Currently, there is an emerging necessity to assess health-related fitness at an early age (19). In this regard, the importance of including cardiorespiratory fitness tests in monitoring systems from early ages has been highlighted (7), as it is considered as an important marker for health and disease during childhood (2,22). Consequently, there is a parallel need to use reliable measures to assess cardiovascular fitness in young children (22). Scientific research has shown that the cardiorespiratory fitness level of preschoolers can be objectively measured through laboratory tests based on direct measures of this physiological variable (8,16). However, these tests are expensive and require highly trained experimenters; thus, they are not feasible for their use in preschool and kindergarten settings. On the contrary, field-based fitness tests are easy to administer and involve minimal equipment, minimal cost, and a larger number of participants can be evaluated in a relatively short period (9). Therefore, in the preschool setting, cardiorespiratory fitness field-based tests are a practical and feasible option. Nevertheless, there is scant information regarding the reliability of field-based cardiovascular fitness tests that can be administered with children aged 4 and 5. This lack of information seems to be a gap in pediatric research that needs to be filled.
When assessing cardiorespiratory fitness in children, there are 2 field-based tests that are widely used: Course-Navette (15) and Mini-Cooper (5). Course-Navette is a popular choice because the beginning stages are not overly intense, the pacing is external and therefore controlled, and the work loading patterns are similar to those of graded exercise testing. Mini-Cooper is an alternative and interesting option because it is a short test that allows children to keep running at the same pace and stay motivated during the test performance. Course-Navette test was found to be reliable in children aged 6–16 years (15), whereas Mini-Cooper test was found to be reliable in children aged 9–11 years (17). Although it has been demonstrated that it is reliable to evaluate cardiovascular fitness by means of field-based test in preschool children (28), and despite the fact that both tests have been used for preschool research (11–13,21), little is known about their reliability when administered in this population. This is important because only when test scores are valid can they be used as the basis for evaluation, and therefore, a test cannot be valid unless it is reliable. Under these circumstances, this study is aimed at establishing reliability evidence for Course-Navette and Mini-Cooper tests in a sample composed of children older than 3 and younger than 6 years old. Based on the past research, it has been hypothesized that Course-Navette and the Mini-Cooper tests are accurate and reliable tools for the assessment of cardiovascular fitness of preschool children, independently of their age and sex.
Experimental Approach to the Problem
Reliability refers to the reproducibility of values of a test in repeated trials on the same individual. In this study, test-retest reliability was chosen as a method for testing the stability and reliability of cardiorespiratory fitness field-based tests over time. Test-retest reproducibility or consistency over time is a key aspect of reliability because it is critical for evaluating whether an observed change is real (14). The problem with testing reliability through the test-retest method is the length of time between test administrations. The length of time should be short enough, so that the examinees' skills in the area being assessed have not changed because of additional learning. However, a very short time interval makes the carryover effects due to memory, practice, or mood more likely. Conversely, a long time interval increases the likelihood that a change in status may occur (1). In this regard, most researchers have chosen an interval ranging from 2 days to 2 weeks. This time frame is generally believed to be a reasonable compromise between recollection bias and unwanted (on the part of the investigator) clinical change (20). In this study, it was decided to carry out the measurements using the same cardiorespiratory fitness field-based tests on 3 occasions and 7 days apart. This time interval was chosen because, on functional tests, a period of 1 week was considered sufficient to analyze their test-retest reliability without introducing additional error due to maturation (19). Performance of 3 trials was considered convenient because, when testing reliability by means of the test-retest method, it increases the potential for learning, carryover, or recall effects (i.e., the first test may influence the second) (1). Performance of 3 trials seems to be a frequent choice when analyzing field-based test reliability on preschool children (3,28).
Thus, tests were carried out in three stages. The first stage was used for the introduction and explanation of the tests with the aim of obtaining the right performance on the part of children participants and avoiding a possible learning effect. The results in each test for this first attempt were not taken into account for further analysis. The second stage was used as a test phase and the third stage as a retest phase. Comparing the scores of the second and third stages for each performance allowed us to analyze the reliability of cardiorespiratory fitness field-based tests.
In this study, the age and sex of the sample have been considered as independent variables, whereas the cardiorespiratory fitness level is recognized as the dependent variable assessed through Course-Navette, Mini-Cooper, and 3-minute shuttle run tests. The study of the reliability of health-related fitness tests can be affected by systematic bias (i.e., participants who show boredom or lack of motivation when performing the same test on several occasions) and random change (random error of measurement, which is greater in smaller samples) (19). According to this, it was decided that the participants should carry out a third cardiorespiratory fitness field-based test whose reliability was established beforehand. In this regard, the 3-minute shuttle run test has shown an acceptable reliability level when assessing cardiorespiratory fitness in kindergarten children (24). Therefore, as a way of reinforcing the reliability study of Course-Navette and Mini-Cooper when administering them to young children, the degree of association of both tests with the 3-minute shuttle run was taken into account.
Calculation of the potential sample for the reliability study resulted in a sample size of 97 individuals, established through a reliability level (confidence interval [CI]) of 95% (1 − α), an accuracy of 96% (d), and having considered a 4% of the proportion. We have taken into account an expected 5% loss in the calculation.
The participants were 97 healthy Spanish urban children between 4 and 5 years old recruited from a kindergarten located in the North of Spain. Those who were enrolled in the second year of the initial stage of the Spanish Education Curriculum and did not show any type of pathology that could prevent practice of aerobic physical exercise, as well as participation in evaluation tests, were deemed eligible for the study. At the end of the research, data were collected from 48 boys (mean age: 4.4 ± 0.5 years; mean body mass index [BMI]: 16.04 ± 1.52 kg·m−2) and 49 girls (mean age: 4.3 ± 0.4 years; mean BMI: 16.48 ± 1.04 kg·m−2).
Parental permission and child assent were obtained after stakeholders were informed that they could decide whether or not to take part in the study, what the objectives were, and the possible risks and benefits. The study was conducted according to the Declaration of Helsinki, and the protocol was fully approved by the local Research Ethics Committee before initiating the assessment.
Research took place during the second term of the academic year 2013 or 2014, and all tests were carried out during the 2 weekly sessions of psychomotricity in which children were participating as part of the preschool academic curriculum in Spain. Such sessions, which were aimed at the development of basic motor skills (balancing, throwing, jumping, etc.), took place three hours after the children started their school day and were carried out with a 3-day interval between them. Participants were not allowed to drink or eat two hours before the assessment sessions, which were performed in groups of 10 children in 6-week blocks. One kindergarten teacher and 1 preschool teacher controlled and supervised the assessment sessions. Two senior students of the Degree in Early Childhood Education were put in charge of test administration. Their speciality was Physical Education; therefore, they were familiar with test protocols.
To measure the weight and height of the participants, a digital scale (Tefal PP1200VO, Barcelona, Spain) and a portable statimeter (Seca 225, Hamburg, Germany) were used. Body mass index was calculated dividing the body weight in kilograms by the height in meters squared (kg·m−2). Measurements took place during the first assessment session of the first week. For this, children were asked to wear light clothing and remove their shoes.
Throughout the first and the second sessions of the first week, children were told how to perform both the Mini-Cooper and the 3-minute shuttle run tests. In the first session of the second week, the Course-Navette test was explained and carried out, and during the second session, typical psychomotricity activities were developed. This first stage was considered as a familiarization phase, which helped to avoid the learning effect in subsequent assessments. In the first session of the third week, the pupil did the Mini-Cooper test and, in the second session, the 3-minute shuttle run test. During the first session of the fourth week, the Course-Navette test was performed. The second research stage was regarded as the test phase. The fifth and sixth weeks followed the same structure as the third and fourth, which involved Mini-Cooper, 3-minute shuttle run, and Course-Navette in the same order referred earlier. The third research stage was considered as the retest phase.
When performing Course-Navette, children were required to run and shuttle back between 2 lines placed 20 m apart, at increasing speeds. The running speed started at 8.5 km h−1 and rose gradually at the rate of 0.5 km·h−1·min−1. Each speed increase corresponded to a level change. Classes were divided into smaller groups to complete the test, and the teacher ran with the students in the first level only. The test ended either when the student was not able to reach the end of the track within the given time on 2 successive shuttles or if he or she withdrew voluntarily. Scores were recorded as the last level and shuttle students could reach in the test and then were converted to the number of seconds completed to provide a continuous variable for analysis.
In the case of Mini-Cooper, children had to move around a rectangle mark on the ground as fast as possible for a 6-minute period. Said rectangle was 18 × 9 m. Both running and walking were allowed. The test item score was the distance (in meters) covered in the 6-minute period. Again, classes were divided into smaller groups to complete the test.
For the 3-minute shuttle run test, 2 poles (1.5 m in height) were placed 10 m apart to form a straight 10-m-long running track. Children had to run from one side to the other, go around the pole, and then return to the starting point. The score was the distance (in meters) covered in 3 minutes.
A descriptive analysis (mean ± SD and median) was applied in relation to the age and sex of the participants. Student's t-test for independent data was used to verify differences between variables. Intraclass correlation coefficient (ICC) and CI were used to assess the reliability of the three tests. Pearson's correlation analysis, developed by stratifying the analysis according to the children's age, was also applied to determine the degree of correlation between Mini-Cooper, Course-Navette, and 3-minute shuttle run tests.
Statistical significance determined a priori was set at p ≤ 0.05 for all statistical tests. All statistical analyses were performed using Statistical Package for Social Sciences 19 (SPSS Inc.; Chicago, IL, USA), and a linear statistical model was considered for the analysis.
Descriptive statistics is reported in Table 1. No difference emerged in relation to sex (data not shown).
All tests showed a high reliability (8.18 < ICC > 9.46; p ≤ 0.005) as shown in Table 2.
Table 3 refers the degree of association between Mini-Cooper and Course-Navette tests with respect to the 3-minute shuttle test. Mean scores of the 3-minute shuttle run test did not show any significant correlation with the mean scores obtained in Mini-Cooper test and Course-Navette test in the case of 4-year-old children. Comparison of mean scores in the second attempt indicated that Mini-Cooper (retest) and Course-Navette (retest) showed a degree of correlation for the same age group (r = 0.358; sig = 0.004 and r = 0.397; sig = 0.001, respectively). In the case of 5-year-old children, Mini-Cooper and Course-Navette also showed correlation both in the test (r = 0.693; sig = 0.001 or r = 0.532; sig = 0.001) and in the retest (r = 0.695; sig = 0.001 or r = 0.541; sig = 0.008) phase.
The present results showed satisfactory test-retest reliability for both the Course-Navette and Mini-Cooper tests. This study corroborates previous findings (11,21) and adds further information relative to test-retest reliability. Indeed, Niederer et al. (21) found that reliability of the Course-Navette was high for children aged 4–6 years old, but they only included 20 people in their pilot study and no further data were provided. Similarly, Reeves et al. (27) analyzed reliability for the case of Progressive Aerobic Cardiovascular Endurance Run (PACER), an adapted version of Course-Navette for children aged 5 to 6. Nevertheless, the authors restricted themselves to reporting that no significant differences had been observed between PACER's test and retest. It should be kept in mind that no analysis was offered for test reliability, and no comment was made concerning the age of the 17 participants. In this line, Fjørtoft et al. (11) study the reliability of Mini-Cooper in a group of children between 5 and 12 years old. However, they only included a sample of 21 children aged 5, and no information of test reliability was provided in this specific age group. These findings are of interest for health professionals and preschool teachers. Nevertheless, although it has been suggested that this kind of tests has a fair amount of content (logical) validity because of their natural association with aerobic exercise, they may lack evidence of concurrent validity (28). Thus, the important diagnostic information that can be provided by Course-Navette and Mini-Cooper when administered to preschoolers is limited.
A standard procedure for determining the concurrent validity of a distance run test is to correlate the scores of the test with an indicator of cardiorespiratory function, such as maximal oxygen consumption. To the authors' knowledge, no study regarding the validity of a field-based test for predicting this physiological variable following such procedure with children under 6 years old has been published. This may be due to the inherent difficulties of carrying out this type of research with children of such a young age, among them, parents' reluctance to allow their children to participate in experimental settings when invasive methods are applied or some attendant risks might be present, children's motivation, and that test procedure may not reflect their naturally intermittent movement pattern. In this research, the extent to which Course-Navette and Mini-Cooper showed some degree of association with the 3-minute shuttle run test was analyzed to provide further information about their usefulness with preschool children. Although a familiarization stage has been included, lack of a significant association between successive performances of the 3-minute run test and the other 2 field tests in 4-year-old children deserves further consideration. In particular, it has been suggested that tolerance level to exercise in very young children may be the result of emotional factors rather than real fatigue (8). Therefore, we can speculate that the 3-minute test could be more feasible and attractive for little children than Course-Navette and Mini-Cooper. A possible explanation for this lack of correlation in the younger group could be due to difficulties in understanding and correctly performing both tests in their first attempts. Indeed, this population would need at least 3 familiarization sessions before their cardiorespiratory fitness is assessed by means of maximal effort tests (22). Actually, some problems may also arise when administering field tests in preschool settings. In particular, during the execution of Course-Navette, some children hardly completed 1 or 2 shuttles, perhaps because the 20-m distance is excessive for preschool children and not because their cardiorespiratory fitness is in any way limited. In this regard, it would be interesting to study the applicability of a shuttle run test over a short distance, as it has been proposed with other populations that presented limitations in the face of longer distances (10). Alternatively, the initial running speed could be lowered without affecting test reliability, as a recent study, which was published after the present research was concluded, has shown. (6).
Similarly, during Mini-Cooper, some children chose to slow down and run along with another peer, especially if they were in first place. Keeping this in mind, it could be discussed whether it is important to raise the children's awareness about the need to evaluate their maximum effort capacity by telling them that their position, relative to that of their peers, is going to be assessed (3). Nevertheless, it is necessary to remark that none of the children disengaged running or stopped prematurely during the tests, a situation that seems likely to occur when assessing cardiorespiratory fitness with this population (25).
Finally, it seems necessary to point out that average values obtained by preschoolers in this set of field-based tests might be considered as relatively low, judging by the information that is available on the topic. An instance of this would be the fact that the average distance achieved in 3-minute shuttle run tests was about 30 m below that attested in other research performed with children of the same age (4,24). This could be because of BMI differences between sample populations, given the inverse relationship of BMI with cardiorespiratory fitness level (18). In fact, if Center for Disease Control and Prevention growth charts are taken as a reference (23), children aged 4 and 5 in this study would be placed around percentiles 60 and 75 for the BMI variable. Equivalent samples in the above mentioned pieces of research, however, were around, or even below, percentile 50. Nevertheless, according to Ballabeina (21), preschoolers who underwent Course-Navette testing reached an average duration of about 3 minutes, which is almost 3 times higher than the result of this study, despite BMI being similar. These differences may be due to other directly related aspects, such as children's capacity to pace themselves, motor competence, or motivation, all of them inherent to test administration.
There are few field tests aimed at the assessment of cardiorespiratory fitness in children aged four and five. Despite this, the 3-minute shuttle run, which has been used in this study, and the run/walk tests in distances of 1 mile, 3 quarters of a mile, and half a mile have proved to be advantageous under certain conditions (28). Although Course-Navette and Mini-Cooper showed satisfactory levels of test-retest reliability, we must acknowledge limitations in their validity, a factor that has not yet been sufficiently studied. Reliability, however, is a key factor in fitness testing. Both Course-Navette and Mini-Cooper are running performance tests. Indeed, running performance is a fundamental health component (26), as it provides testers with an accurate measure of physical work capacity. Although this study has not focused on validity analysis, the use of running performance tests with preschoolers seems to be an appropriate choice.
Still, these results are to be interpreted in the light of their limitations, such as the lack of information regarding maturity levels of the sample population, and the influence the examiner may have had in test assessment and performance (interrater reliability).
In closing, the results of this study suggest that Course-Navette and Mini-Cooper are reliable measures of cardiorespiratory fitness that can be used to assess health-related fitness in preschool children. Furthermore, studies should aim at identifying the validity of both tests with this type of population.
The results of this study contribute to enhance the scientific evidence regarding reliability of common cardiorespiratory field-based tests when administered in a preschool setting. The implication for practitioners using Course-Navette and Mini-Cooper with children between the ages of 3 and 6 is that both seem to be reliable field-based tests of cardiorespiratory fitness for that particular age group. This information can be useful for health and physical education professionals because, by administering these tests, they can collect reliable longitudinal data that may provide valuable information about changes in the level of cardiorespiratory fitness of children over a period of time. These data can be used to plan prophylactic interventions in a group level or to evaluate the effects of such interventions (11). In this sense, the strength and conditioning professionals need to identify a physical fitness profile to be used as a reference when evaluating the cardiorespiratory fitness level in young children. Although the results presented here cannot be considered normative data, they can be used for such purposes. In this way, once the scores have been interpreted, they may be used to track fitness changes over time, to evaluate the effectiveness of training programs, or even to screen children in search of future talents. In addition, if results are considered reliable and valid, they could have further applications, such as the design of a health and fitness archetype for young children, which is supported by values obtained through the performance of field-based tests. In future, this could prove to be a very productive line of research.
Finally, useful advice for practitioners who decide to administer these tests can be derived from this study. For instance, it seems necessary in Course-Navette that an adult runs along with the children to provide encouragement and motivation. In the same line, running at top speed for 6 minutes might be a difficult and abstract concept for the test population, whereas inability to cope with breathlessness and fatigue and lack of knowledge about pace are other important issues to consider when conducting Mini-Cooper test. Bearing this in mind, and based on the experience of this research, it seems that the 3-minute shuttle run is the test that young children understood better and performed more efficiently.
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