation, increased academic pressures, or early lifestyle transitions[2,30]. Additionally, this dip in performance among mid-adolescent males may reflect lifestyle and developmental transitions commonly associated with this age range, such as reduced engagement in spontaneous physical activity, or early adoption of sedentary behaviors linked to digital media use. Physiologically, puberty-related increases in body mass without proportional gains in activity levels or muscular efficiency could also contribute to the reduced AC performance observed[31].

Compared with international reference data (67.0% of males and 54.0% of females meeting healthy CRF levels)[23], the findings highlight a global decline in youth aerobic fitness, which the World Health Organization Regional Office for Africa[32] links to urbanization, motorized transport, and inadequate recreational spaces. Notably, Nigerian adolescents, especially females, show relatively better performance, possibly due to cultural or environmental factors that encourage greater daily activity. Nonetheless, the observed age-related decline in both Nigerian and global samples supports World Health Organization’s concern over decreasing physical activity from childhood to adolescence, underscoring the need for sustained school-based and community-based interventions aligned with World Health Organization regional strategies.

The ANCOVA results confirmed significant effects of sex on AC, with males consistently outperforming females, consistent with established physiological differences in hemoglobin concentration, muscle mass, and maximal oxygen uptake[31,33]. The inconsistent performance among females beyond age 11 may also be linked to sociocultural factors, including reduced participation in vigorous physical activity during adolescence due to gender norms or lack of supportive environments[28]. Similar trends have been reported in both developed and developing contexts, where girls’ fitness trajectories often plateau or decline earlier than boys’[31].

BMI performance

The HFZ standards for BMI reflect established international thresholds for overweight and obesity. The values are labelled as HFZ thresholds rather than ‘normal weight’ to focus attention on BMI as a health-related dimension of fitness rather than a weight indicator. The BMI achievement rates among Nigerian youth (94.5% for males and 96.9% for females) were also substantially higher than respective values reported for Hungarian youth (70.5% and 76.6%)[13], American youth (56.5% and 57.6%)[16], and European youth (72.4% and 77.9%)[22]. The higher BMI performance of Nigerian youth documents a lower prevalence of overweight and obesity compared to their Western peers. There are multiple factors contributing to overweight and obesity but it is likely that it stems from a more active lifestyle and healthier dietary pattern. Additionally, diets in Nigeria tend to include less processed and calorie-dense foods than those commonly consumed in Western countries[27].

With respect to BMI, the findings revealed very high compliance with health standards in both sexes (> 92%). This contrasts sharply with data from the United States, where fewer than 60% of adolescents fall within the healthy BMI range[16], and Europe, where prevalence of overweight and obesity continues to rise[34,35]. The low prevalence of unhealthy BMI in Nigerian adolescents likely reflects differences in dietary patterns, socioeconomic factors, and levels of habitual physical activity compared to high-income countries[10].

Age was the only significant factor influencing BMI, with a linear increase across adolescence. This trend is expected given normal growth and maturation, and aligns with findings from international growth studies[36]. The lack of a significant sex effect suggests that both Nigerian boys and girls share similar weight-status trajectories during adolescence, in contrast to some populations where sex differences in adiposity emerge strongly during puberty[13,16,37].

Although significant sex and age effects were observed for AC and Significant age effect for BMI, all effects were small based on Cohen’s guidelines[24]. This indicates that, despite statistical significance, the magnitude of these effects was limited. Thus, sex and age contributed minimally to variations in AC and BMI, suggesting that other factors such as training status, physical activity pattens, genetic disposition and lifestyle factors, exert stronger influences on these outcomes. Accordingly, the present findings should be interpreted with caution, as statistically significant differences may not necessarily reflect meaningful physiological or clinical variations.

Implications for national and international surveillance

Surveillance is a critical part of public health as it enables comparisons of data over time as well as benchmarking against other populations or countries. When benchmarked against international standards, Nigerian youth consistently performed above thresholds for AC, with the exception of 13-16 years old males. Nigerian males and females outperformed the international sample by 15.7% and 24.7%, respectively[23]. Compared with Hungarian and American peers, Nigerian adolescents demonstrated markedly superior fitness levels. These results corroborate earlier reports that youth in LMICs tend to exhibit higher CRE than those in more industrialized contexts, where sedentary lifestyles and obesogenic environments are more pervasive[33,38].

For BMI, Nigerian adolescents displayed healthier profiles than peers from Hungary, other European countries[22] and the United States. Given the rising global concern of childhood obesity[34], these findings highlight a relative protective advantage in Nigerian youth. However, the increasing urbanization and nutrition transition in sub-Saharan Africa may threaten this trend in the coming years. It is therefore important for public health and education stakeholders to initiate strategies such as structured physical activity programs and healthy nutrition to sustain this trajectory.

Nigerian youth outperform their Western peers in cardiorespiratory endurance and BMI, highlighting the influence of sociodemographic and environmental factors on physical fitness. These differences are largely attributed to lifestyle and developmental disparities between regions. In Nigeria and other LMICs, adolescents often engage in active transportation, household chores, and informal physical activities due to limited motorized transport and lower access to sedentary entertainment, fostering greater energy expenditure and cardiovascular fitness[28,29]. Additionally, lower rates of overweight and obesity among Nigerian adolescents may be linked to dietary habits featuring less processed and calorie-dense foods compared to Western diets high in fats and sugars[27].

Public health implications

The implications of these findings for cardiometabolic health are significant. CRF, as reflected in PACER performance, and healthy BC, as indicated by BMI, are both established predictors of long-term cardiometabolic risk in youth populations[39,40]. The relatively poor PACER performance of Nigerian girls compared to both their male peers and international standards suggests a potential vulnerability to future cardiometabolic complications, given that low CRF is associated with increased risks of obesity, hypertension, insulin resistance, and metabolic syndrome[41,42]. Conversely, the higher BMI passing rates observed across Nigerian youth are encouraging, as maintaining a healthy BC is protective against CMDs.

The molecular cytopathological effects of cardiorespiratory endurance and overweight/obesity on CMD of youth involve a complex interplay of metabolic, inflammatory, and cellular dysfunctions. For instance, CRF exerts protective molecular effects by enhancing mitochondrial function, endothelial function, and insulin sensitivity while reducing, oxidative stress, proinflammatory cytokines such as C-reactive protein, interleukin-6, and tumor necrosis factor-alpha – factors that collectively promote better cardiometabolic health[5,40]. The cytopathological effect of improved fitness includes enhanced smooth muscle relaxation and reduction in systemic inflammation and arterial stiffness[40]. Conversely, excessive fatness contributes to chronic diseases through endothelial dysfunction, chronic low-grade inflammation, oxidative stress, and overall metabolic dysregulation which are major drivers of CMD[43,44]. Therefore, the promotion of healthy lifestyle behaviors such as regular engagement in aerobic exercise, adherence to a healthy diet, and the adoption of effective weight-control practices among youth, should be considered a key public health priority for reducing CMD risk.

The findings from this study highlight several important implications for public health policy and practice. The relatively high fitness and healthy BMI observed among Nigerian children and adolescents provide an encouraging picture of youth health. However, necessary steps need to be taken to sustain and improve this trend. The superior cardiovascular fitness and BC observed among Nigerian adolescents can be explained by the Youth Fitness-Metabolic Risk Continuum model[43], which highlights the inverse relationship between CRF, healthy BC, and metabolic risk factors such as hypertension, dyslipidemia, and insulin resistance. This suggests that active Nigerian youth may have a lower cardiometabolic risk profile, offering long-term protection against noncommunicable diseases. These findings support Sustainable Development Goal 3 on Good Health and well-being, particularly target 3.4, which aims to reduce premature noncommunicable diseases mortality through prevention and health promotion. To sustain this advantage, policies should promote physical activity across schools, communities, and urban settings, institutionalize comprehensive physical education, and provide safe, inclusive environments for all children and adolescents. Integrating youth fitness monitoring into national health policies can help link surveillance to preventive interventions, reinforcing lifelong health consistent with the life-course vision of Sustainable Development Goal 3.

The findings from this study offer critical insights into sex-specific and age-specific determinants of fitness among Nigerian youth. Specifically, males were 1.9 times more likely to exhibit low AC compared to their female counterparts. Conversely, males were 0.82 times as likely to be at risk of overweight relative to females, whereas the likelihood of being at risk of overweight increased fivefold with age, particularly when comparing adolescents to younger children. These findings highlight the importance of sex-sensitive and age-sensitive interventions in promoting healthy physical development among Nigerian youth. The increased risk of low aerobic fitness among males calls for targeted physical activity programs emphasizing cardiovascular endurance, while the marked rise in overweight risk with age underscores the need for early preventive strategies to curb excess weight gain during adolescence. Implementing school-based and community-based fitness initiatives could play a pivotal role in improving overall youth health and reducing future CMD burden.

The observed sex-related and age-related disparities in AC warrant attention. Interventions should particularly target older male adolescents and post-pubertal females to sustain physical activity participation and fitness levels during this critical developmental stage. School-based programs promoting lifelong physical activity, alongside public health policies that preserve opportunities for active living, for example active transportation, and access to safe recreational spaces could be effective strategies. Although the BC levels are currently favorable, proactive strategies that prevent the onset of overweight and obesity in the context of Nigeria’s ongoing nutrition transition are needed.

The need to establish regular national fitness surveillance systems, similar to those in the United States, Europe and other developed countries in Nigeria is imperative. These systems would provide critical data for tracking changes in youth fitness and informing evidence-based interventions.

Study limitations

Findings from this study should be interpreted in the light of some limitations. The cross-sectional design precludes causal inferences about age-related changes in fitness and BMI. Longitudinal studies would provide stronger insights into developmental trajectories. Furthermore, the study did not account for contextual factors such as socioeconomic status, dietary patterns, or levels of habitual physical activity, which could help explain observed differences. The exclusive inclusion of in-school youth, excluding out-of-school youth, who may have different risk profiles is another limitation. This will limit generalizability of findings across broader youth population in Nigeria, and this may introduce sampling bias. This study was conducted in Benue State, one of the 36 states in Nigeria; therefore, the data are not nationally representative. A national population-based or multi-centre study would enhance generalizability.

However, several strengths of this study must be acknowledged. To our knowledge, this is the first study to evaluate youth HFZ achievement rates based on a FitnessGram assessment in African children and adolescents. Other studies only used FitnessGram test protocols to evaluate outcomes of interest. The large sample size, high participation rate, and the use of standardized, criterion-referenced health standards for fitness assessment are features that enhance the reliability and comparability of the findings.

CONCLUSION

Nigerian adolescents demonstrated encouragingly high levels of AC and healthy BMI relative to international peers. Nevertheless, the findings revealed sex-related and age-related disparities in AC, with adolescent females and older male adolescents at greater risk of falling below health standards. These results underscore the importance of targeted interventions and continuous surveillance to sustain and improve adolescent fitness in Nigeria. As the country undergoes rapid social and economic transitions, proactive strategies will be critical to safeguard youth health and prevent the rise of obesity and related non-communicable diseases. Future research should examine the factors driving variability in youth fitness patterns, while longitudinal studies are needed to clarify how CRF and BC contribute to CMD prevention among Nigerian children and adolescents.

ACKNOWLEDGEMENTS

The authors gratefully thank the principals, teachers and students of the participating schools for their cooperation during data collection. The authors also gratefully acknowledge the efforts of the research assistants who facilitated the data collection process.