Edited by: Marie Leiner, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, United States
Reviewed by: Adán Dagnino-Acosta, University of Colima, Mexico; Daniel Rossignol, Rossignol Medical Center, United States
This article was submitted to Child Health and Human Development, a section of the journal Frontiers in Public Health
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This study investigated current obesity prevalence and associations between musculoskeletal fitness test scores and the odds of being underweight, overweight, or obese compared to having a healthy weight in elementary school children in Corpus Christi, Texas. The sample analyzed consisted of 492 public elementary school children between kindergarten and fifth grade. Their ages ranged from 5 to 11 years. Trunk lift, 90° push-up, curl-up, and back saver sit and reach tests were administered. Weight status was determined using BMI scores and the CDC growth charts. Obesity prevalence remains high among elementary school-aged children in Corpus Christi, Texas. Higher 90° push-up test scores were most consistently associated with decreased odds of being obese as compared to being overweight and having healthy weight except in kindergarten. Conversely, higher trunk lift test scores were associated with increased odds of being obese in second and fourth grades. When children achieved the minimum score to be classified in the Healthy Fitness Zone, those with healthy weight had similarly low musculoskeletal fitness (i.e., abdominal strength and endurance, hamstring flexibility, and trunk extensor strength and flexibility) as peers with overweight and obesity, especially in the lower grades. It was concluded that increased obesity prevalence in higher grades may be precipitated (at least in part) by low musculoskeletal fitness in the lower grades, especially kindergarten. Given previous associations in the literature, low musculoskeletal fitness may be symptomatic of poor motor skill competence in the current sample. These findings suggest a need for early and focused school-based interventions that leverage both known and novel strategies to combat pediatric obesity in Corpus Christi.
Overweight and obesity remains a national priority and a pervasive trend in South Texas. Claims data from Blue Cross and Blue Shield of Texas show high incidence of diabetes with chronic conditions, e.g., chronic kidney disease, in South Texas, including a 107% increase in diabetes in 2016 (
Obesity is considered a chronic disease resulting from excessive fat accumulation and body mass (
In light of the astounding health- and cost-related impact of obesity (
When optimal, measures of health-related physical fitness are thought to enhance and extend physical activity experience (
Although the foregoing musculoskeletal fitness measures have been validated and are widely adopted (
The aims of the current study were to: (i) investigate whether muscle strength, endurance, and flexibility (i.e., trunk lift, 90° push-up, curl-up, and back saver sit reach test scores) are significantly associated with the odds of being overweight or obese compared to having a healthy weight in elementary school children, (ii) explore relative percentages of children who achieve HFZ classification as a function of weight status across each elementary school grade, and (iii) provide a cross sectional representation of current overweight and obesity prevalence in elementary school-aged children in Corpus Christi, Texas.
Data were collected from a cross section of 492 public elementary school children in kindergarten, first, second, third, fourth, and fifth grades. Their ages ranged from 5 to 11 years (Table
Descriptive and anthropometric data.
Kindergarten | 39 | 28 | 5.55 ± 0.5 | 1.13 ± 0.05 | 21.42 ± 4.35 |
1st Grade | 49 | 31 | 6.60 ± 0.58 | 1.19 ± 0.05 | 24.41 ± 5.95 |
2nd Grade | 30 | 41 | 7.67 ± 0.62 | 1.25 ± 0.07 | 28.16 ± 7.65 |
3rd Grade | 43 | 40 | 8.79 ± 0.57 | 1.31 ± 0.18 | 35.29 ± 12.12 |
4th Grade | 42 | 28 | 9.63 ± 0.68 | 1.36 ± 0.25 | 47.46 ± 25.87 |
5th Grade | 38 | 30 | 10.95 ± 0.71 | 1.42 ± 0.19 | 44.91 ± 16.44 |
A missing field was defined as the absence/omission of an entry for age, weight, height, and actual musculoskeletal fitness test scores, i.e., trunk lift, push-up, curl-up, and back saver sit and reach. Table
Respective protocols and equipment for trunk lift, push-up, curl-up, and the back saver sit and reach test were implemented as previously described in the FitnessGram® test administration manual (
Participants with any missing data were excluded: one data set was excluded in kindergarten, three were excluded in first grade, 12 were excluded in second grade, three were excluded in third grade, 16 were excluded in fourth grade, and 24 were excluded in fifth grade. Height and weight data were converted from inches and pounds to meters and kilograms, respectively. BMI was computed as the quotient of weight (kg) and the square of height (m). These scores were standardized as z-scores and used to determine respective percentiles for age and sex according to the Centers for Disease Control and Prevention (CDC) growth charts (
Data normality was explored using the Shapiro-Wilk significance value on Kolmogorov-Smirnov test of normality. All data were explored for outliers using box plots. Pearson's correlations were calculated to evaluate associations between students' scores on trunk lift, push-ups, curl-ups, and the back saver sit and reach test. This allowed the determination of multicollinearity. A series of multinomial logistic regression analyses were implemented to estimate odd ratios (ORs) and 95% confidence intervals for kindergarten through fifth grade. The healthy weight group was the referent category when exploring odds of being overweight or obese compared to having a healthy weight. A second set of multinomial logistic regression analyses were then implemented switching the referent category to the obese group, in order to explore the odds of being overweight compared to being obese. Although each grade level was analyzed individually, grades were also combined, in order to help account for any effects of sample size on confidence level. Third, fourth, and fifth grades were combined due to increased prevalence of obesity in these grades. Similarly, kindergarten, first, and second grades were combined. Finally, all grade levels were combined, and the same associations were explored. Sex and age were input as covariates in the statistical models, when grades were combined. The magnitudes of associations were presented as ORs and 95% confidence intervals (CIs). Significant two-tailed tests were set at 5% (i.e.,
Thirteen percent of the original 496 data sets was excluded due to missing data field(s). Therefore, 432 (87%) of the original data were deemed intact. The characteristics of the sample considered intact are presented in Table
Mean (SD) musculoskeletal fitness scores in:
The prevalence of overweight in kindergarten, first, second, third, fourth, and fifth grades was 17.6, 8.8, 20.3, 18.1, 11.4, and 17.7%, respectively (Table
Prevalence of each weight category in kindergarten through fifth grade.
Kindergarten | 67 | 17.64 | 17.64 | 60.30 | 4.41 |
1st Grade | 80 | 26.30 | 8.80 | 58.80 | 6.30 |
2nd Grade | 71 | 18.92 | 20.27 | 43.24 | 4.05 |
3rd Grade | 83 | 37.30 | 18.10 | 42.20 | 2.40 |
4th Grade | 70 | 55.70 | 11.40 | 30.00 | 2.90 |
5th Grade | 62 | 33.82 | 17.65 | 45.59 | 2.94 |
There were no significant, i.e.,
Fitness associations in kindergarten (reference group: healthy weight).
Overweight | Trunk lift | 0.197 | 1.372 | (0.849, 2.218) |
Push-ups | 0.797 | 1.050 | (0.725, 1.521) | |
Curl-ups | 0.270 | 0.748 | (0.446, 1.253) | |
Sit and Reach | 0.160 | 0.677 | (0.393, 1.167) | |
Obese | Trunk lift | 0.102 | 1.482 | (0.925, 2.374) |
Push-ups | 0.557 | 0.881 | (0.576, 1.346) | |
Curl-ups | 0.522 | 1.106 | (0.813, 1.504) | |
Sit and Reach | 0.166 | 0.691 | (0.410, 1.165) |
Associations between musculoskeletal fitness and weight status in kindergarten (reference group: obese).
Overweight | Trunk Lift | 0.778 | 0.926 | (0.541, 1.585) |
Push-ups | 0.500 | 1.192 | (0.716, 1.986) | |
Curl-ups | 0.172 | 0.676 | (0.386, 1.186) | |
Sit and Reach | 0.952 | 0.980 | (0.504, 1.906) |
The only significant associations in first grade were between push-ups (
Associations between musculoskeletal fitness and weight status in first grade (reference group: healthy weight).
Overweight | Trunk lift | 0.741 | 0.923 | (0.575, 1.483) |
Push-ups | 0.648 | 0.943 | (0.731, 1.215) | |
Curl-ups | 0.420 | 1.116 | (0.855, 1.458) | |
Sit and Reach | 0.761 | 0.935 | (0.606, 1.442) | |
Obese | Trunk lift | 0.350 | 0.915 | (0.760, 1.102) |
Push-ups |
0.002 | 0.641 | (0.483, 0.850) | |
Curl-ups | 0.305 | 1.112 | (0.908, 1.361) | |
Sit and Reach | 0.096 | 0.743 | (0.523, 1.055) |
Associations between musculoskeletal fitness and weight status in first grade (reference group: obese).
Overweight | Trunk Lift | 0.974 | 1.008 | (0.614, 1.657) |
Push-ups |
0.032 | 1.470 | (1.034, 2.090) | |
Curl-ups | 0.979 | 1.004 | (0.740, 1.361) | |
Sit and Reach | 0.372 | 1.259 | (0.759, 2.088) |
In second grade, there was a significant association between trunk lift (
Associations between musculoskeletal fitness and weight status in second grade (reference group: healthy weight).
Overweight | Trunk lift | 0.637 | 0.868 | (0.481, 1.565) |
Push-ups | 0.482 | 1.072 | (0.883, 1.302) | |
Curl-ups | 0.224 | 0.893 | (0.744, 1.072) | |
Sit and Reach | 0.250 | 1.312 | (0.826, 2.084) | |
Obese | Trunk lift |
0.016 | 2.151 | (1.156, 4.001) |
Push-ups | 0.167 | 0.807 | (0.595, 1.094) | |
Curl-ups | 0.715 | 0.962 | (0.784, 1.181) | |
Sit and Reach | 0.100 | 0.653 | (0.393, 1.086) |
Associations between musculoskeletal fitness and weight status in second grade (reference group: obese).
Overweight | Trunk Lift |
0.019 | 0.398 | (0.184, 0.862) |
Push-ups | 0.085 | 0.960 | (0.963, 1.865) | |
Curl-ups | 0.527 | 0.723 | (0.752, 1.181) | |
Sit and Reach |
0.024 | 2.049 | (1.100, 3.817) |
There was a significant association between push-ups (
Associations between musculoskeletal fitness and weight status in third grade (reference group: healthy weight).
Overweight | Trunk lift | 0.246 | 1.249 | (0.858, 1.817) |
Push-ups | 0.552 | 0.955 | (0.821, 1.111) | |
Curl-ups | 0.835 | 0.991 | (0.912, 1.077) | |
Sit and Reach | 0.284 | 1.210 | (0.854, 1.714) | |
Obese | Trunk lift | 0.100 | 1.374 | (0.941, 2.005) |
Push-ups |
0.000 | 0.719 | (0.597, 0.866) | |
Curl-ups | 0.177 | 0.953 | (0.888, 1.022) | |
Sit and Reach | 0.112 | 0.725 | (0.488, 1.078) |
Associations between musculoskeletal fitness and weight status in third grade (reference group: obese).
Overweight | Trunk Lift | 0.664 | 0.909 | (0.591, 1.399) |
Push-ups |
0.007 | 1.329 | (1.080, 1.635) | |
Curl-ups | 0.407 | 1.040 | (0.948, 1.142) | |
Sit and Reach |
0.029 | 1.668 | (1.055, 2.637) |
The only significant associations in fourth grade were between trunk lift (
Associations between musculoskeletal fitness and weight status in fourth grade (reference group: healthy weight).
Overweight | Trunk lift | 0.699 | 1.091 | (0.702, 1.695) |
Push-ups | 0.676 | 0.964 | (0.813, 1.144) | |
Curl-ups | 0.262 | 0.934 | (0.830, 1.052) | |
Sit and Reach | 0.204 | 0.794 | (0.556, 1.133) | |
Obese | Trunk lift |
0.016 | 1.480 | (1.077, 2.033) |
Push-ups | 0.108 | 0.904 | (0.799, 1.022) | |
Curl-ups | 0.299 | 0.956 | (0.879, 1.040) | |
Sit and Reach | 0.108 | 0.804 | (0.617, 1.049) |
Associations between musculoskeletal fitness and weight status in fourth grade (reference group: obese).
Overweight | Trunk Lift | 0.139 | 0.737 | (0.492, 1.104) |
Push-ups | 0.442 | 1.067 | (0.905, 1.257) | |
Curl-ups | 0.673 | 0.977 | (0.877, 1.089) | |
Sit and Reach | 0.934 | 0.987 | (0.727, 1.341) |
The only significant associations in fifth grade were between push-ups (
Associations between musculoskeletal fitness and weight status in fifth grade (reference group: healthy weight).
Overweight | Trunk lift | 0.641 | 1.094 | (0.749, 1.599) |
Push-ups | 0.499 | 0.944 | (0.800, 1.115) | |
Curl-ups | 0.491 | 0.967 | (0.879, 1.064) | |
Sit and Reach | 0.155 | 1.311 | (0.903, 1.905) | |
Obese | Trunk lift | 0.225 | 1.279 | (0.859, 1.904) |
Push-ups |
0.003 | 0.722 | (0.583, 0.894) | |
Curl-ups | 0.572 | 0.975 | (0.891, 1.066) | |
Sit and Reach | 0.620 | 0.921 | (0.664, 1.276) |
Associations between musculoskeletal fitness and weight status in fifth grade (reference group: obese).
Overweight | Trunk Lift | 0.493 | 0.855 | (0.547, 1.337) |
Push-ups |
0.023 | 1.307 | (1.038, 1.647) | |
Curl-ups | 0.886 | 0.992 | (0.894, 1.101) | |
Sit and Reach | 0.097 | 1.424 | (0.938, 2.163) |
When third, fourth, and fifth grades were combined (
Associations between musculoskeletal fitness and weight status in third through fifth grades (reference group: healthy weight).
Overweight | Trunk lift | 0.146 | 1.185 | (0.943, 1.488) |
Push-ups | 0.305 | 0.952 | (0.867, 1.046) | |
Curl-ups | 0.255 | 0.967 | (0.913, 1.024) | |
Sit and Reach | 0.359 | 1.099 | (0.899, 1.343) | |
Obese | Trunk lift |
0.006 | 1.319 | (1.082, 1.606) |
Push-ups |
0.000 | 0.832 | (0.762, 0.908) | |
Curl-ups | 0.278 | 0.976 | (0.934, 1.020) | |
Sit and Reach | 0.151 | 0.883 | (0.745, 1.047) |
Associations between musculoskeletal fitness and weight status in third through fifth grades (reference group: obese).
Overweight | Trunk Lift | 0.360 | 0.898 | (0.714, 1.130) |
Push-ups |
0.010 | 1.145 | (1.033, 1.269) | |
Curl-ups | 0.762 | 0.991 | (0.936, 1.050) | |
Sit and Reach |
0.037 | 1.244 | (1.013, 1.527) |
There was a significant association between trunk lift (
The odds of being overweight as compared to being obese increased by 24% for every unit increase in the sit and reach score (Table
When kindergarten, first, and second grades were combined (
Associations between musculoskeletal fitness and weight status in kindergarten through second grades (reference group: healthy weight).
Overweight | Trunk lift | 0.694 | 0.969 | (0.831, 1.131) |
Push-ups | 0.992 | 0.999 | (0.877, 1.139) | |
Curl-ups | 0.635 | 0.972 | (0.866, 1.092) | |
Sit and Reach | 0.825 | 0.974 | (0.772, 1.230) | |
Obese | Trunk lift | 0.536 | 0.976 | (0.904, 1.054) |
Push-ups |
0.001 | 0.764 | (0.650, 0.899) | |
Curl-ups | 0.346 | 1.055 | (0.944, 1.180) | |
Sit and Reach |
0.029 | 0.786 | (0.633,0.975) |
Associations between musculoskeletal fitness and weight status in kindergarten through second grades (reference group: obese).
Overweight | Trunk Lift | 0.933 | 0.993 | (0.845, 1.167) |
Push-ups |
0.006 | 1.308 | (1.080, 1.583) | |
Curl-ups | 0.263 | 0.921 | (0.798, 1.063) | |
Sit and Reach | 0.129 | 1.239 | (0.939, 1.636) |
There was a significant association between sit and reach and being obese (
When kindergarten through fifth grades were combined (
Associations between musculoskeletal fitness and weight status in kindergarten through fifth grades (reference group: healthy weight).
Overweight | Trunk lift | 0.326 | 1.078 | (0.928, 1.253) |
Push-ups | 0.524 | 0.978 | (0.913, 1.047) | |
Curl-ups | 0.857 | 0.996 | (0.953, 1.041) | |
Sit and Reach | 0.678 | 1.030 | (0.896, 1.184) | |
Obese | Trunk lift |
0.009 | 1.179 | (1.042, 1.335) |
Push-ups |
0.000 | 0.845 | (0.791, 0.904) | |
Curl-ups | 0.234 | 1.022 | (0.986, 1.059) | |
Sit and Reach |
0.001 | 0.826 | (0.736,0.926) |
Associations between musculoskeletal fitness and weight status in kindergarten through fifth grades (reference group: obese).
Overweight | Trunk Lift | 0.272 | 0.914 | (0.780, 1.073) |
Push-ups |
0.001 | 1.157 | (1.064, 1.257) | |
Curl-ups | 0.290 | 0.975 | (0.929, 1.022) | |
Sit and Reach |
0.004 | 1.248 | (1.072, 1.452) |
There was a significant association between trunk lift (
There was a significant association between sit and reach and being obese (
This study investigated associations between musculoskeletal fitness scores, i.e., muscle strength, endurance, and flexibility, assessed using trunk lift, 90° push-up, curl-up, and back saver sit and reach, and weight status, in elementary school children in Corpus Christi, Texas. The mean obesity prevalence, across all six grades, of 31.6% observed in the current study, exceeds the previously reported national average of 17.7% among children aged 6–11 years (
The lack of associations in kindergarten, first, third, and fifth grades, and the observed pattern of associations in second and fourth grades between trunk lift test scores and the odds of belonging to specific weight categories suggest a pervasive trend: children with overweight and obesity fared just as well or scored higher than peers with healthy weight in some grade levels. Those with overweight did not fare better than those with obesity. Children with obesity had higher trunk lift test scores than those with healthy weight in second and fourth grades (Figures
FitnessGram® standards require scores between 6–12 inches in children aged 5–9 years (i.e., Kindergarten through third grade) and 9–12 inches in children aged 10–12 years (i.e., fourth through fifth grade), in order to achieve HFZ on the trunk lift test. Although upwards of 85% of students achieved HFZ on the trunk lift test across all grades and weight categories except fifth grade (Table
Percentage of children who achieved Healthy Fitness Zone scoring in all grades.
Healthy weight | 95 | 39 | 61 | 96 |
Overweight | 100 | 46 | 55 | 100 |
Obese | 100 | 41 | 83 | 92 |
Healthy weight | 89 | 72 | 68 | 94 |
Overweight | 100 | 57 | 86 | 100 |
Obese | 86 | 19 | 67 | 86 |
Healthy weight | 95 | 39 | 61 | 96 |
Overweight | 100 | 46 | 55 | 100 |
Obese | 100 | 42 | 83 | 92 |
Healthy weight | 97 | 69 | 80 | 97 |
Overweight | 100 | 75 | 62 | 100 |
Obese | 100 | 16 | 35 | 74 |
Healthy weight | 96 | 82 | 87 | 96 |
Overweight | 100 | 60 | 60 | 90 |
Obese | 88 | 49 | 71 | 75 |
Healthy weight | 52 | 81 | 78 | 84 |
Overweight | 67 | 67 | 67 | 92 |
Obese | 65 | 18 | 39 | 63 |
Each unit increase in push-up test scores was associated with decreased odds of being obese in first, third, and fifth grades compared to being overweight and having healthy weight. This finding persisted when the different grade levels were combined This suggests that both the children with healthy weight and overweight fared better than those with obesity in these grades. FitnessGram® standards require scores between 3–8, 4–10, 5–13, 6–15, 7–15 repetitions for children aged 5–6, 7, 8, 9, and 10–11 years, respectively, in order to achieve HFZ on the 90° push-up test. Compared to 75% reported by Chen et al. (
Interestingly, Chen et al. (
Test scores were comparable between children with overweight and healthy weight in the current sample and a sample of age-matched Portuguese children (
There were no significant associations between curl-up test scores and the odds of belonging to specific weight categories. FitnessGram® standards require scores between 2–10, 4–14, 6–20, 9–24, 12–24 repetitions for children aged 5–6, 7, 8, 9, and 10–11 years, respectively, in order to achieve HFZ on the curl-up test. It is important to point out that except in third and fifth grades, more than 60% of students who are obese achieved HFZ (Table
There were no significant associations between back saver sit and reach test scores and the odds of belonging to specific weight categories. More children with obesity achieved the requisite score for FitnessGram® HFZ on the back saver sit and reach test in kindergarten through second grade than third through fifth grades (Table
There were several strengths as well as limitations of this study to be noted. The cross-sectional design of the study allowed for inexpensive and very useful analysis of data from a small, but representative sample of the larger population of children in Corpus Christi, Texas. This population of children, 84.3% Hispanic, and 93% economically disadvantaged, well represented the overall high number, 63.5%, of Hispanic people in Corpus Christi, and the median household income of $52,154 (
Limitations of the study findings included the overall small sample size and the high incidence of Hispanic ethnicity and low socioeconomic status in this sample, which decreased generalizability to all populations. This sample, consisting of children from one of the larger elementary schools in the city, was further decreased in size by missing data, consisting primarily of height and weight data, which made it difficult to compare characteristics of the children excluded to those included. Additionally, the rather unexpected finding of a decrease in obesity prevalence from the fourth to the fifth grade cannot be explained by missing data; as stated above, missing data tended to be height and weight measures and there was not a disproportionate number of missing data in the fifth grade that could account for the difference. We theorize that because organized sports often become much more strenuous through elementary and into middle school, increased metabolic demands may have accounted for some of the differences. It is also true that schools in the Corpus Christi area have has been adopting pilot programs focused on district-wide healthy lifestyle initiatives to combat obesity. These initiatives are widely supported by the community and school officials, especially at the elementary school level. Further longitudinal research, including middle and high school data is needed to document the results of these innovative and much needed interventions. Future studies should examine relationships between geographic areas and measures of socioeconomic status, respective park densities and amenities, and average health-related physical fitness measures in schools.
Overweight and obesity remain highly prevalent among elementary school-aged children in Corpus Christi, Texas. Some children with obesity in the current sample achieved isolated HFZ scoring. Children with healthy weight, especially in the lower grades, tended to have similarly low musculoskeletal fitness as peers with overweight and obesity. It is plausible that spikes observed in obesity prevalence in third through fifth grades are at least in part symptomatic of poor musculoskeletal fitness earlier on, especially in kindergarten. Therefore, greater attention should be paid to the scores themselves, especially among children who score adequately but on the lower end of the HFZ standards. The 90° push test was most consistent at showing significant odds of being obese relative to having a healthy weight. Additional research including a larger and more diverse sample size, longitudinal design, and possibly qualitative data may help further explain the interesting and significant findings of this study.
As noted earlier, there is often a lack of opportunities for physical activity, particularly in economically disadvantaged communities. Since children spend upwards of eight daily hours at school in a presumably safe environment, it would seem optimal that they achieve most, if not all, of the recommended 60 daily minutes of physical activity in that setting. Increasing the amount of physical activity encouraged by the school in classes other than physical education and designing interventions that go beyond the school to actively involve families and communities are broad goals for this community and have shown to be most beneficial in improving healthy lifestyles across the country. Given the association between motor skill competence and health-related physical fitness, it is concluded that there is a need for early and focused school-based interventions that leverage both known and novel strategies to effectively improve motor skill competence and neuromuscular fitness in children in Corpus Christi.
Datasets are available on request. The raw data supporting the conclusions of this manuscript will be made available by the authors, without undue reservation, to any qualified researcher.
TA conceived the study, co-designed the study, performed statistical analyses and interpretation, and co-drafted the manuscript. TG co-designed the study, performed statistical analyses, and co-drafted the manuscript. H-CF performed statistical analyses, and co-drafted the manuscript. All authors have read and approved the final version of the manuscript, and agree with the order of presentation of the authors. TA takes responsibility for the integrity of this work as a whole, from inception to finished article.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.