Reliability of the biceps curl test and proposed percentiles in schoolchildren living at moderate altitude in Peru

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A total of 1103 schoolchildren aged 6 to 17 years (500 boys and 603 girls) were evaluated. Weight and height were evaluated and Body Mass Index (BMI) and Tri Ponderal Index (TPI) were calculated. The right and left hand biceps curl was evaluated in 30 seconds. Children aged 6 to 11 years used a 1 kg dumbbell and those aged 12 to 17 years used a 2 kg dumbbell. Percentiles were calculated using the LMS method. The values of the relative Technical Error of Measurement (TEM%) of the biceps curl test of both hands ranged from 0.48 to 2.89%. The intraclass correlation coefficient (ICC) evidenced high values of 0.93 to 0.99. The Bland-Altman plot showed wide limits of agreement (-1.28 to 1.29 rep). It was verified that the biceps curl is a reliable test to evaluate strength endurance in children and adolescents. The values showed stability and wide limits of agreement. In addition, the proposed percentiles are useful to evaluate and monitor the strength endurance performance of both arms. Reliability strength endurance biceps curl children adolescents percentiles Figures Figure 1 Figure 2 Figure 3 Introduction The assessment of overall muscle strength is an important component of the physical examination that can reveal information about neurological deficits, muscle weakness, or lack of muscle endurance 1 , from infancy to senescence 2 . For example, in children and adolescents it is essential to monitor activities of daily living such as self-care, walking, running, jumping among other skills 3 , 4 . These actions not only promote proper social interaction, but also play an essential role in the prevention of diseases in adulthood. It is a multidisciplinary practice that involves several professionals, including nurses, physicians, physical therapists, occupational therapists, chiropractors, and other experts such as physical education and sports teachers 1 . Muscular strength in general is determined by three basic concepts which are maximal strength, muscular power and strength endurance. The first refers to the amount of force exerted by a muscle or muscle group to produce a single maximal effort. While the second, refers to the ability to develop a maximal force in the shortest possible time (e.g., such as accelerating, jumping and throwing) and the third, strength endurance, is the ability of muscles to exert a force against a resistance over a period of time 5 . Indeed, the assessment of strength endurance at the school level is crucial both for activities of daily living, as well as for the sporting arena. This assessment makes it possible to identify the level of muscular endurance of schoolchildren, which is essential to maintain performance and prevent muscle fatigue during sustained efforts. In general, strength endurance measures are evaluated as part of a battery of physical fitness tests in schoolchildren related to health or sports performance 6 . Tests often used are hand grip strength, flexion and extension of arms on the floor (push-ups), suspension on a barbell, abdominal muscular endurance, among others 7 , 8 . To our knowledge, this biceps curl test, has not been applied in schoolchildren, nor included in any battery of physical fitness tests, although it has been widely used in young adult, middle-aged and elderly populations 9 – 12 . Therefore, evidencing the reliability of the biceps curl test in school children and adolescents is a crucial process to ensure that the results obtained are accurate and reproducible. The standard biceps curl test is a commonly used test to measure the strength and function of the biceps brachii and is widely used to control and monitor intervention programs in various populations 9 . This test is characterized by being field-based, rapid and serves to measure the strength endurance of the upper body (arms) and provides essential information about the physical condition and health level of a person 6 , 13 . Indeed, in contexts where convenient instruments for measuring strength endurance are not available, such as in many moderate altitude geographic regions of Peru, this test may be a viable alternative. Therefore, the objective of this study was to verify the reliability of the biceps curl test in children and adolescents from a moderate altitude region of Peru. Additionally, a second objective was to provide reference values of the biceps curl test according to chronological age and sex. Methodology Type of study and sample A descriptive (cross-sectional) study was carried out in schoolchildren living in a city of moderate altitude in Peru. The sample consisted of 1103 schoolchildren aged 6 to 17 years (500 males and 603 females). The sample selection was non-probabilistic (accidental). The schoolchildren participated voluntarily in the study and were recruited from 4 state schools in the urban area of Arequipa (Peru). This city is located 2320 meters above sea level and is situated south of Lima (capital of Peru) 14 . In Peru, the school system is divided into three levels: early education (3 to 5 years), primary education (6 to 11 years) and secondary education (12 to 17 years). The study was approved by the ethics committee of the Universidad Católica Santa María de Arequipa (Peru) (UCSM-096-2022) and was conducted in accordance with the Declaration of Helsinki for Human Subjects. The parents of the children and adolescents authorized the participation of each of their children and the schoolchildren signed the consent form, authorizing the evaluation of weight and height measurements and the muscular endurance strength test (biceps curl). Schoolchildren who attended physical education classes in their schools once a week, those within the established age range (6 to 17 years old) were included. Schoolchildren who practiced any sport outside school hours and those who had some type of physical disability that prevented the evaluation of the anthropometric tests and the biceps curl were excluded. Techniques and instruments The anthropometric data and the muscle strength test were collected at the schools' facilities. The group of evaluators consisted of 02 physical education teachers with extensive experience in physical evaluations. Student data (date of birth, sex and year of study) were collected from the school administration. A group data collection form was constructed, where data such as date of birth, date of evaluation, sex, anthropometric data (weight, height), and the right and left hand biceps curl test were recorded. Anthropometric measurements were evaluated following the recommendations of Ross & Marfell-Jones 15 . Body weight and height were measured with as little clothing as possible (shorts, t-shirt and no shoes). Weight (kg) was assessed with a Seca brand digital scale with an accuracy of (100g) and a scale of (0 to 150kg). The scale is placed on a flat and stable surface. The participant is asked to stand still in the center of the scale until the weight is recorded. Height (m) was assessed using a Seca brand aluminum stadiometer graduated in millimeters with a scale of (0 to 2.50m). The head was positioned according to Frankfort's plane (an imaginary line passing from the lower edge of the eye orbit to the upper edge of the ear canal). Participants stood barefoot, with heels together and back straight against the stadiometer. The Tri-Ponderal Index TPI (kg/m3) was calculated through the formula [TPI = Weight(kg)/Height(m)3]. This indicator is suggested for moderate altitude populations 16 . Body Mass Index (kg/m2) was also calculated with the formula: [BMI = Weight(kg)/Height(m)2]. The biceps curl test (30 seconds) was evaluated sitting on a chair. The participant holds a 1kg dumbbell (children of both sexes from primary level 6 to 11 years old) and a 2kg dumbbell from secondary level adolescents of both sexes from 12 to 17 years old. To evaluate this test, the protocol suggested by Rikli, Jones 17 was followed. The exercise starts with the arm fully extended, flexing the elbow to bend the weight towards the shoulder and then deliberately lowering it. This cycle involves bending the elbows to lift the dumbbell and returning to the starting position as many times as possible for 30 seconds. The test was performed with both the right and left arm. It was performed twice to verify the relative technical measurement error TEM%. It was considered 3 minutes of rest between the first and second measurement as described by Matos et al, 18 . Statistics The normal distribution of the anthropometric data (weight and height) and the biceps curl test were verified by means of the Kolmogorov-Smirnov test. To analyze the data statistically, the sample was divided into two groups: primary level (6 to 11 years) and secondary level (12 to 17 years). Descriptive statistics were calculated: mean, standard deviation, and range. Differences between both sexes and both age groups were determined by t-test for independent samples. The intraclass correlation coefficient (ICC) and Bland-Altman diagrams 19 were also used to evaluate the concordance between test and retest for the biceps curl. The LMS method 20 was used to construct the percentiles. The curves L, M and S represent skewness (lambda), median (mu) and coefficient of variation (sigma). The LMS method uses the Box-Cox transformation to fit the data distribution to a normal distribution by minimizing the effects of skewness. The L, M and S parameters were calculated according to the maximum penalized method 21 . Data processing was performed using LMS Chartmaker Pro software (The Institute of Child Health, London, UK) 22 . For all cases, p < 0.05 was adopted and calculations were performed in Excel spreadsheets, SPSS 18.0 and MedCalc 11.1.0. Results The anthropometric variables characterizing the sample of schoolchildren living at moderate altitude in Peru are shown in Table 1 . Males showed greater weight at 11, 15, 16 and 17 years of age in relation to females (p > 0.5). There were also differences in height and TPI at older ages. Males presented greater height and TPI than females from 13 to 17 years of age (p < 0.05). There were no significant differences at other ages. Table 1 Anthropometric characteristics of the schoolchildren studied. Age (years) Males Females n Weight (kg) Height (cm) BMI (kg/m 2 ) TPI (kg/m 3 ) n Weight (kg) Height (cm) BMI (kg/m 2 ) TPI (kg/m 3 ) x̅ SD x̅ SD x̅ SD x̅ SD x̅ SD x̅ SD x̅ SD x̅ SD Primary education 6 36 24.2 5.0 118.2 6.5 17.2 2 14.6 1.6 35 23.4 3.6 119.5 4.8 16.4 2.1 13.7 1.8 7 37 28.2 6.4 123.2 6.7 18.4 2.8 14.9 2.0 36 26.3 5.4 123.2 6.0 17.2 2.4 14 1.8 8 38 29.6 5.6 128.5 5.2 17.8 2.3 13.9 1.6 39 30.1 7.3 127.5 6.9 18.3 3.0 14.4 2.1 9 52 35.6 8.6 132.6 8.6 20.0 3.3 15.1 2.4 70 33.8 8.6 132.7 7.2 19.0 3.5 14.3 2.4 10 72 39.4 9.0 137.3 7.0 20.8 4.1 15.2 3.2 64 40.9 10.7 140.1 8.6 20.7 4.3 14.8 3.2 11 62 49.0* 12.8 148.6 9.1 21.9 3.8 14.7 2.2 47 43.8 8.1 147.4 6.9 20.1 3.1 13.6 2.2 Secondary education 12 68 47.5 9.9 152.6 7.9 20.3 3.4 13.3 2.2 54 47.5 8.0 151.9 5.5 20.5 3.0 13.5 2.0 13 47 53.3 10.9 160.4* 7.4 20.6 3.5 12.9* 2.1 40 52 8.6 153.1 5.6 22.1 2.8 14.4 1.8 14 50 55.4 8.7 164.1* 6.9 20.5 2.5 12.5* 1.5 38 54.4 6.1 154.8 4.3 22.7 2.1 14.6 1.3 15 47 61.0* 9.7 165.8* 5.1 22.2 3.3 13.4* 2.1 38 55.7 9.0 155.7 5.1 22.9 3.2 14.7 2.1 16 55 59.4* 6.8 167.7* 6.1 21.1 2.1 12.6* 1.4 39 56.1 13.6 155.3 5.0 23.3 5.8 15 3.9 17 30 63.7* 14.8 167.4* 4.6 22.7 5.1 13.6* 3.1 30 55.0 8.1 155.5 3.7 22.7 3.1 14.6 2.0 Legend: X: mean, SD: standard deviation, BMI: body mass index, TPI: triponderal index, *: significant difference in relation to female (p < 0.05). Tables 2 and 3 show the reliability values of the biceps curl of both hands. It is observed that both in the right and left hand the values of the TEM% ranged from 0.48 to 2.89% in all ages and in both sexes. Meanwhile, the CCI (95% CI) showed high values, ranging from 0.93 to 0.99 in all ages and in both sexes. In general, in both test and retest measures there were no significant differences (p > 0.05), being these measures stable. Table 3 . Reliability values (test and retest) of the left arm biceps curl by age and sex. Figures 1 and 2 show the Bland-Altman plot applied for the test and re-tests of the biceps curl test in both sexes. The mean difference in the primary and secondary level boys for both hands were similar (for the right hand it was 1.02 ± 2.39 rep. and for the left hand it was 1.02 ± 2.39 rep). In primary level girls were also similar to boys, for example, for the right hand it was 1.02 ± 2.39 rep. and for the left hand it was 1.02 ± 2.39 rep. In children at the secondary level, the results were also similar in both hands and both sexes. In boys, the mean difference for right hand was 1.02 ± 2.39 rep and for left hand was 1.02 ± 2.39 rep). In girls, the mean differences for the right hand reflected 1.02 ± 2.39 rep and for left hand yielded 1.02 ± 2.39 rep). In general, the limits of agreement for both sexes at the primary level (both hands) ranged from − 1.10 to 1.19rep, and similarly at the secondary level the values ranged from − 1.28 to 1.29 repetitions. In all cases, the values were acceptable. The comparisons of the biceps curl tets between both sexes (primary and secondary) are observed in Fig. 3 . At the primary level, it is observed that the muscular strength endurance of both arms (right and left) are similar from 6 to 10 years of age in both sexes, there were no significant differences (p > 0.05), these values ranged from ∼ -0.2 to 1.2 repetitions. However, at 11 years of age, males presented greater muscular strength endurance than their similar females of the same age (∼ 3 to 3.2repetitions) (p 0.05). From the age of 13 to 17 years, males present higher values in muscular strength endurance of both arms in relation to females (p < 0.05). These values range from ∼4.9 to 14.8 repetitions. Table 4 shows the percentiles developed to evaluate the biceps curl of primary and secondary school children by age and sex (P5, P15, P25, P50, P75, P85 and P95). In both sexes it is observed that the 50th percentile increases as age advances up to 14 years of age, then at 15 to 17 years of age the values stabilize in both sexes. Table 4. Biceps curl values (right and left described in percentiles according to age and sex. Discussion The results of the study have evidenced that the strength endurance test (biceps curl) of both hands is reliable to be applied to primary and secondary school children living in a moderate altitude region of Peru. These findings are consistent with other studies that have sought similar reliability objectives using the biceps curl test in adolescents 23 , young adults 24 and adults with some diseases 25 and without diseases 26 . The weights used in the dumbbells in these studies were 2.27 to 3.63 kg as opposed to those used in the present study, which were 1kg for children at the primary level (6 to 11 years) and 2 kg for adolescents at the secondary level (12 to 17 years). In general, children of both sexes during the growth stage rapidly increase muscle strength, with boys having advantages over girls during adolescence 27 . Therefore, the weights of the dumbbells at the primary level of 1kg were increased to 2kg for the secondary level. For muscle strength is proportional to the cross-sectional area of skeletal muscle, meaning that the growth curves of strength parallel the growth curves of body weight and skeletal muscle mass 28 . In fact, when comparing muscle strength (biceps curl) during childhood (primary education), there were no significant differences between both sexes. However, during adolescence (secondary education), adolescents of both sexes continued to increase strength endurance linearly until around 14 years of age, and then reached relative stability at older ages. These findings are in agreement with the literature, where they indicate that optimal development of muscle mass and muscle strength are reached during adolescence 29 , 30 and peak in early adulthood, then decline with age from approximately the fifth decade onwards 31 , 32 . Therefore, assessing muscular endurance during school age is relevant, as it can help prevent several common disorders, such as osteoporosis and sarcopenia, later in life 30 , 33 , 34 . The reliability demonstrated in some studies described above, reinforces the usefulness of the biceps curl test as an effective tool for muscle strength assessment in pediatric populations, which may be beneficial for measuring lower body musculoskeletal strength and power in school children 35 . In addition, it can be included in physical education, training and rehabilitation programs in various populations 23 , 36 . The strength endurance test (biceps curl) is reliable for assessing primary and secondary school children in a moderate altitude region of Peru. This suggests that the test can be used effectively in these contexts and can be included in a battery of physical tests in growing and developing populations. The percentiles developed in this study show reference values to evaluate muscular endurance by means of the biceps curl test for children and adolescents in a region of moderate altitude in Peru. These results suggest the use of percentiles as a fundamental tool to assess muscular endurance in children and adolescents by age and sex. This proposal will allow accurate and reliable assessments to monitor muscular development, adapt to physical education programs, youth sports training programs and to monitor physical health from infancy to adolescence. Several studies have prioritized the assessment of muscular endurance through push-up, barbell suspension, isometric strength tests 37 – 39 . The results obtained through these tests show that they are important for determining physical fitness and muscle development in children and adolescents. Muscular endurance, regardless of the type of test to be evaluated, reflects the capacity of a muscle group to exert submaximal force for prolonged periods and can be evaluated with standardized tests and can even serve to relate to other indicators 5 . In essence, the assessment of general fitness requires sex- and age-specific reference values against which individual and population fitness status can be compared 38 . This tool allows for meaningful interpretation of development in children and adolescents and provides comprehensive feedback to teachers, adolescents and children, parents, and public policy makers 40 . Some recent studies consider that the assessment of physical fitness and especially muscular strength endurance should be considered as a marker of health 4143 . This requires a distribution of percentiles, which are often typically classified into five categories: ≤p10 as very poor, p10 to ≤ p25 poor, p25 to ≤ p75 medium, p75 to ≤ p90 good and ≥ p90 very good 41 , 44 . Other studies indicate categorizing fitness into three categories: ≤p15 can be interpreted as a low level or a warning sign, between p15 to p85 as adequate and ≥ p85 as a high level of fitness 45 , 46 . This study provides useful tools, by describing percentiles and three categories (≤ p15 poor, between p15 to (≤ p85 as adequate and ≥ p85 high muscular endurance), to assess strength endurance in children and adolescents. These cut-off points allow accurate interpretation of test results and help identify those who might benefit from specific interventions to improve their muscular endurance. The study has some limitations that should be acknowledged. For example, the sample selection was non-probabilistic, so the results obtained in this study cannot be generalized to other populations. Also, it was not possible to evaluate an upper limb muscle strength test as a criterion method. In addition, future studies should use other field tests to achieve concurrent validity in pediatric populations. It is also necessary to highlight the strengths of this study. First, it is one of the first studies to use the biceps curl to assess strength endurance in children and adolescents living in a moderate altitude region of Peru. Secondly, the test proved to be reliable and the test-retest values evidenced stability and wide limits of agreement. Third, the percentiles developed provide useful tools to evaluate and monitor strength endurance performance of both arms according to age and sex, thus contributing to a better understanding and follow-up of muscle development in primary and secondary school children. This tool can also be used to design specific training programs to improve physical performance, prevent muscle fatigue and reduce the risk of injury, thus contributing to their comprehensive development and long-term well-being. Conclusion In conclusion, this study verified that the biceps curl test is reliable for children and adolescents living in a moderate altitude region of Peru. The retest values evidenced stability and wide limits of agreement. In addition, the proposed percentiles serve to evaluate and monitor the performance of strength endurance of both arms according to age and sex. The results suggest their use and application as an effective tool for the evaluation and monitoring of muscular endurance in these populations. Declarations Author Contribution Authors’ contributions M.C.B., R.G.C., and R.V.E. contributed to the design of the research study. M.C.B, R.G.C., J.S.T., and L.T.P. collected data. M.C.B., R.G.C., L.C.C., M.A., and P.O., contributed to the discussion, wrote the manuscript and reviewed/edited the manuscript. M.C.B. and R.G.C edited and reviewed the manuscript. All authors revised and agreed on the views expressed in the manuscript. Data availability Te dataset used and analyzed during the current study are available from the corresponding author on reasonable request. References Naqvi ,U., & Sherman, AL. Muscle Strength Grading. 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Vaishya, et al. Hand grip strength as a proposed new vital sign of health: a narrative review of evidences. J Health Popul Nutr, 43 , 7. https://doi.org/10.1186/s41043-024-00500-y (2024). Jurak, G., Kovač, M., Sember, V., & Starc G. 30 years of SLOfit: Its legacy and perspective. Spor Hekimliği Dergisi, Turkish J Sports Med, 54 , 23–27. (2019). De Miguel-Etayo, P., et al. Physical fitness reference standards in European children: the IDEFICS study. Int J Obes (Lond), 38, Suppl 2,S57-66. https: doi.org/10.1038/ijo.2014.136 (2014). Smith, JJ., et al . Behavioral Correlates of Muscular Fitness in Children and Adolescents: A Systematic Review. Sports Med , 49 (6), 887-904. https://doi.org/10.1007/s40279-019-01089-7. (2019). Emeljanovas, A., Physical Fitness and Anthropometric Values Among Lithuanian Primary School Children: Population-Based Cross-Sectional Study. J Strength Cond Res, 34 (2):414-421. https://doi.org/10.1519/JSC.0000000000003387 (2020). Ortega, F.B., et al . Improvements in fitness reduce the risk of becoming overweight across puberty. Med Sci Sports Exerc , 43(10),1891-7. https://doi.org/10.1249/MSS.0b013e3182190d71 (2011). Hobold, E., et al . Reference standards to assess physical fitness of children and adolescents of Brazil: an approach to the students of the Lake Itaipú region-Brazil. PeerJ , 30,5,e4032. https://doi.org/10.7717/peerj.4032 (2017). Gómez-Campos, R., et al . Normative data for handgrip strength in children and adolescents in the Maule Region, Chile: Evaluation based on chronological and biological age. PLoS One , 9 ;13(8):e0201033. doi: 10.1371/journal.pone.0201033 (2018). Additional Declarations No competing interests reported. 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Olivares","email":"","orcid":"","institution":"University of Huelva","correspondingAuthor":false,"prefix":"","firstName":"Pedro","middleName":"R.","lastName":"Olivares","suffix":""},{"id":325971122,"identity":"65c9c469-a767-4035-81ad-c950ecc9868f","order_by":6,"name":"Rossana Gomez-Campos","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5klEQVRIiWNgGAWjYBADHjD5AYjZ2EnRwjgDpIWZFKuYwRoJaTFvb3/84WfbHRn+9tNpj21+bZPnY2Zg/PAxB7cWmTNnzCR7257xSJzJ3W6c23fbsI2ZgVly5jbcWiQkctgYeNsO8xgw5G6Tzu25zQjUwsbMi1dL+uOPf0Fa+N9uk7bsuW1PhJYEA2mwLRJAWxh+3E4krIXnjJm0zLnDPBI33m437G24ndzGzNiM3y/s7Y8/vik7bM/fn7vtwY8/t23ntzcf/PARjxZkwMbA2AaiGRuIUw/WwvCHaMWjYBSMglEwggAALN1MnPd3xoYAAAAASUVORK5CYII=","orcid":"","institution":"University of Huelva","correspondingAuthor":true,"prefix":"","firstName":"Rossana","middleName":"","lastName":"Gomez-Campos","suffix":""},{"id":325971123,"identity":"1964856a-e90b-4c72-8fe4-65efee99e579","order_by":7,"name":"Luis Edwin Torres-Paz","email":"","orcid":"","institution":"Universidad César Vallejo","correspondingAuthor":false,"prefix":"","firstName":"Luis","middleName":"Edwin","lastName":"Torres-Paz","suffix":""}],"badges":[],"createdAt":"2024-06-17 16:21:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4595333/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4595333/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-89656-z","type":"published","date":"2025-03-24T15:57:53+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60621890,"identity":"01c65bff-adb9-4638-a48f-897b5d76bfeb","added_by":"auto","created_at":"2024-07-18 21:07:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":436790,"visible":true,"origin":"","legend":"\u003cp\u003eBland-Altman graph evaluating concordance between the test and retest of the biceps curl test of primary and secondary school children.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4595333/v1/3ea4f8578b681e40bb9b48af.png"},{"id":60621169,"identity":"7859e373-005b-4414-b857-e85ebb6ec14f","added_by":"auto","created_at":"2024-07-18 20:59:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":411781,"visible":true,"origin":"","legend":"\u003cp\u003eBland-Altman plot evaluating concordance between the test and retest of the biceps curl test of primary and secondary school girls.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4595333/v1/0896863c736f6fffd73b3e6a.png"},{"id":60621170,"identity":"594ad737-9002-4e51-b7a5-3c542ca818c6","added_by":"auto","created_at":"2024-07-18 20:59:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":336370,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of mean biceps curl values between both sexes by age and level of school education (primary and secondary).\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4595333/v1/636879a08bddbaeb801c50f2.png"},{"id":79605080,"identity":"c560e752-5199-41ff-b150-b25a3c352de3","added_by":"auto","created_at":"2025-03-31 16:10:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2011861,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4595333/v1/68df10bf-8f4e-4499-b90f-db6e84d53fc8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reliability of the biceps curl test and proposed percentiles in schoolchildren living at moderate altitude in Peru","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe assessment of overall muscle strength is an important component of the physical examination that can reveal information about neurological deficits, muscle weakness, or lack of muscle endurance\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e, from infancy to senescence\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. For example, in children and adolescents it is essential to monitor activities of daily living such as self-care, walking, running, jumping among other skills\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. These actions not only promote proper social interaction, but also play an essential role in the prevention of diseases in adulthood.\u003c/p\u003e \u003cp\u003eIt is a multidisciplinary practice that involves several professionals, including nurses, physicians, physical therapists, occupational therapists, chiropractors, and other experts such as physical education and sports teachers\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMuscular strength in general is determined by three basic concepts which are maximal strength, muscular power and strength endurance. The first refers to the amount of force exerted by a muscle or muscle group to produce a single maximal effort. While the second, refers to the ability to develop a maximal force in the shortest possible time (e.g., such as accelerating, jumping and throwing) and the third, strength endurance, is the ability of muscles to exert a force against a resistance over a period of time\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIndeed, the assessment of strength endurance at the school level is crucial both for activities of daily living, as well as for the sporting arena. This assessment makes it possible to identify the level of muscular endurance of schoolchildren, which is essential to maintain performance and prevent muscle fatigue during sustained efforts.\u003c/p\u003e \u003cp\u003eIn general, strength endurance measures are evaluated as part of a battery of physical fitness tests in schoolchildren related to health or sports performance\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Tests often used are hand grip strength, flexion and extension of arms on the floor (push-ups), suspension on a barbell, abdominal muscular endurance, among others\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTo our knowledge, this biceps curl test, has not been applied in schoolchildren, nor included in any battery of physical fitness tests, although it has been widely used in young adult, middle-aged and elderly populations\u003csup\u003e\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. Therefore, evidencing the reliability of the biceps curl test in school children and adolescents is a crucial process to ensure that the results obtained are accurate and reproducible.\u003c/p\u003e \u003cp\u003eThe standard biceps curl test is a commonly used test to measure the strength and function of the biceps brachii and is widely used to control and monitor intervention programs in various populations\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. This test is characterized by being field-based, rapid and serves to measure the strength endurance of the upper body (arms) and provides essential information about the physical condition and health level of a person\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIndeed, in contexts where convenient instruments for measuring strength endurance are not available, such as in many moderate altitude geographic regions of Peru, this test may be a viable alternative. Therefore, the objective of this study was to verify the reliability of the biceps curl test in children and adolescents from a moderate altitude region of Peru. Additionally, a second objective was to provide reference values of the biceps curl test according to chronological age and sex.\u003c/p\u003e"},{"header":"Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eType of study and sample\u003c/h2\u003e \u003cp\u003eA descriptive (cross-sectional) study was carried out in schoolchildren living in a city of moderate altitude in Peru. The sample consisted of 1103 schoolchildren aged 6 to 17 years (500 males and 603 females). The sample selection was non-probabilistic (accidental).\u003c/p\u003e \u003cp\u003eThe schoolchildren participated voluntarily in the study and were recruited from 4 state schools in the urban area of Arequipa (Peru). This city is located 2320 meters above sea level and is situated south of Lima (capital of Peru)\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. In Peru, the school system is divided into three levels: early education (3 to 5 years), primary education (6 to 11 years) and secondary education (12 to 17 years).\u003c/p\u003e \u003cp\u003e The study was approved by the ethics committee of the Universidad Cat\u0026oacute;lica Santa Mar\u0026iacute;a de Arequipa (Peru) (UCSM-096-2022) and was conducted in accordance with the Declaration of Helsinki for Human Subjects.\u003c/p\u003e \u003cp\u003e The parents of the children and adolescents authorized the participation of each of their children and the schoolchildren signed the consent form, authorizing the evaluation of weight and height measurements and the muscular endurance strength test (biceps curl).\u003c/p\u003e \u003cp\u003eSchoolchildren who attended physical education classes in their schools once a week, those within the established age range (6 to 17 years old) were included. Schoolchildren who practiced any sport outside school hours and those who had some type of physical disability that prevented the evaluation of the anthropometric tests and the biceps curl were excluded.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eTechniques and instruments\u003c/h2\u003e \u003cp\u003eThe anthropometric data and the muscle strength test were collected at the schools' facilities. The group of evaluators consisted of 02 physical education teachers with extensive experience in physical evaluations. Student data (date of birth, sex and year of study) were collected from the school administration.\u003c/p\u003e \u003cp\u003eA group data collection form was constructed, where data such as date of birth, date of evaluation, sex, anthropometric data (weight, height), and the right and left hand biceps curl test were recorded.\u003c/p\u003e \u003cp\u003eAnthropometric measurements were evaluated following the recommendations of Ross \u0026amp; Marfell-Jones\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Body weight and height were measured with as little clothing as possible (shorts, t-shirt and no shoes). Weight (kg) was assessed with a Seca brand digital scale with an accuracy of (100g) and a scale of (0 to 150kg). The scale is placed on a flat and stable surface. The participant is asked to stand still in the center of the scale until the weight is recorded.\u003c/p\u003e \u003cp\u003eHeight (m) was assessed using a Seca brand aluminum stadiometer graduated in millimeters with a scale of (0 to 2.50m). The head was positioned according to Frankfort's plane (an imaginary line passing from the lower edge of the eye orbit to the upper edge of the ear canal). Participants stood barefoot, with heels together and back straight against the stadiometer. The Tri-Ponderal Index TPI (kg/m3) was calculated through the formula [TPI\u0026thinsp;=\u0026thinsp;Weight(kg)/Height(m)3]. This indicator is suggested for moderate altitude populations\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Body Mass Index (kg/m2) was also calculated with the formula: [BMI\u0026thinsp;=\u0026thinsp;Weight(kg)/Height(m)2].\u003c/p\u003e \u003cp\u003eThe biceps curl test (30 seconds) was evaluated sitting on a chair. The participant holds a 1kg dumbbell (children of both sexes from primary level 6 to 11 years old) and a 2kg dumbbell from secondary level adolescents of both sexes from 12 to 17 years old. To evaluate this test, the protocol suggested by Rikli, Jones\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e was followed. The exercise starts with the arm fully extended, flexing the elbow to bend the weight towards the shoulder and then deliberately lowering it. This cycle involves bending the elbows to lift the dumbbell and returning to the starting position as many times as possible for 30 seconds. The test was performed with both the right and left arm. It was performed twice to verify the relative technical measurement error TEM%. It was considered 3 minutes of rest between the first and second measurement as described by Matos et al, \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistics\u003c/h2\u003e \u003cp\u003eThe normal distribution of the anthropometric data (weight and height) and the biceps curl test were verified by means of the Kolmogorov-Smirnov test. To analyze the data statistically, the sample was divided into two groups: primary level (6 to 11 years) and secondary level (12 to 17 years). Descriptive statistics were calculated: mean, standard deviation, and range. Differences between both sexes and both age groups were determined by t-test for independent samples. The intraclass correlation coefficient (ICC) and Bland-Altman diagrams\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e were also used to evaluate the concordance between test and retest for the biceps curl. The LMS method\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e was used to construct the percentiles. The curves L, M and S represent skewness (lambda), median (mu) and coefficient of variation (sigma). The LMS method uses the Box-Cox transformation to fit the data distribution to a normal distribution by minimizing the effects of skewness. The L, M and S parameters were calculated according to the maximum penalized method\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. Data processing was performed using LMS Chartmaker Pro software (The Institute of Child Health, London, UK)\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. For all cases, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was adopted and calculations were performed in Excel spreadsheets, SPSS 18.0 and MedCalc 11.1.0.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe anthropometric variables characterizing the sample of schoolchildren living at moderate altitude in Peru are shown in Table\u0026nbsp;\u003cspan\u003e1\u003c/span\u003e. Males showed greater weight at 11, 15, 16 and 17 years of age in relation to females (p\u0026thinsp;\u0026gt;\u0026thinsp;0.5). There were also differences in height and TPI at older ages. Males presented greater height and TPI than females from 13 to 17 years of age (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). There were no significant differences at other ages.\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eAnthropometric characteristics of the schoolchildren studied.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"9\"\u003e\n \u003cp\u003eMales\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"9\"\u003e\n \u003cp\u003eFemales\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eWeight (kg)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eHeight (cm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eTPI (kg/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003en\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eWeight (kg)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eHeight (cm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eTPI (kg/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex̅\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"19\"\u003e\n \u003cp\u003e\u003cstrong\u003ePrimary education\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e118.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e119.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e123.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e123.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e128.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e127.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e132.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e132.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e137.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e140.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e49.0*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e148.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e43.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e147.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"19\"\u003e\n \u003cp\u003e\u003cstrong\u003eSecondary education\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e152.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e151.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e53.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e160.4*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.9*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e153.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e164.1*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.5*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e54.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e154.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61.0*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e165.8*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.4*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e155.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e59.4*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e167.7*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.6*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e56.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e155.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e63.7*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e167.4*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.6*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e155.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eLegend: X: mean, SD: standard deviation, BMI: body mass index, TPI: triponderal index, *: significant difference in relation to female (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\n\u003cp\u003eTables\u0026nbsp;\u003cspan\u003e2\u003c/span\u003e and \u003cspan\u003e3\u003c/span\u003e show the reliability values of the biceps curl of both hands. It is observed that both in the right and left hand the values of the TEM% ranged from 0.48 to 2.89% in all ages and in both sexes. Meanwhile, the CCI (95% CI) showed high values, ranging from 0.93 to 0.99 in all ages and in both sexes. In general, in both test and retest measures there were no significant differences (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), being these measures stable.\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1721140608.png\"\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv\u003e\n \u003cdiv align=\"left\"\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e. Reliability values (test and retest) of the left arm biceps curl by age and sex.\u003c/div\u003e\n \u003cdiv align=\"left\"\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1721140607.png\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\n\u003cp\u003eFigures \u003cspan\u003e1\u003c/span\u003e and \u003cspan\u003e2\u003c/span\u003e show the Bland-Altman plot applied for the test and re-tests of the biceps curl test in both sexes. The mean difference in the primary and secondary level boys for both hands were similar (for the right hand it was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep. and for the left hand it was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep). In primary level girls were also similar to boys, for example, for the right hand it was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep. and for the left hand it was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep.\u003c/p\u003e\n\u003cp\u003eIn children at the secondary level, the results were also similar in both hands and both sexes. In boys, the mean difference for right hand was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep and for left hand was 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep). In girls, the mean differences for the right hand reflected 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep and for left hand yielded 1.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39 rep).\u003c/p\u003e\n\u003cp\u003eIn general, the limits of agreement for both sexes at the primary level (both hands) ranged from \u0026minus;\u0026thinsp;1.10 to 1.19rep, and similarly at the secondary level the values ranged from \u0026minus;\u0026thinsp;1.28 to 1.29 repetitions. In all cases, the values were acceptable.\u003c/p\u003e\n\u003cp\u003eThe comparisons of the biceps curl tets between both sexes (primary and secondary) are observed in Fig.\u0026nbsp;\u003cspan\u003e3\u003c/span\u003e. At the primary level, it is observed that the muscular strength endurance of both arms (right and left) are similar from 6 to 10 years of age in both sexes, there were no significant differences (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), these values ranged from \u0026sim; -0.2 to 1.2 repetitions. However, at 11 years of age, males presented greater muscular strength endurance than their similar females of the same age (\u0026sim; 3 to 3.2repetitions) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\n\u003cp\u003eIn secondary school children, there were no differences at 12 years of age in both hands (right and left) (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). From the age of 13 to 17 years, males present higher values in muscular strength endurance of both arms in relation to females (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). These values range from \u0026sim;4.9 to 14.8 repetitions.\u003c/p\u003e\n\u003cp\u003eTable \u003cspan\u003e4\u003c/span\u003e shows the percentiles developed to evaluate the biceps curl of primary and secondary school children by age and sex (P5, P15, P25, P50, P75, P85 and P95). In both sexes it is observed that the 50th percentile increases as age advances up to 14 years of age, then at 15 to 17 years of age the values stabilize in both sexes.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u003c/strong\u003e Biceps curl values (right and left described in percentiles according to age and sex.\u003c/p\u003e\n\u003cdiv\u003e\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1721140795.png\"\u003e\u003cbr\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe results of the study have evidenced that the strength endurance test (biceps curl) of both hands is reliable to be applied to primary and secondary school children living in a moderate altitude region of Peru.\u003c/p\u003e \u003cp\u003eThese findings are consistent with other studies that have sought similar reliability objectives using the biceps curl test in adolescents\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, young adults\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e and adults with some diseases\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e and without diseases\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe weights used in the dumbbells in these studies were 2.27 to 3.63 kg as opposed to those used in the present study, which were 1kg for children at the primary level (6 to 11 years) and 2 kg for adolescents at the secondary level (12 to 17 years).\u003c/p\u003e \u003cp\u003eIn general, children of both sexes during the growth stage rapidly increase muscle strength, with boys having advantages over girls during adolescence\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. Therefore, the weights of the dumbbells at the primary level of 1kg were increased to 2kg for the secondary level. For muscle strength is proportional to the cross-sectional area of skeletal muscle, meaning that the growth curves of strength parallel the growth curves of body weight and skeletal muscle mass\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn fact, when comparing muscle strength (biceps curl) during childhood (primary education), there were no significant differences between both sexes. However, during adolescence (secondary education), adolescents of both sexes continued to increase strength endurance linearly until around 14 years of age, and then reached relative stability at older ages.\u003c/p\u003e \u003cp\u003eThese findings are in agreement with the literature, where they indicate that optimal development of muscle mass and muscle strength are reached during adolescence\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e and peak in early adulthood, then decline with age from approximately the fifth decade onwards\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. Therefore, assessing muscular endurance during school age is relevant, as it can help prevent several common disorders, such as osteoporosis and sarcopenia, later in life\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe reliability demonstrated in some studies described above, reinforces the usefulness of the biceps curl test as an effective tool for muscle strength assessment in pediatric populations, which may be beneficial for measuring lower body musculoskeletal strength and power in school children\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. In addition, it can be included in physical education, training and rehabilitation programs in various populations\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe strength endurance test (biceps curl) is reliable for assessing primary and secondary school children in a moderate altitude region of Peru. This suggests that the test can be used effectively in these contexts and can be included in a battery of physical tests in growing and developing populations.\u003c/p\u003e \u003cp\u003eThe percentiles developed in this study show reference values to evaluate muscular endurance by means of the biceps curl test for children and adolescents in a region of moderate altitude in Peru.\u003c/p\u003e \u003cp\u003eThese results suggest the use of percentiles as a fundamental tool to assess muscular endurance in children and adolescents by age and sex. This proposal will allow accurate and reliable assessments to monitor muscular development, adapt to physical education programs, youth sports training programs and to monitor physical health from infancy to adolescence.\u003c/p\u003e \u003cp\u003eSeveral studies have prioritized the assessment of muscular endurance through push-up, barbell suspension, isometric strength tests\u003csup\u003e\u003cspan additionalcitationids=\"CR38\" citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. The results obtained through these tests show that they are important for determining physical fitness and muscle development in children and adolescents.\u003c/p\u003e \u003cp\u003eMuscular endurance, regardless of the type of test to be evaluated, reflects the capacity of a muscle group to exert submaximal force for prolonged periods and can be evaluated with standardized tests and can even serve to relate to other indicators\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn essence, the assessment of general fitness requires sex- and age-specific reference values against which individual and population fitness status can be compared\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. This tool allows for meaningful interpretation of development in children and adolescents and provides comprehensive feedback to teachers, adolescents and children, parents, and public policy makers\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSome recent studies consider that the assessment of physical fitness and especially muscular strength endurance should be considered as a marker of health\u003csup\u003e4143\u003c/sup\u003e. This requires a distribution of percentiles, which are often typically classified into five categories: \u0026le;p10 as very poor, p10 to \u0026le;\u0026thinsp;p25 poor, p25 to \u0026le;\u0026thinsp;p75 medium, p75 to \u0026le;\u0026thinsp;p90 good and \u0026ge;\u0026thinsp;p90 very good \u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. Other studies indicate categorizing fitness into three categories: \u0026le;p15 can be interpreted as a low level or a warning sign, between p15 to p85 as adequate and \u0026ge;\u0026thinsp;p85 as a high level of fitness\u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e,\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study provides useful tools, by describing percentiles and three categories (\u0026le;\u0026thinsp;p15 poor, between p15 to (\u0026le;\u0026thinsp;p85 as adequate and \u0026ge;\u0026thinsp;p85 high muscular endurance), to assess strength endurance in children and adolescents. These cut-off points allow accurate interpretation of test results and help identify those who might benefit from specific interventions to improve their muscular endurance.\u003c/p\u003e \u003cp\u003eThe study has some limitations that should be acknowledged. For example, the sample selection was non-probabilistic, so the results obtained in this study cannot be generalized to other populations. Also, it was not possible to evaluate an upper limb muscle strength test as a criterion method. In addition, future studies should use other field tests to achieve concurrent validity in pediatric populations.\u003c/p\u003e \u003cp\u003eIt is also necessary to highlight the strengths of this study. First, it is one of the first studies to use the biceps curl to assess strength endurance in children and adolescents living in a moderate altitude region of Peru. Secondly, the test proved to be reliable and the test-retest values evidenced stability and wide limits of agreement. Third, the percentiles developed provide useful tools to evaluate and monitor strength endurance performance of both arms according to age and sex, thus contributing to a better understanding and follow-up of muscle development in primary and secondary school children. This tool can also be used to design specific training programs to improve physical performance, prevent muscle fatigue and reduce the risk of injury, thus contributing to their comprehensive development and long-term well-being.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, this study verified that the biceps curl test is reliable for children and adolescents living in a moderate altitude region of Peru. The retest values evidenced stability and wide limits of agreement. In addition, the proposed percentiles serve to evaluate and monitor the performance of strength endurance of both arms according to age and sex. The results suggest their use and application as an effective tool for the evaluation and monitoring of muscular endurance in these populations.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthors\u0026rsquo; contributions M.C.B., R.G.C., and R.V.E. contributed to the design of the research study. M.C.B, R.G.C., J.S.T., and L.T.P. collected data. M.C.B., R.G.C., L.C.C., M.A., and P.O., contributed to the discussion, wrote the manuscript and reviewed/edited the manuscript. M.C.B. and R.G.C edited and reviewed the manuscript. All authors revised and agreed on the views expressed in the manuscript.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTe dataset used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eNaqvi ,U., \u0026amp; Sherman, AL. Muscle Strength Grading. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK436008/. (2024).\u003c/li\u003e\n\u003cli\u003eG\u0026oacute;mez-Campos, R. \u003cem\u003eet al\u003c/em\u003e. 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Normative data for handgrip strength in children and adolescents in the Maule Region, Chile: Evaluation based on chronological and biological age. \u003cem\u003ePLoS One\u003c/em\u003e, \u003cstrong\u003e9\u003c/strong\u003e;13(8):e0201033. doi: 10.1371/journal.pone.0201033 (2018).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Reliability, strength endurance, biceps curl, children, adolescents, percentiles","lastPublishedDoi":"10.21203/rs.3.rs-4595333/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4595333/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo verify the reliability of the biceps curl test in children and adolescents and to provide reference values according to chronological age and sex. A total of 1103 schoolchildren aged 6 to 17 years (500 boys and 603 girls) were evaluated. Weight and height were evaluated and Body Mass Index (BMI) and Tri Ponderal Index (TPI) were calculated. The right and left hand biceps curl was evaluated in 30 seconds. Children aged 6 to 11 years used a 1 kg dumbbell and those aged 12 to 17 years used a 2 kg dumbbell. Percentiles were calculated using the LMS method. The values of the relative Technical Error of Measurement (TEM%) of the biceps curl test of both hands ranged from 0.48 to 2.89%. The intraclass correlation coefficient (ICC) evidenced high values of 0.93 to 0.99. The Bland-Altman plot showed wide limits of agreement (-1.28 to 1.29 rep). It was verified that the biceps curl is a reliable test to evaluate strength endurance in children and adolescents. The values showed stability and wide limits of agreement. In addition, the proposed percentiles are useful to evaluate and monitor the strength endurance performance of both arms.\u003c/p\u003e","manuscriptTitle":"Reliability of the biceps curl test and proposed percentiles in schoolchildren living at moderate altitude in Peru","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-18 20:59:27","doi":"10.21203/rs.3.rs-4595333/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-12-11T11:35:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-12-09T10:44:08+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-12-07T08:50:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-25T13:49:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250861576758926056848083589240456660980","date":"2024-11-24T09:56:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"39235507153023245192118207948348284197","date":"2024-11-23T22:10:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"104132134783188926222819117713270262902","date":"2024-11-22T19:34:34+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-22T18:54:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-09-19T14:45:36+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-06-26T04:51:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-06-24T13:02:19+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2024-06-17T16:17:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2c9b4556-fbf9-4019-b872-66d63b73cd97","owner":[],"postedDate":"July 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-31T16:06:27+00:00","versionOfRecord":{"articleIdentity":"rs-4595333","link":"https://doi.org/10.1038/s41598-025-89656-z","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-03-24 15:57:53","publishedOnDateReadable":"March 24th, 2025"},"versionCreatedAt":"2024-07-18 20:59:27","video":"","vorDoi":"10.1038/s41598-025-89656-z","vorDoiUrl":"https://doi.org/10.1038/s41598-025-89656-z","workflowStages":[]},"version":"v1","identity":"rs-4595333","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4595333","identity":"rs-4595333","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}