C L I N I C A L F E AT U R E S
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Test-Retest Reliability of the Star Excursion Balance Test in Primary School Children
DOI: 10.3810/psm.2014.11.2098
Joaquin Calatayud, MSc 1 Sebastien Borreani, PhD 1 Juan Carlos Colado, PhD 1 Fernando Martin, PhD 1 Jorge Flandez, PhD 2 1 Research Group in Sport and Health, Laboratory of Physical Activity and Health, Department of Physical Education and Sports, University of Valencia, Valencia, Spain; 2 Austral University of Chile, Faculty of Pedagogy in Physical Education, Sports, and Recreation, Valdivia, Chile
Abstract
Background: Dynamic balance has been considered a fundamental skill at all ages and is required for normal daily tasks, such as walking, running, or other sports activities. The Star Excursion Balance Test (SEBT) has been widely used in recent years to identify dynamic balance deficits and improvements and to predict the risk of lower extremity injury. However, no study has demonstrated the reliability of the SEBT in children while they are performing the test in a physical education session. Reliability is needed in all measurement tools in order to provide repeatable and consistent data. Objective: To evaluate the reliability of the SEBT in primary school students in the school setting. Methods: Twenty-four healthy children with typical development were tested twice, 2 weeks apart. The tests were conducted by the same single rater and were performed during the physical education class. The test was performed under standardized conditions during the 2 testing sessions and was performed by each subject with both limbs in the 3 directions (anterior, posteromedial, and posterolateral). Four practice trials were performed in each direction before selecting 3 additional distances reached. The best value of these 3 additional measured trials was selected. The paired t test was used to ensure the absence of any systematic bias. Intraclass correlation coefficient, standard error of measurement, 95% confidence intervals (CIs), and minimal change values were calculated to assess reliability and measurement error. Results: The paired t tests revealed no significant differences between test–rest scores. Test–retest reliability for all distances reached was moderate to good. Conclusions: Reliability values suggest that the SEBT is suitable for primary school students. However, it may be more practical and feasible during extracurricular sports participation due to the time constraints and difficulties in using the test in the school setting. Keywords: injury risk; school setting; reliability; dynamic balance
Introduction
Correspondence: Juan Carlos Colado, PhD, Universidad de Valencia (FCAFE), Aulario Multiusos, C/ Gasco Oliag, 3, 46010 Valencia, Spain. Tel: 00-34-963-983-470 Fax: 00-34-963-864-353 E-mail: [email protected]
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Dynamic balance has been considered a fundamental skill at all ages1 and is required for normal daily tasks, such as walking, running, or other sports activities,1,2 especially those activities that require dynamic movements while maintaining control.3 Since sports participation is one of the most frequent causes of injuries,4 and because balance is a predictor of an increased risk to sustain a lower extremity injury such as ankle sprains,5 a test that provides dynamic conditions is required in order to identify balance deficits and to assess fall risk and sports-related injury risk.6 The physical education classes may play an important role in identifying children with poor fitness7 and those at high risk of injuries. Because of their undeveloped neuromuscular system,8 children’s injury rates related to falls and sports participation are elevated.9
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SEBT Reliability in Primary School Children
The Star Excursion Balance Test (SEBT) has been widely used in recent years in both healthy and injured populations to identify dynamic balance deficits and improvements and to predict the risk of lower extremity injury.10 Performing the test requires strength, flexibility, and coordination11 to maintain a single leg stance on one leg while reaching as far as possible with the contralateral leg.2 Reliability is needed in all measurement tools12 to provide repeatable13,14 and consistent15,16 data. Therefore, a reliable test is a precise measure14 that ensures similar results under the same test conditions.15 Despite the fact that the intraclass correlation coefficient (ICC) and standard error of measurement (SEM) values have shown moderate2 to high16–18 reliability for the SEBT in young adults and middle-aged adults, no study has demonstrated the between-session reliability of the SEBT in children who are performing the test in a physical education class. To our knowledge, only 2 recent investigations19,20 have tested the SEBT in schoolchildren, although these were not conducted in order to evaluate the reliability of the test. Furthermore, the use of dynamic balance tests in children is limited to costly systems such as balance platforms6 or the Biodex Balance System.21 Hence, a reliable cost-effective test that could be performed anywhere is needed to obtain dynamic balance measures and to provide useful information to identify those with greater injury risk. Moreover, it has been established that motor fitness, which includes balance and coordination, is a physical health-related component in childhood and adolescence.22 Thus, this study evaluated the relative and absolute test–retest reliability of the SEBT in primary school students in the school setting. We hypothesized that the SEBT would be a reliable measure to assess dynamic balance in this population.
Materials and Methods Participants
Twenty-four children (12 girls and 12 boys; age 11.0 ± 0.8 years, height 152.4 ± 8.7 cm, weight 45.4 ± 8.1 kg, body mass index 19.46 ± 2.63) volunteered to take part in this study. They were required to be free from lower extremity injury for at least 6 months prior to testing and to have no history of hip, knee, or ankle surgery.17 A complete life-screening was not performed, but the children did not report any injury (at least in the 6 months prior to testing) that could affect dynamic balance and thus the performance of the test. The children were required to be in primary school (their ages ranged from 10 to 12 years) and to be physically active, because they were required to be participating in some organized sport before the study started.
All the children and their parents signed an institutional informed consent form before starting the protocol, and the study was approved by the institutional review board at the authors’ institutions. All procedures described in this section comply with the requirements listed in the 1975 Declaration of Helsinki and its 2008 amendment.
Protocol
Height and body mass index were measured according to the protocol used in a previous studies.23 Participants were tested twice, 2 weeks apart, and measurements were performed at the same time of the day by the same single rater, according to the protocol established in a previous reliability study.13 The rater was a researcher with some experience in performing SEBT studies at a university. To avoid possible distractions that could influence the results, the children were individually tested in the sports facility while the other subjects waited outside. The SEBT was performed with both limbs, following the recommendations by Gribble et al,10 and was performed in 3 directions (anterior, posteromedial, and posterolateral, in this order). This modification reduces the time necessary to perform the SEBT10 and thus is a more practical way to use the test in a school setting. Four practice trials were performed in each direction before selecting 3 additional distances reached in order to minimize practice effects.17,24 The best value of the 3 measured trials was selected, as in previous studies.11,17 The subjects performed all the reaching distances with 1 leg and then with the contralateral leg in a counterbalanced order. After finishing the practice trials, the subjects had 30 seconds to rest before performing the next 3 trials. The subjects performed the test barefoot, with the stance foot aligned at the most distal aspect of the toes for anterior direction and the most posterior aspect of the heel for the backward directions.10 During the trials, the hands were placed on the hips, and minimal stance foot movement was allowed.10 The test started from a bipedal position. Then the participants were asked to maintain a single leg stance on 1 leg while reaching as far as possible with the opposite leg to touch as far as possible along the chosen line with the most distal part of their foot.10,17 The subjects then returned to the initial stance.10,17 The point at which the subject touched the line was marked by the examiner and measured manually using a measuring tape.17 Leg length was measured, quantifying the distance from the anterosuperior iliac spine to the center of the ipsilateral medial malleolus with the participant lying supine.25 This
© The Physician and Sportsmedicine, Volume 42, Issue 4, November 2014, ISSN – 0091-3847 121 ResearchSHARE®: www.research-share.com • Permissions: [email protected] • Reprints: [email protected] Warning: No duplication rights exist for this journal. Only JTE Multimedia, LLC holds rights to this publication. Please contact the publisher directly with any queries.
Calatayud et al
measure was used to normalize the distances reached, dividing the distance reached by leg length and then multiplying by 100.25 A trial was discarded and repeated if participants used the reaching leg for a substantial amount of support at any time, removed the foot from the center of the grid, were unable to maintain balance,25 lifted their heel off the ground, lifted their hands off the hips, or did not follow the previously mentioned instructions in performing the test.
Table 1. Mean, SD, and P Values for Normalized Maximum Excursion Distancesa Anterior Posteromedial Posterolateral
Left stance Right stance Left stance Right stance Left stance Right stance
Test
Retest
P value
67.43 (8.75) 69.17 (8.96) 84.80 (11.89) 84.51 (14.32) 75.83 (12.43) 74.78 (13.93)
65.88 (15.27) 70.23 (8.14) 82.54 (22.40) 86.11 (15.33) 75.89 (11.82) 76.33 (16.23)
0.536 0.249 0.541 0.178 0.957 0.219
Values are mean ± SD for normalized maximum excursion distance. P values are for the paired t test on test–retest differences.
a
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Data Analysis
Statistical analysis was carried out using SPSS version 17 (SPSS Inc., Chicago, IL). The level of significance was set at P , 0.05 for all statistical tests. Means and standard deviations were calculated for the maximum distance reached in each direction for both limbs. Paired t tests of the differences of scores obtained at test and retest sessions were used to ensure the absence of any systematic bias.26 The ICC (3,1) was calculated for each reaching direction to assess the relative between-session reliability, normalizing the measurement error relative to the heterogeneity of the subjects.14 The SEM (pooled standard deviation of all scores multiplied by the square root of 1 – ICC)14 and the 95% CIs were computed to estimate the amount of error associated with the measurement. In addition, the minimum difference (MD) was calculated (SEM * 1.96 * √2) to determine the minimum threshold of measurement to ensure that differences between measurements were real and outside the error range.14 Criteria ranges for ICC reliability were as follows: , 0.50, poor; 0.50 to 0.75, moderate; and . 0.75, good.27
Results
Paired t tests revealed no significant differences between the scores of the 2 testing sessions for all directions reached in both limbs (P . 0.05). Mean, standard deviation, and P values of the paired t test for normalized maximum distances reached in both limbs are reported in Table 1. The ICC values for normalized scores showed moderate to good reliability (0.51 to 0.93), and the SEM values for normalized scores ranged from 3.03 to 12.32. Table 2 shows the mean, standard deviation, 95% CI, SEM, MD, and ICC values for normalized reaching distances.
Discussion
In accordance with the hypothesis, SEBT showed moderate to high reliability scores (0.51 to 0.93) in primary school 122
children. Similar intratester ICC results have been reported previously in healthy young adults, where SEBT ICCs ranged from 0.84 to 0.92,17 0.67 to 0.87,2 0.78 to 0.96,16 and 0.82 to 0.87.11 In addition, intertester ICCs have ranged from 0.35 to 0.9316 and from 0.86 to 0.92.18 Although the ICC provides a relative measure of reliability, the SEM provides an absolute reliability index14 and quantifies the scores’ precision.28 Relative reliability addresses the consistency of the position or the rank of the subjects in the group relative to others, whereas absolute reliability addresses the consistency of the subjects’ scores.14 In our study, the SEM values for normalized scores ranged from 3.03 to 12.32. Concretely, the lowest SEM result was found in the anterior reach direction with the right stance, also showing the lowest minimal distance value (8.39). Previous SEM values ranged from 1.77 to 3.38,16 3.43 to 4.78,2 and 1.95 to 2.54,17 whereas the only study reporting MD data during the SEBT performance showed values ranging from 6.13 to 8.15.17 A possible explanation for the highest SEM value in our study (12.32) and the lowest ICC value (0.51) across all the SEBT reliability studies is that primary school children might need a greater number of demonstrations and practice trials in order to improve their technique. However, this value pertains to a specific reach (posteromedial direction with left stance), and the other results in our study are in accordance with the range of values previously reported. It should be pointed out that the different results from different studies could be due to the different testing procedures performed. For example, our study was the first that conducted a 2-session model with 2 weeks between tests, whereas the subjects in the other studies has at most 1 week between tests.17 In addition, some SEBT reliability studies performed the 8 reaching directions,2,16,17 whereas other studies performed only 3 reaching directions.18 Differences in the number of trials, the familiarization sessions, and other aspects of the performance (eg, hands placed on hips,
© The Physician and Sportsmedicine, Volume 42, Issue 4, November 2014, ISSN – 0091-3847 ResearchSHARE®: www.research-share.com • Permissions: [email protected] • Reprints: [email protected] Warning: No duplication rights exist for this journal. Only JTE Multimedia, LLC holds rights to this publication. Please contact the publisher directly with any queries.
SEBT Reliability in Primary School Children
Table 2. Mean, SD, 95% CI, SEM, MD, and ICC Values for Normalized Excursion Distances Anterior Posteromedial Posterolateral
Left stance Right stance Left stance Right stance Left stance Right stance
Mean
SD
95% CI
66.65 69.69 83.67 85.31 75.86 75.55
12.20 8.39 17.60 14.53 11.87 14.83
63.11 66.78 78.39 81.32 73.58 71.47
73.29 70.48 93.48 86.09 78.02 76.53
SEM
MD
ICC
8.36 3.03 12.32 3.85 3.56 4.20
23.19 8.39 34.15 10.66 9.88 11.63
0.53 0.87 0.51 0.93 0.91 0.92
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Abbreviations: ICC, intraclass correlation coefficient; MD, minimal difference; SEM, standard error of measurement.
barefoot or not, and foot alignment) also could influence the results and thus the reliability of the studies. We are confident that additional familiarization sessions and additional practice trials might have helped to improve the reliability in our study, and thus these factors are the main limitations. However, the number of trials performed was enough to minimize practice effects in previous reliability studies.17,24 Furthermore, a mean score of the 3 measured trials could provide higher reliability values as has been recently demonstrated.18 Because we recorded only the best value, future studies should include this variation to improve the reliability of the test in this population. Field-based tests in the school setting must be timeefficient and inexpensive, must require only minimal equipment, and must be easily administered to a large number of children simultaneously.29 For example, it took 3 physical education sessions of approximately 55 minutes each for a single tester to administer a validated battery of 6 fitness tests to 20 children.29 However, 6 physical education sessions were needed in our study to perform all the measurements. The time required to perform the practice trials and ensure the correct performance of the test may be excessive if the purpose is to measure a large number of participants in a single physical education session. Thus, the time needed to perform the SEBT is a limitation in some settings. Another limitation is that $ 2 examiners may be required to observe and ensure an adequate testing technique and to mark the distances reached. The performance of the SEBT in the school setting may have additional limitations. In our study, the children were tested individually to avoid the distraction of having their peers present. Moreover, the number of subjects involved and time constraints may represent further limitations to performing the SEBT during the physical education classes. Because this is the first SEBT reliability investigation that was conducted in the school setting, our results provide a first step for future studies that can attempt to find optimal methods and procedures to provide more reliable results.
Conclusions
The moderate to good absolute and relative reliability values show that the SEBT is a repeatable measure for primary school students in different testing sessions. Thus, the SEBT may be used to assess dynamic balance in children. However, the difficulty and time needed for a single examiner to conduct the testing might prove impractical in the school setting. The SEBT might be more appropriate in extracurricular sports where there are fewer time constraints.
Acknowledgments
The authors thank the children who participated in this study as well as their teachers at the Padre Moreno School for their cooperation. In addition, we thank Craig Denegar and Germán Martín for their assistance.
Conflict of Interest Statement
Joaquin Calatayud, MSc, Sebastien Borreani, PhD, Juan Carlos Colado, PhD, Fernando Martin, PhD, and Jorge Flandez, PhD, have no conflicts of interest to declare.
References 1. Gallahue DL. Understanding Motor Development: Infants, Children, Adolescents, Adults. New York: McGraw-Hill; 2011. 2. Kinzey SJ, Armstrong CW. The reliability of the Star-Excursion test in assessing dynamic balance. J Orthop Sports Phys Ther. 1998;27(5):356–360. 3. Miller MG, Herniman JJ, Ricard MD, Cheatham CC, Michael TJ. The effects of a 6-week plyometric training program on agility. J Sport Sci Med. 2006;5(3):459–465. 4. Fong DT, Hong Y, Chan LK, Yung PS, Chan KM. A systematic review on ankle injury and ankle sprain in sports. Sports Med. 2007;37(1):73–94. 5. Witchalls J, Blanch P, Waddington G, Adams R. Intrinsic functional deficits associated with increased risk of ankle injuries: a systematic review with meta-analysis. Br J Sports Med. 2012;46(7):515–523. 6. Granacher U, Gollhofer A. Is there an association between variables of postural control and strength in prepubertal children? J Strength Cond Res. 2012;26(1):210–216. 7. España-Romero V, Artero EG, Jimenez-Pavón D, et al. Assessing healthrelated fitness tests in the school setting: reliability, feasibility and safety; the ALPHA Study. Int J Sports Med. 2010;31(7):490–497. 8. Williams HG, Pfeiffer KA, O’Neill JR, et al. Motor skill performance and physical activity in preschool children. Obesity. 2008;16(6):1421–1426.
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Calatayud et al 9. Schneider S, Yamamoto S, Weidmann C, Brühmann B. Sports injuries among adolescents: incidence, causes and consequences. J Paediatr Child Health. 2012;48(10):E183–E189. 10. Gribble PA, Hertel J, Plisky P. Using the Star Excursion Balance Test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review. J Athl Training. 2012;47(3):339–357. 11. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star excursion balance test as a predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther. 2006;36(12):911–919. 12. Currell K, Jeukendrup AE. Validity, reliability and sensitivity of measures of sporting performance. Sports Med. 2008;38(4);297–316. 13. Ortega FB, Artero EG, Ruiz JR, et al. Reliability of health-related physical fitness tests in European adolescents. The HELENA Study. Int J Obesity. 2008;32(5):49–57. 14. Weir JP. Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM. J Strength Cond Res. 2005;19(1):231–240. 15. Hopkins WG. Measures of reliability in sports medicine and science. Sports Med. 2000;30(1):1–15. 16. Hertel J, Miller SJ, Denegar CR. Intratester and intertester reliability during the star excursion balance tests. J Sport Rehabil. 2000;9: 104–116. 17. Munro AG, Herrington LC. Between-session reliability of the star excursion balance test. Phys Ther Sport. 2010;11(4):128–132. 18. Gribble PA, Kelly SE, Refshauge KM, Hiller CE. Interrater reliability of the star excursion balance test. J Athl Train. 2013;48(5):621–626. 19. Gorman PP, Butler RJ, Rauh MJ, Kiesel K, Plisky PJ. Differences in dynamic balance scores in one sport versus multiple sport high school athletes. Int J Sports Phys Ther. 2012;7(2):148–153.
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20. Sandrey MA, Mitzel JG. Improvement in dynamic balance and core endurance after a 6-week core-stability-training program in high school track and field athletes. J Sport Rehabil. 2013;22(4):264–271. 21. Houghton KM, Guzman J. Evaluation of static and dynamic postural balance in children with juvenile idiopathic arthritis. Pediatr Phys Ther. 2013;25(2):150–157. 22. Ruiz JR, Castro-Piñero J, Artero EG, et al. Predictive validity of health-related fitness in youth: a systematic review. Br J Sports Med. 2009;43(12):909–923. 23. García-Massó X, Colado JC, González LM, et al. Myoelectric activation and kinetics of different plyometric push-up exercises. J Strength Cond Res. 2011;25(7):2040–2047. 24. Robinson RH, Gribble PA. Support for a reduction in the number of trials needed for the Star Excursion Balance Test. Arch Phys Med Rehab. 2008;89(2):364–370. 25. Gribble PA, Hertel J. Considerations for normalising measures of the star excursion balance test. Meas Phys Educ Exerc Sci. 2003;7(2):89–100. 26. Atkinson G, Nevill AM. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Med. 1998;26(4):217–238. 27. Portney LG, Watkins MP. Foundations of Clinical Research: Applications to practice. Upper Saddle River, NJ: Prentice Hall Health; 1999. 28. Harvill LM. Standard error of measurement. Educ Meas. 1991; 10(2):33–41. 29. Ruiz JR, Castro-Piñero J, España-Romero V, et al. Field-based fitness assessment in young people: the ALPHA health-related fitness test battery for children and adolescents. Br J Sports Med. 2011;45(6):518–524.
© The Physician and Sportsmedicine, Volume 42, Issue 4, November 2014, ISSN – 0091-3847 ResearchSHARE®: www.research-share.com • Permissions: [email protected] • Reprints: [email protected] Warning: No duplication rights exist for this journal. Only JTE Multimedia, LLC holds rights to this publication. Please contact the publisher directly with any queries.
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Test-Retest Reliability of the Star Excursion Balance Test in Primary School Children
DOI: 10.3810/psm.2014.11.2098
Joaquin Calatayud, MSc 1 Sebastien Borreani, PhD 1 Juan Carlos Colado, PhD 1 Fernando Martin, PhD 1 Jorge Flandez, PhD 2 1 Research Group in Sport and Health, Laboratory of Physical Activity and Health, Department of Physical Education and Sports, University of Valencia, Valencia, Spain; 2 Austral University of Chile, Faculty of Pedagogy in Physical Education, Sports, and Recreation, Valdivia, Chile
Abstract
Background: Dynamic balance has been considered a fundamental skill at all ages and is required for normal daily tasks, such as walking, running, or other sports activities. The Star Excursion Balance Test (SEBT) has been widely used in recent years to identify dynamic balance deficits and improvements and to predict the risk of lower extremity injury. However, no study has demonstrated the reliability of the SEBT in children while they are performing the test in a physical education session. Reliability is needed in all measurement tools in order to provide repeatable and consistent data. Objective: To evaluate the reliability of the SEBT in primary school students in the school setting. Methods: Twenty-four healthy children with typical development were tested twice, 2 weeks apart. The tests were conducted by the same single rater and were performed during the physical education class. The test was performed under standardized conditions during the 2 testing sessions and was performed by each subject with both limbs in the 3 directions (anterior, posteromedial, and posterolateral). Four practice trials were performed in each direction before selecting 3 additional distances reached. The best value of these 3 additional measured trials was selected. The paired t test was used to ensure the absence of any systematic bias. Intraclass correlation coefficient, standard error of measurement, 95% confidence intervals (CIs), and minimal change values were calculated to assess reliability and measurement error. Results: The paired t tests revealed no significant differences between test–rest scores. Test–retest reliability for all distances reached was moderate to good. Conclusions: Reliability values suggest that the SEBT is suitable for primary school students. However, it may be more practical and feasible during extracurricular sports participation due to the time constraints and difficulties in using the test in the school setting. Keywords: injury risk; school setting; reliability; dynamic balance
Introduction
Correspondence: Juan Carlos Colado, PhD, Universidad de Valencia (FCAFE), Aulario Multiusos, C/ Gasco Oliag, 3, 46010 Valencia, Spain. Tel: 00-34-963-983-470 Fax: 00-34-963-864-353 E-mail: [email protected]
120
Dynamic balance has been considered a fundamental skill at all ages1 and is required for normal daily tasks, such as walking, running, or other sports activities,1,2 especially those activities that require dynamic movements while maintaining control.3 Since sports participation is one of the most frequent causes of injuries,4 and because balance is a predictor of an increased risk to sustain a lower extremity injury such as ankle sprains,5 a test that provides dynamic conditions is required in order to identify balance deficits and to assess fall risk and sports-related injury risk.6 The physical education classes may play an important role in identifying children with poor fitness7 and those at high risk of injuries. Because of their undeveloped neuromuscular system,8 children’s injury rates related to falls and sports participation are elevated.9
© The Physician and Sportsmedicine, Volume 42, Issue 4, November 2014, ISSN – 0091-3847 ResearchSHARE®: www.research-share.com • Permissions: [email protected] • Reprints: [email protected] Warning: No duplication rights exist for this journal. Only JTE Multimedia, LLC holds rights to this publication. Please contact the publisher directly with any queries.
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SEBT Reliability in Primary School Children
The Star Excursion Balance Test (SEBT) has been widely used in recent years in both healthy and injured populations to identify dynamic balance deficits and improvements and to predict the risk of lower extremity injury.10 Performing the test requires strength, flexibility, and coordination11 to maintain a single leg stance on one leg while reaching as far as possible with the contralateral leg.2 Reliability is needed in all measurement tools12 to provide repeatable13,14 and consistent15,16 data. Therefore, a reliable test is a precise measure14 that ensures similar results under the same test conditions.15 Despite the fact that the intraclass correlation coefficient (ICC) and standard error of measurement (SEM) values have shown moderate2 to high16–18 reliability for the SEBT in young adults and middle-aged adults, no study has demonstrated the between-session reliability of the SEBT in children who are performing the test in a physical education class. To our knowledge, only 2 recent investigations19,20 have tested the SEBT in schoolchildren, although these were not conducted in order to evaluate the reliability of the test. Furthermore, the use of dynamic balance tests in children is limited to costly systems such as balance platforms6 or the Biodex Balance System.21 Hence, a reliable cost-effective test that could be performed anywhere is needed to obtain dynamic balance measures and to provide useful information to identify those with greater injury risk. Moreover, it has been established that motor fitness, which includes balance and coordination, is a physical health-related component in childhood and adolescence.22 Thus, this study evaluated the relative and absolute test–retest reliability of the SEBT in primary school students in the school setting. We hypothesized that the SEBT would be a reliable measure to assess dynamic balance in this population.
Materials and Methods Participants
Twenty-four children (12 girls and 12 boys; age 11.0 ± 0.8 years, height 152.4 ± 8.7 cm, weight 45.4 ± 8.1 kg, body mass index 19.46 ± 2.63) volunteered to take part in this study. They were required to be free from lower extremity injury for at least 6 months prior to testing and to have no history of hip, knee, or ankle surgery.17 A complete life-screening was not performed, but the children did not report any injury (at least in the 6 months prior to testing) that could affect dynamic balance and thus the performance of the test. The children were required to be in primary school (their ages ranged from 10 to 12 years) and to be physically active, because they were required to be participating in some organized sport before the study started.
All the children and their parents signed an institutional informed consent form before starting the protocol, and the study was approved by the institutional review board at the authors’ institutions. All procedures described in this section comply with the requirements listed in the 1975 Declaration of Helsinki and its 2008 amendment.
Protocol
Height and body mass index were measured according to the protocol used in a previous studies.23 Participants were tested twice, 2 weeks apart, and measurements were performed at the same time of the day by the same single rater, according to the protocol established in a previous reliability study.13 The rater was a researcher with some experience in performing SEBT studies at a university. To avoid possible distractions that could influence the results, the children were individually tested in the sports facility while the other subjects waited outside. The SEBT was performed with both limbs, following the recommendations by Gribble et al,10 and was performed in 3 directions (anterior, posteromedial, and posterolateral, in this order). This modification reduces the time necessary to perform the SEBT10 and thus is a more practical way to use the test in a school setting. Four practice trials were performed in each direction before selecting 3 additional distances reached in order to minimize practice effects.17,24 The best value of the 3 measured trials was selected, as in previous studies.11,17 The subjects performed all the reaching distances with 1 leg and then with the contralateral leg in a counterbalanced order. After finishing the practice trials, the subjects had 30 seconds to rest before performing the next 3 trials. The subjects performed the test barefoot, with the stance foot aligned at the most distal aspect of the toes for anterior direction and the most posterior aspect of the heel for the backward directions.10 During the trials, the hands were placed on the hips, and minimal stance foot movement was allowed.10 The test started from a bipedal position. Then the participants were asked to maintain a single leg stance on 1 leg while reaching as far as possible with the opposite leg to touch as far as possible along the chosen line with the most distal part of their foot.10,17 The subjects then returned to the initial stance.10,17 The point at which the subject touched the line was marked by the examiner and measured manually using a measuring tape.17 Leg length was measured, quantifying the distance from the anterosuperior iliac spine to the center of the ipsilateral medial malleolus with the participant lying supine.25 This
© The Physician and Sportsmedicine, Volume 42, Issue 4, November 2014, ISSN – 0091-3847 121 ResearchSHARE®: www.research-share.com • Permissions: [email protected] • Reprints: [email protected] Warning: No duplication rights exist for this journal. Only JTE Multimedia, LLC holds rights to this publication. Please contact the publisher directly with any queries.
Calatayud et al
measure was used to normalize the distances reached, dividing the distance reached by leg length and then multiplying by 100.25 A trial was discarded and repeated if participants used the reaching leg for a substantial amount of support at any time, removed the foot from the center of the grid, were unable to maintain balance,25 lifted their heel off the ground, lifted their hands off the hips, or did not follow the previously mentioned instructions in performing the test.
Table 1. Mean, SD, and P Values for Normalized Maximum Excursion Distancesa Anterior Posteromedial Posterolateral
Left stance Right stance Left stance Right stance Left stance Right stance
Test
Retest
P value
67.43 (8.75) 69.17 (8.96) 84.80 (11.89) 84.51 (14.32) 75.83 (12.43) 74.78 (13.93)
65.88 (15.27) 70.23 (8.14) 82.54 (22.40) 86.11 (15.33) 75.89 (11.82) 76.33 (16.23)
0.536 0.249 0.541 0.178 0.957 0.219
Values are mean ± SD for normalized maximum excursion distance. P values are for the paired t test on test–retest differences.
a
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Data Analysis
Statistical analysis was carried out using SPSS version 17 (SPSS Inc., Chicago, IL). The level of significance was set at P , 0.05 for all statistical tests. Means and standard deviations were calculated for the maximum distance reached in each direction for both limbs. Paired t tests of the differences of scores obtained at test and retest sessions were used to ensure the absence of any systematic bias.26 The ICC (3,1) was calculated for each reaching direction to assess the relative between-session reliability, normalizing the measurement error relative to the heterogeneity of the subjects.14 The SEM (pooled standard deviation of all scores multiplied by the square root of 1 – ICC)14 and the 95% CIs were computed to estimate the amount of error associated with the measurement. In addition, the minimum difference (MD) was calculated (SEM * 1.96 * √2) to determine the minimum threshold of measurement to ensure that differences between measurements were real and outside the error range.14 Criteria ranges for ICC reliability were as follows: , 0.50, poor; 0.50 to 0.75, moderate; and . 0.75, good.27
Results
Paired t tests revealed no significant differences between the scores of the 2 testing sessions for all directions reached in both limbs (P . 0.05). Mean, standard deviation, and P values of the paired t test for normalized maximum distances reached in both limbs are reported in Table 1. The ICC values for normalized scores showed moderate to good reliability (0.51 to 0.93), and the SEM values for normalized scores ranged from 3.03 to 12.32. Table 2 shows the mean, standard deviation, 95% CI, SEM, MD, and ICC values for normalized reaching distances.
Discussion
In accordance with the hypothesis, SEBT showed moderate to high reliability scores (0.51 to 0.93) in primary school 122
children. Similar intratester ICC results have been reported previously in healthy young adults, where SEBT ICCs ranged from 0.84 to 0.92,17 0.67 to 0.87,2 0.78 to 0.96,16 and 0.82 to 0.87.11 In addition, intertester ICCs have ranged from 0.35 to 0.9316 and from 0.86 to 0.92.18 Although the ICC provides a relative measure of reliability, the SEM provides an absolute reliability index14 and quantifies the scores’ precision.28 Relative reliability addresses the consistency of the position or the rank of the subjects in the group relative to others, whereas absolute reliability addresses the consistency of the subjects’ scores.14 In our study, the SEM values for normalized scores ranged from 3.03 to 12.32. Concretely, the lowest SEM result was found in the anterior reach direction with the right stance, also showing the lowest minimal distance value (8.39). Previous SEM values ranged from 1.77 to 3.38,16 3.43 to 4.78,2 and 1.95 to 2.54,17 whereas the only study reporting MD data during the SEBT performance showed values ranging from 6.13 to 8.15.17 A possible explanation for the highest SEM value in our study (12.32) and the lowest ICC value (0.51) across all the SEBT reliability studies is that primary school children might need a greater number of demonstrations and practice trials in order to improve their technique. However, this value pertains to a specific reach (posteromedial direction with left stance), and the other results in our study are in accordance with the range of values previously reported. It should be pointed out that the different results from different studies could be due to the different testing procedures performed. For example, our study was the first that conducted a 2-session model with 2 weeks between tests, whereas the subjects in the other studies has at most 1 week between tests.17 In addition, some SEBT reliability studies performed the 8 reaching directions,2,16,17 whereas other studies performed only 3 reaching directions.18 Differences in the number of trials, the familiarization sessions, and other aspects of the performance (eg, hands placed on hips,
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SEBT Reliability in Primary School Children
Table 2. Mean, SD, 95% CI, SEM, MD, and ICC Values for Normalized Excursion Distances Anterior Posteromedial Posterolateral
Left stance Right stance Left stance Right stance Left stance Right stance
Mean
SD
95% CI
66.65 69.69 83.67 85.31 75.86 75.55
12.20 8.39 17.60 14.53 11.87 14.83
63.11 66.78 78.39 81.32 73.58 71.47
73.29 70.48 93.48 86.09 78.02 76.53
SEM
MD
ICC
8.36 3.03 12.32 3.85 3.56 4.20
23.19 8.39 34.15 10.66 9.88 11.63
0.53 0.87 0.51 0.93 0.91 0.92
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Abbreviations: ICC, intraclass correlation coefficient; MD, minimal difference; SEM, standard error of measurement.
barefoot or not, and foot alignment) also could influence the results and thus the reliability of the studies. We are confident that additional familiarization sessions and additional practice trials might have helped to improve the reliability in our study, and thus these factors are the main limitations. However, the number of trials performed was enough to minimize practice effects in previous reliability studies.17,24 Furthermore, a mean score of the 3 measured trials could provide higher reliability values as has been recently demonstrated.18 Because we recorded only the best value, future studies should include this variation to improve the reliability of the test in this population. Field-based tests in the school setting must be timeefficient and inexpensive, must require only minimal equipment, and must be easily administered to a large number of children simultaneously.29 For example, it took 3 physical education sessions of approximately 55 minutes each for a single tester to administer a validated battery of 6 fitness tests to 20 children.29 However, 6 physical education sessions were needed in our study to perform all the measurements. The time required to perform the practice trials and ensure the correct performance of the test may be excessive if the purpose is to measure a large number of participants in a single physical education session. Thus, the time needed to perform the SEBT is a limitation in some settings. Another limitation is that $ 2 examiners may be required to observe and ensure an adequate testing technique and to mark the distances reached. The performance of the SEBT in the school setting may have additional limitations. In our study, the children were tested individually to avoid the distraction of having their peers present. Moreover, the number of subjects involved and time constraints may represent further limitations to performing the SEBT during the physical education classes. Because this is the first SEBT reliability investigation that was conducted in the school setting, our results provide a first step for future studies that can attempt to find optimal methods and procedures to provide more reliable results.
Conclusions
The moderate to good absolute and relative reliability values show that the SEBT is a repeatable measure for primary school students in different testing sessions. Thus, the SEBT may be used to assess dynamic balance in children. However, the difficulty and time needed for a single examiner to conduct the testing might prove impractical in the school setting. The SEBT might be more appropriate in extracurricular sports where there are fewer time constraints.
Acknowledgments
The authors thank the children who participated in this study as well as their teachers at the Padre Moreno School for their cooperation. In addition, we thank Craig Denegar and Germán Martín for their assistance.
Conflict of Interest Statement
Joaquin Calatayud, MSc, Sebastien Borreani, PhD, Juan Carlos Colado, PhD, Fernando Martin, PhD, and Jorge Flandez, PhD, have no conflicts of interest to declare.
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